Computational Fluid Dynamics (CFD)-based simulation has been the traditional way to model complex industrial systems and processes. One very large and complex industrial system that has benefited from CFD-based simulations is the steel blast furnace. The problem with the CFD-based simulation approach is that it tends to be very slow to generate data. The CFD-only approach may not be fast enough for use in real-time decision-making. To address this issue, in this work, the authors propose the use of machine learning techniques to train and test models based on data generated via CFD simulation. Regression models based on neural networks are compared to tree boosting models. In particular, several areas (tuyere, raceway, and shaft) of the blast furnace are modeled using these approaches. The results of the model training and testing are presented and discussed. The obtained R2 metrics are, in general, very high. The results look promising and may help to improve the efficiency of operator and process engineer decision-making when running a blast furnace.

Powder metallurgy is a preferred manufacturing method in various industries because it offers design flexibility, material efficiency and a cost-effective production. In this work, we study the effects of different compaction directions on the strength of parts produced by powder metallurgy. Al–4wt.%Cu alloys are used due to their recyclability, and three distinctive compaction pressures are applied, resulting in two sample groups. One group is air-cooled after sintering, while the other is water-quenched and naturally aged (T4 temper). Both the compressive and tensile strengths are measured and analyzed. The study reveals that both heat treatments and compaction directions significantly influence anisotropic strengths. The novelty of this research lies in the use of powders that can be reused from machining, turning, or foundry rejection. By omitting or reducing the melting stage and employing simple powder metallurgy, the cost-effective and environmentally friendly processes are achieved. The planning of compaction load, compaction direction, and heat treatments is found to play a crucial role in determining the final mechanical performance. Notably, this approach aligns with the environmental, social and governance (ESG) practices that have been increasingly adopted by industry.

Transmission electron microscopy methods were used to analyze the cementite substructure in the head of special-purpose long rails of DT400IK category made of hypereutectoid steel after long-term operation on an experimental track on the Russian Railways ring (the passed tonnage is 187 million tonnes). It is noted that the study of various aspects of cementite – its structure, morphology, chemical composition, crystal lattice defects is relevant. The steel structure is represented by three morphological components at a distance of 10 mm from the sample surface: lamellar perlite, fractured and fragmented perlite. The volume fraction of lamellar perlite in the material is 65%. It is shown that after operation, the cementite plates are bent and separated by ferrite bridges. In the plates of ferrite and cementite, a dislocation substructure is formed which is of chaotically distributed and network type in ferrite and of ordered type in cementite. An increased density of dislocations at ferrite-cementite interfaces compared to the volume of ferrite plates was noted. Two possible mechanisms of deformation transformation of lamellar perlite grains are indicated: fracture of cementite plates and carbon pulling out from the lattice of the carbide phase. It is indicated that in the dissolution of cementite plates, the interfacial boundaries “α-phase-cementite” play an important role. The removal of carbon from cementite plates occurs most intensively near defects in ferrite and cementite. The formed nanosized particles of tertiary cementite are unevenly distributed in the ferrite plates, most of them are observed at the locations of ferrite subgrains and interfacial boundaries. This results in non-uniform diffraction contrast in dark-field images of cementite plates. Nanosized particles of cementite can be taken out into the interlamellar space of pearlite colonies in the process of dislocation slip, or they are formed as a result of deformation decomposition, which is less likely. Fragmentation of ferrite and cementite plates is revealed and azimuthal components of total misorientation angles are estimated. The mechanisms of mass transfer of carbon atoms over interstitial sites, deformation vacancies, dislocation tubes, grain boundaries and fragments are considered. According to all the established patterns of the cementite substructure transformation, a comparison with the results for rails made of hypoeutectoid steel was performed.

This work aims to explore the impact of side loads, drill-pipe tool-joint (DP-TJ) speed (RPM), and mud type on the austenitic stainless steel SM2535-110 casing wear characteristics. Actual field drill pipe tool joints, casings, and drilling muds are used in this study. The results of the study show that under both types of lubrication, the wear volume increased with radial load and DP-TJ speed. SM2535-110 casing specimens tested under oil-based mud (OBM) lubrication had higher casing wear volumes than those obtained under water-based mud (WBM) lubrication. This unexpected behavior is mainly due to the increase in the surface hardness of the casing specimens tested under WBM. The results also show that the specific wear factor (K) values of specimens tested under WBM are in general 2 to 4 times higher than those obtained under OBM. While K values under WBM increase with both the side load and RPM, those under OBM show a sharp decrease with RPM. This behavior under OBM is due to this lubricant’s higher viscosity and the change of lubrication regime from thin film to thick film lubrication at higher RPM. Scanning electron microscopy (SEM) and the digital microscopic imaging (DMI) of SM235-110 casing specimens show that an aggressive combination of adhesive, abrasive, and plastic deformation was observed under WBM, while the dominant wear mechanism under OBM is abrasive wear.

This paper presents a numerical study on the vertical (axial) and lateral (flexure) behavior of CFST (Concrete-Filled Steel Tube) columns with active hoop prestress; this transverse prestressing effect is achieved by bolting together two steel half-tubes. This study refers to new construction only (i.e., no retrofit). 12 prototype CFST column specimens (segments) are analyzed. These specimens differ in the prestressing force (3 levels) and in the gravity loading ratio (4 levels); they are selected to represent typical ground columns of mid-rise buildings. The structural behavior of these column specimens is simulated with a nonlinear model implemented in Abaqus; the concrete and steel behavior are described with a damage-plasticity and a plasticity model, respectively. Finally, the interface concrete-steel interaction is represented by a hard (compression-only) surface-to-surface contact model. The calculations involve three consecutive loading steps: (i) transverse prestress, (ii) axial force, and (iii) lateral loading (shear force and bending moment). The structural behavior of the CFST columns is deeply examined and discussed; the results show that their axial-flexural capacity is adequate. Noticeably, it is concluded that the overall benefits of prestressing the columns are only modest. Preliminary studies on the aforementioned mid-rise buildings equipped with the CFST columns show that their gravity and wind capacities are largely enough; conversely, their seismic capacity is sufficient for moderate seismic ground motions only.

A novel prediction model for crack development of reinforced concrete (RC) piles with localized chloride corrosion in marine environment is proposed. A discrete method is used to solve the corrosion pit radius model and a crack extension model is developed to investigate the initiation and extension of cracks. The maximum corrosion degree of reinforced concrete pile is predicted according to the limit crack criterion, and finally a sensitivity analysis is carried out on the important parameters of crack extension. The results show that the radius of corrosion pit, the depth corrosion pit and cross-sectional area loss of reinforcement gradually increase as the corrosion level increases. The loss of local reinforcement section at crack initiation decreases with the increase of the ratio of concrete cover to initial diameter, and increases with the increase of pitting factor. The required pit depth for reinforcement cracking increases with the increase of the ratio of concrete cover thickness to diameter. The loss of cross-sectional area of reinforcement and the radius of corrosion pit increase with the increase of initial diameter of reinforcement. Increasing the pitting factor will reduce the pit depth and make the crack width develop faster before reaching the limit crack width. Increasing the concrete cover thickness can provide an improvement in the propagation of cracks. A comparative analysis shows that the localized corrosion pattern is more in conformity with marine engineering practice.

Concrete-filled steel tube (CFST) members have been widely used in the field of civil engineering due to their advanced superior mechanical properties. However, internal defects such as concrete core voids and interface debonding are likely to weaken the load-carrying capacity and stiffness of these members, which affects safety and serviceability of CFST structures. Visualizing the inner defects of concrete core in CFST members have been a critical need in civil engineering construction, a travel time tomography (TTT) is introduced to quantitatively identify and visualize the sizes and positions of CFST members in this paper. Moreover, a parameter analysis is performed to investigate the relationship between TTT imaging qualities and influence factors, e.g. inversion parameters, defect sizes and positions. The effectiveness and accuracy of the TTT algorithm are verified by several numerical examples and the results demonstrate that TTT can identify the sizes and positions of concrete core void defects in CFST members efficiently and several inversion parameters including model weighting matrix and inversion grid size really pose a significant impact on the imaging results of CFST members. In addition, several optimum parameters are recommended to benefit the future study of the promising TTT approach for CFST members.

Q345 steel is widely used in the construction industry, vehicle manufacturing industry, bridge construction industry and many other aspects due to its excellent comprehensive performance. However, due to its high silicon content, direct hot-dip galvanizing will lead to a series of problems, such as easy peeling of the coating due to the "silicon reactivity". In this paper, we adopt the "two-step hot-dipping method", first hot-dip aluminizing and then hot-dip galvanizing, to isolate the substrate and zinc liquid direct contact, so as to avoid the occurrence of "silicon reactivity". Through the microstructure characterization, neutral salt spray corrosion experiments, electrochemical experiments, the results show that: Al-Zn composite coatings from the inside out were perpendicular to the substrate growth of loose Fe2Al5 layer and Al-Zn layer, outbursts generation; Al-Zn composite coatings resistance to neutral salt spray corrosion was far more than the substrate; Al-Zn composite coatings polarization curve corrosion potential than the substrate was lower than that of the substrate by 0.512V, showing a strong corrosion resistance. It shows extremely strong corrosion resistance.

At present, in the field of aviation industry, titanium alloy is mainly used to manufacture parts such as compressor disc, blade and casing of aircraft engine. When working, titanium alloy parts produce high temperature due to high-speed running friction, which makes the high temperature oxidation resistance and friction resistance of titanium alloy greatly reduced. When their working environment contains salt, titanium alloys are subjected to thermal corrosion, which limits their wider practical applications. This paper introduce the aluminide coating and its preparation methods. The characteristics and functional mechanism of three functional coatings for service environment, such as high temperature resistant alumina-based coating, thermal corrosion resistant alumina-based coating and wear-resistant alumina-based coating are summarized. Finally, the development direction of composite coatings of titanium and titanium alloys for complex service environment is prospected.

In this work, a systematic study was conducted on the fabrication of multi-material components obtained employing Laser-Powder Bed Fusion (L-PBF) technology. The idea of making multi-material components is a winning capability of additive technologies because it allows the fabrication of Functionally Graded Materials (FGMs) with the customization of parts according to different required properties. The transition from one material to another was achieved gradually and continuously within the same layer using ad-hoc equipment designed for L-PBF systems with a powder spreading technique based on coaters or rollers. The influence of the relative position of the different materials within the powder chamber and the geometry of the developed equipment on the metallurgical and mechanical properties of the manufactured samples was evaluated. The performed tests involved the use of two materials, a nickel-based superalloy, and a stainless steel, having different chemical, physical and mechanical properties to obtain gradual properties variation in the manufactured samples. Based on the results of post-process characterization obtained through metallographic, chemical, and mechanical analysis, the relative positions of the materials and the geometry of the developed equipment have a limited effect on the sample’s manufactured properties. The characteristics of the FGM zone depend on the nature of the employed powders, and its extent coincides with that defined during the design of the divider.

This paper describes the formulations for viscoplasticity of metals based on the Chaboche and Delobelle model. The implementations of the viscoplastic models were detailed herein and then implemented via user subroutines for material models (UMAT) in ABAQUS. Two typical metals, i.e., 316 Stainless Steel and Zircaloy-4, were chosen as examples and their viscoplastic behaviors were captured. Numerical simulations are compared to reported experiments to validate the models and the UMAT codes. Typical viscoplastic behaviors of both metals, such as stress relaxation and creep, were captured well against available experiments. We publicize all the data and codes via: https://github.com/XJTU-Zhou-group/ABAQUS_UMAT_316ss_Zr4.

In this work a solution-annealed AISI 316H grade austenitic stainless steel was studied in terms of investigating the electrolytic hydrogen charging effects on the resulting Charpy impact toughness and dry sliding tribological behavior. Conventional Charpy impact bending tests were employed to study the mechanical response of the investigated material to dynamic loading conditions, whereas dry linear sliding tribological tests were used to study the material friction and wear behavior. The obtained mechanical and tribological properties were correlated with corresponding fracture and tribological mechanisms determined from morphological observations of fracture surfaces and tribological tracks. The applied testing procedures were individually carried out for the non-hydrogenated, hydrogen-charged, and dehydrogenated material conditions. The observed changes of individual properties due to applied hydrogen charging were rather small which indicated good resistance of the solution-annealed AISI 316H steel against material degradation in currently used electrolytic hydrogenation conditions.

At Mae-Moh power plant, Thailand, superheater tubes, which are exposed in fly ash environ-ment, often degrade due to solid particle erosion. To extend the service lifetime of the superheater tubes, the high velocity oxy-fuel (HVOF) thermal spray technique is used to deposit a protective coating on the material, SA213-T22 steel. In this work, the solid particle erosion of the Co-28Cr and WC-12Co coatings was investigated using erodent particle impingement at the angles of 30o and 90o with an average particle size of 60 μm. The erosion behavior of SA213-T22 with and without Co-28Cr and WC-12Co coatings was explained using ductile and brittle erosion modes. The erosion test resulted in the brittle mode for both Co-28Cr and WC-12Co coatings, while SA213-T22 without coating indicated the ductile mode. On the investigation of surface morphology, the Co-28Cr coating showed mostly microcracks in contrast with the WC-12Co coating, fracture, de-bonding and deep cavities were also observed. Erosion resistance of the Co-28Cr coating was significantly higher than the WC-12Co coating, due to high hardness, low porosity and high density of the coating.

In metal continuous casting process is important to estimate the temperature evolution of casted section along machine from meniscus (point in which liquid metal is poured) to cutting machine where product is cut at commercial length. Particularly in the case of large sections, a convenient approximated model to achieve this goal with a feasible computational effort, is the so called travelling slice: the transversal section of casted product is subjected to different thermal boundary conditions (e.g. thermal flux, radiation, convection) that are found during the movement at constant speed from meniscus to the end of machine. In the case of an axisymmetric section, a comparison with the exact solution can be easily achieved. The article will show pros and cons of both, namely the far lower computational cost of travelling slice model without losing precision. Results confirm the validity of the travelling slice approach also at low casting speed and huge dimensions.

We present functionalization of AISI 316L surfaces by nanosecond Nd:YAG laser texturing in order to modify the surface morphology with crosshatch and dimple patterns. We performed tribological analysis under lubrication with sunflower and jojoba oil with and without addition of solid lubricant, MoS2 nanotubes. In connection to friction/wear response we analysed laser-textured surface wettability, oil spreadability and oil retention capacity. We have shown, that the crosshatch pattern generally exhibited lower friction than the dimples pattern, with the addition of MoS2 nanotubes not having any significant effect on the coefficient of friction under the investigated contact conditions. This was additionally with better oil spreadability and oil retention capacity results of crosshatch textured surface. Furthermore, texturing reduced wear of the stainless steel surfaces but led to approximately one order of magnitude larger wear rate of the steel counter-body, primarily due to the presence of hard bulges around the textured patterns. Overall, the crosshatch pattern showed better oil retention capacity and lower friction in combination with different vegetable oils, thus making it a promising choice for improving tribological performance in various environmentally friendly applications.

To weaken the harm of Al-Si coating and increase the strength of welded joint, variable thickness of Ni foil (Ni, an austenitic formation element) was added into the lap laser welding Al-Si coated 22MnB5 hot stamping steel/galvanized steel joints. The joints' weld appearance, microstructure, and mechanical properties were explored. The weld altered from X-shape to Y-shape with the increased thickness of Ni foil. During welding, Al-Si coating was melted and diluted into the welding pool, forming δ-ferrite (a rich-Al phase with low toughness and strength) in FZ and FB. This phase deteriorated the strength of the joints. After adding Ni, the amount and size of the δ-ferrite phase decreased. With a significant thickness of Ni foil, δ-ferrite would disappear. However, a new phase (FM, rich-Ni phase) probably formed except PM(a no or negligible Ni phase). The heat-affected zone (HAZ) on the side of 22MnB5 comprised a coarse martensite zone, refined martensite zone, martensite+ferrite zone, and tempered martensite zone from the FZ to the basic material. HAZ on the side of galvanized steel mainly contained ferrite and pearlite. After adding Ni foil, the strength of the joint was more than that without Ni. The maximum strength of the joint can be up to 679MPa because of the disappearance of δ-ferrite. Meanwhile, the toughness of the joint increased. The fracture mode was from three mixed fractures(cleavage, quasi-cleavage, and dimple) to one fracture(dimple).

In view of the limitations of the existing optimization method of suspender cable force, in order to improve the stress of suspender under completion state and avoid frequent adjustment of cable force and grid beam elevation during construction, a new method of cable force optimization is proposed. The article takes the longest large span arch bridge in the world, Pingnan Third Bridge, a Concrete-filled steel tube (CFST) arch bridge with a span of 575m as the engineering background combined with the finite element analysis and multi-objective optimization method. One cable force optimization method that suspender “Real-time correction during construction, in the process variable optimal and results reliable” during panel girder lifting of long span CFST arch bridges is clarified. Taking the panel girder weight and displacement during the construction as parameter variables, the displacement and unevenness of the panel girder under completion state as constraint conditions, the displacement and cable force during the hoisting construction as the objective equation, through the optimization of the objective equation, the suspender cable force and dis-placement of each hoisting section are calculated. The results show that it is feasible to introduce the optimization theory into the cable force optimization when lifting the panel girder. the segment displacement variation is minimized to meet the destination. The cable force distributed evenly under completion state of the bridge that further making sure the completion state satisfies the requirements. No repeating iteration is needed, thus avoiding cumberso me calculation, getting cable force once. With higher optimization efficiency and better effects, the method provides high value for the cable force calculation of same type bridge suspender construction and for guiding construction.

This paper offers a set of comprehensive guidelines aimed at facilitating the widespread adoption of hydrogen in the industrial hard-to-abate sectors. The authors begin by conducting a detailed analysis of these sectors, providing an overview of their unique characteristics and challenges. The paper delves into specific elements related to hydrogen technologies, shedding light on their potential applications and discussing feasible implementation strategies. By exploring the strengths and limitations of each technology, the paper offers valuable insights into its suitability for specific applications. Finally, through a particular analysis focused on the steel sector, the authors provide in-depth information on the potential benefits and challenges associated with hydrogen adoption in this particular context. By emphasizing the steel sector as a focal point, the authors contribute to a more nuanced understanding of hydrogen's role in decarbonizing industrial processes and inspire further exploration of its applications in other challenging sectors.

Although 7055 aluminum alloy is a deformed aluminum alloy and will show excellent mechanical properties after recrystallization after large deformation, it is a method to enrich its application range if rare earth is added and the rare earth phase dispersion is promoted by heat treatment. This article used optical microscopy, scanning electron microscopy energy dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD), micro Vickers hardness and room temperature stretching methods to study the as-cast 7055-xEr (x=0wt.%, 0.2wt.%, 0.4wt.%, 0.6wt.%, 0.8wt.%) aluminum alloy after being subjected to 460 oC×3h homogenization and 410 oC×1h solid solution+150 oC×12h aging treatment the changes in microstructure and properties. The results indicated that: when 0.2wt.%Er was added to 7055 aluminum alloy after solution at 410 oC×1h and aging at 150 oC×12h, the dendrite structure was significantly reduced, the grain thinning was obvious and the distribution was uniform, Al8Cu4Er phase appeared in the lamellar eutectic η-Mg(Zn,Al,Cu)2 structure at grain boundaries, and the hardness reached 168.8HV. The yield strength, tensile strength and elongation were 542.12Mpa, 577.67MPa and 8.36%, respectively.

This study investigated the mechanical properties and fatigue behavior of FH36 steel plate rolled in different directions. By adopting a sequential rolling process in the rolling direction (RD) and transverse direction (TD), the differences in properties between RD and TD were eliminated, resulting in nearly identical tensile properties. The steel plate exhibited a yield strength of approximately 420 MPa, a tensile strength of approximately 506 MPa, and an elongation of approximately 25%. Fatigue tests conducted at room temperature and -60℃ showed a fatigue limit of the maximum stress of 488 MPa at room temperature and 500 MPa at -60℃, indicating improved low-temperature fatigue performance. The fracture surfaces displayed distinct characteristics, such as oblique shearing fractures for high-cycle fatigue and cup-cone shape fractures for low-cycle fatigue. The fatigue source zone were both on the surface of the specimens. As the maximum stress increased, the area of the crack propagation zone for high-cycle fatigue decreased, while the area of the final fracture zone, the number of dimples and the proportion of the LAGBs increased.

The welding and construction processes of H-type thick-plate-bridge steel involve complex multi-pass welding processes, which is difficulty to ensure its welding performance. Accordingly, it is crucial to explore the inherent correlation among the welding processes parameters and welding quality, and applied it into the welding robots, eliminating the instability from manual welding. In order to improve the welding quality, the GMAW (Gas Metal Arc Welding) welding process parameters are simulated using the Q345qD bridge steel flat joint model. Four welds with X-shaped grooves are designed to optimize the parameters of welding current, welding voltage, and welding speed. The optimal welding process parameters are investigated through thermal-elastic-plastic simulation analysis and experimental verification. The results indicate that when the welding current is set to 230A, the welding voltage to 32V, and the welding speed to 0.003m/s, the maximum deformation of the welded plate is 0.52mm, with a maximum welding residual stress of 345MPa. Both the simulation results of multi-pass welding and experimental tests meet the welding requirements, as they show no excessive stress or strain. These parameters can be applied into building large steel frame bridges with welding robots, improving the quality of welded joints.

Currently, the design of the concrete mix is an important part of the environmental problem. In front of this question, engineers face a major challenge that is addressed in two ways. On one hand, how do they use its component materials to improve its mechanical properties, on the other hand how do they use less polluting materials? Hence, in an environmental and economical view, laboratory tests were carried out on samples of concrete reinforced with smooth steel fiber extracted from the waste tires, in order to assess its impact and to prove its mechanical feasibility for these purposes. Consequently, laboratory results have shown satisfactory improvement in the behavior of concrete under compression loads in the elastic stage and an increase in ductility and toughness of the matrix in the plastic stage. Besides, taking into account the discontinuity and the structural disturbances observed during the loading of samples in the post-elastic state, a method has been proposed to calculate "the effective toughness and toughness Index of fiber concrete; on the other hand, this method has helped to better optimize length and slenderness of fibers for better use of this recycled material

Limited availability of expensive alloying elements elevates low-alloyed steels to a unique position in the field of lightweight construction and mass production. Quenching and partitioning (Q&P) heat treatments of low-alloyed steels with exceptional property combinations are particularly promising. In this study, we characterize for the first time a new low-alloyed steel to be processed by Q&P heat treatments. In combined experimental and numerical studies, we design a novel approach that effectively combines the short cycle times of press hardening with the excellent property profiles of Q&P-treated steels. We identify appropriate transformation parameters for Q&P heat treatments by dilatometric studies and we adjust a number of reference conditions with different isothermal holding times. By means of SEM analysis and XRD measurements, we show that different fractions of retained austenite result in different mechanical properties. Initial numerical designs of the process can identify varying temperature profiles and cooling rates depending on the position in the die. The results show that the geometry of the part plays a minor role, but the die temperature is the dominant factor for successful partitioning directly in the press hardening process.

Current conventional methods of evaluating microstructures are characterized by a high degree of subjectivity and a lack of reproducibility. Modern machine learning (ML) approaches have already shown great potential in overcoming these challenges. Once trained with representative data in combination with an objective ground truth, the ML model is able to perform a task properly in a reproducible and automated manner. However, in highly complex use cases, it is often not possible to create a definite ground truth. This study addresses this problem using the underlying showcase of microstructures of highly complex quenched and quenched and tempered (Q/QT) steels. A patch-wise classification approach combined with a sliding window technique provides a solution for segmenting entire microphotographs where pixel-wise segmentation is not applicable due to the problem of reproducibly creating unambiguous training masks. Using correlative microscopy, consisting of light optical microscope (LOM) and scanning electron microscope (SEM) micrographs as well as corresponding data from electron backscatter diffraction (EBSD), a training dataset of reference states that covers a wide range of microstructures was acquired in order to train accurate and robust ML models. Despite the enormous complexity associated with the steels treated here, classification accuracies of 88.8% in the case of LOM images and 93.7% for high-resolution SEM images were achieved. These high accuracies are close to super-human performance, especially in consideration of the reproducibility of the automated ML approaches compared to conventional methods based on subjective evaluations through experts.

Modified aluminum slag (MAS) was applied as an adsorbent for Congo red (CR) prepared by the hydrothermal treatment of Ca (OH) 2. At 25 ℃, with a MAS dosage of 0.3g, initial CR concentration of 100 mg/L and initial pH=5, and the adsorption time was 40 min, the CR removal efficiency was 98.41%. The adsorption trend of CR conformed to the second-order kinetics, and the adsorption isotherm follows the Freundlich isotherm model. Compared with RAS, MAS has a larger pore volume and specific surface area. The mechanism of action of MAS on CR was the interaction between membrane diffusion and internal diffusion, and the adsorption rate during the membrane diffusion was the fastest.

In recent years, in addition to the commonly known wire-based processes of Directed Energy Deposition using lasers, a process variant using the electron beam has also developed to industrial market maturity. The process offers particular potential for processing highly conductive, reflective or oxidation-prone materials. However, for industrial usage there is a lack of comprehensive data on performance, process limits and possible applications. The present study deals with this problem using the example of the high-strength aluminum bronze CuAl8Ni6. Multi-stage test welds are used to determine the physically possible process limits and draw conclusions about the suitability of the parameters for additive manufacturing. For this purpose, optimal ranges for energy input, possible welding speeds and the scalability of the process were investigated. Finally, additive test specimens in the form of cylinders and walls are produced and the hardness profile, microstructure and mechanical properties are investigated. It is found that the material CuAl8Ni6 can be well processed by wire electron beam additive manufacturing. The microstructure is similar to a cast structure, the hardness profile over the height of the specimens is constant and the tensile strength and elongation at fracture values achieved correspond to the specification of the raw material.

The possibility of increasing the resource of steel fingers working in tandem with bronze bushings by plasma-electrolytic nitrocarburizing of the surface of medium carbon steel is shown. The phase composition, microhardness, morphology and surface roughness were studied. Tribological tests were carried out under dry friction conditions according to the shaft-pad scheme. It has been established that plasma-electrolytic nitrocarburizing of the surface of medium carbon steel at a temperature of 700 °C for 5 minutes leads to a decrease in a friction coefficient by 2.3 times, weight wear of steel by 24.9 times, and bronze counterbody by 5.9 times. At the same time, the contact stiffness increases 2.6 times. The type of wear is fatigue with dry friction and plastic contact. Changes in tribological characteristics are associated with the high hardness of the hardened steel surface together with the influence of dispersed nitrides and iron carbonitrides distributed in it.

This paper presents a new method of preparing a coating on the Ti65 titanium alloy by a two-step procedure comprising hot-dipped aluminum and solid carburization. The effects of the carburization in the presence of NaCl deposit at 810oC have been systematically studied. In this article, the microstructure, morphology, phase composition of the coating, and the corrosion products were investigated by SEM, EDS, and X-ray diffraction. Results indicated that the corrosion resistance of hot dip aluminum/carburizing composite coating was not significantly enhanced by hot dip aluminum coating. This can be attributed to the formation of TiC and Ti3AlC after carburization, which promoted the formation of loose and unprotected TiO2 in the coating during molten salt corrosion. In addition, the oxidation of the carbon atom into CO2 /CO leaded to a high concentration of vacancy in the coating, creating channels for NaCl to penetrate the coating and accelerated the corrosion rate.

The materials used as corrosion inhibitors are [Zn-Al-Cl], [Mg-Al-Cl], [Ni-Fe-Cl], and [Co-Fe-Cl] layered double hydroxides (LDHs). They were synthesized by coprecipitation and characterized by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), and thermal anal-yses. The efficiency of these corrosion inhibitors on mild steel in concentrated hydrochloric acid (18.5%) at 60°C (chemical pickling conditions of steel) was studied using electrochemical and gravimetric methods for different concentrations. The surface morphology and composition were examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), respectively. The inhibitory efficiency in the case of 1.2 g.L-1 LDH was found to be 83.33%, 83.65%, 68.38%, and 74.73% for [Ni- Fe-Cl], [Zn-Al-Cl], [Co-Fe-Cl], and [Mg-Al-Cl], respectively.

The cast grains of the 7055 aluminum alloy were refined by adding Sm + Er, and the proper heat treatment procedure was utilized to further precipitate the rare earth phase in order to increase the alloy's strength and toughness. The grain size, microstructure and phase were characterized by optical microscopes (OM), Scanning electron microscopy - energy spectrum (SEM-EDS), XRD diffractometer (XRD). The macroscopic hardness, yield strength and tensile strength of alloy materials were measured by hardness meter and universal electronic tensile machine. The results shown that the as-cast sample and the heat treatment sample all exist Al10Cu7Sm2 and Al8Cu4Er rare earth phase; But after heat treatment, the volume percentage of the rare earth phase dramatically increased and the dispersion was more unified. When 0.3wt.%Sm and 0.1wt.%Er were added, the grain size could be refined to 53μm. With the increase of the total content of rare earth elements, the refining effect first increased and then decreased. Under 410 oC solid solution for 2h + 150oC aging for 12h, the macroscopic hardness, yield strength, tensile strength and elongation of 0.3wt.%Sm + 0.1wt.%Er+7055 as-cast sample were 155.8HV, 620.5Mpa, 658.1Mpa, and 11.90%, respectively.

The effects of partial replacement of Si by Al on the microstructure, tensile properties, and Charpy impact toughness were investigated using 0.2%C-Si/Al-Mn-Cr-B TRIP-aided martensitic steels. The impact toughness was related to the microstructural and mechanical properties. The partial re-placement decreased the volume fraction of retained austenite and increased the mechanical stabil-ity, accompanied by softening and an increase in the volume fraction of the primary martensite. Resultantly, the partial replacement decreased strength and ductility. The impact absorbed energy (value) at 25 C was slightly increased by the partial replacement. The increased impact absorbed energy was mainly caused by high crack/void propagation energy due to the softened primary martensite and a small contribution of the stabilized retained austenite. The 50% shear fracture ductile-to-brittle transition temperature was marginally raised by the partial replacement. The raised transition temperature was mainly associated with an increase in a unit crack path of qua-si-cleavage/cleavage fracture.

The response of structures under pulse-like ground motions is characterized by the large amount of energy input in a few cycles. Consequently, structures with insufficient strength may suffer severe damage owing to excessive deformation. In a previous paper, the energy-based prediction procedure for the peak and cumulative response of a reinforced concrete (RC) frame building with steel damper columns was proposed (Fujii and Shioda, 2023). Although this procedure was verified by comparison to the nonlinear time-history analysis (NTHA) results, the performance of the proposed procedure with pulse-like ground motion records has not been verified yet. In this study, the accuracy of the energy-based prediction procedure for an RC frame building with steel damper columns was investigated by considering pulse-like ground motions. The numerical analysis results reveal that the accuracy of the predicted peak response is satisfactory, which agrees with the results of the author’s previous study. However, the accuracy of the predicted total input energy to the building model depends on the ratio of the pulse period of the ground motion to the effective fundamental period of the building model. The reasons for this underestimation of the total input energy are discussed in this paper.

Large aluminum alloy ring forgings are the core components of heavy-duty rocket fuel storage tanks, and the large residual stress inside the rings leads to poor shape accuracy of large thin-walled parts. The initial stress of the 2219 aluminum alloy ring blank was tested using the drilling method, and the creep constitutive coefficient of the 2219 aluminum alloy was determined through stress relaxation tests. The numerical simulation processes of thermal stress relief (TSR), vibration stress relief (VSR), and thermal-vibration stress relief (TVSR) were compared and established. Through the correlation analysis between the actual measurement results of residual stress and the simulation results, it can be seen that the strong correlation in three directions at each measurement point accounts for over 37.5%, and the moderate correlation accounts for over 62.5%. This indicates that the numerical simulation model of 2219 aluminum alloy ring containing initial residual stress can accurately reflect the size and distribution of residual stress inside the actual ring. The simulation results show that the derived constitutive model can describe the stress relaxation process of TVSR by combining a single thermal time effect stress relaxation constitutive theory with a VSR plastic deformation material model. The simulation models established above were used to calculate the residual stress homogenization ability of three types of aging. The results showed that VSR, TSR, and TVSR can homogenize and reduce the residual stress field inside the ring, improve the distribution of residual stress inside the ring, and have a better overall homogenization ability of TVSR. The VSR control has a certain effect on reducing and homogenizing residual stress, but compared with TSR and TVSR, the reduction and homogenization ability of residual stress control is limited. The homogenization control effect TVSR>TSR>VSR, and the maximum equivalent stress homogenization rates of VSR, TSR, and TVSR are 52.8%, 80.6%, and 82.2%, respectively. Then, numerical simulation technology is used to study how the initial residual stress in the blank will cause the deformation of the ring during the thin-walled machining process. The roundness error theory of the minimum containment area method is applied to evaluate the deformation degree during the thin-walled numerical machining process, and the TVSR method is used for stress regulation. The deformation law of the thin-walled machining of the ring under different aging parameters is studied.

The microstructure and hardness along the thickness direction of a water quenched, high-strength thick plate with a thickness of 40 mm were investigated with three specimens from the thick plate: surface, 1/4t, and 1/2t (center) thickness, and the phase transformation behavior of the thick plate according to the cooling rate was analyzed through dilatometric experiments. Finally, the cooling rate for each thickness of the thick plate was estimated by comparing the microstructure and hardness of the thick plate along the thickness with those of the dilatometric specimens. Martensite microstructure was observed on the surface of the water quenched thick plate due to the fast cooling rate. On the other hand, an inhomogeneous microstructure was transformed inside the thick plate due to the relatively slow cooling rate and central segregation of Mn. A small fraction of bainite was shown at 1/4t thickness. A banded microstructure with martensite and bainite resulting from Mn segregation was developed at 1/2t; that is, the full martensite microstructure was transformed in the Mn-enriched area even at a slow cooling rate due to high hardenability, but a bainite microstructure was formed in the Mn-depleted area owing to relatively low hardenability. A portion of martensite with fine cementite at the surface and 1/4t was identified as auto-tempered martensite with a Bagaryatskii orientation relationship between the ferrite matrix and cementite. The microstructure and hardness as well as dilatation were investigated at various cooling rates through a dilatometric experiment, and a continuous cooling transformation (CCT) diagram was finally presented for the thick plate. Comparing the microstructure and hardness at the surface, 1/4t, and 1/2t of the thick plate with those of dilatometric specimens cooled at various cooling rates, it was estimated that the surface of the thick plate was cooled at more than 20 oC/s, whereas the 1/4t region was cooled at approximately 5 ~ 10 oC/s during water quenching.

Cathodic protection is widely used to protect metal structures from corrosion and is commonly applied on marine structures in seaports using sacrificial galvanic anodes. These anodes, either in Zinc, or preferen-tially nowadays in Al-Zn-In alloys, are expected to corrode instead of the metal to be protected. This leads to the release of specific dissolved species, Zn2+, Al3+, In3+ and solid phases like Al(OH)3. Few studies were conducted on the effects of anodes on marine organisms and concluded that further detailed investiga-tions are needed in controlled environments. We therefore propose an experimental approach to evaluate the effects of Zn and Al-Zn-In anodes on oysters stabulated in tanks, under conditions approaching those used in the ports. We chose a non-targeted metabolomic approach, using UHPLC coupled to HRMS, to study the effects on the entire metabolome, without any a priori. A modelling study of the chemical species, corresponding to the deg-radation products of the anodes, likely to be present near the exposed oysters, was also included. We identified 16 and 2 metabolites modulated by Zn- and Al-Zn-In-anodes respectively, involved in bi-ological functions, such as energy metabolism, osmoregulation, oxidative stress, lipid, nucleotide nucle-oside and amino acid metabolisms, defense and signaling pathways.

Damage assessment is one of the most crucial issues for bridge engineers, especially for existing steel bridges. Among several methodologies, the vibration measurement test is a typical approach in which the natural frequency variation of the structure is monitored to detect the existence of damage. However, locating and quantifying the damage is still a big challenge. In this regard, the artificial intelligence (AI)-based approach seems a potential way to accomplish those obstacles. This study deploys a comprehensive campaign to determine all dynamic parameters of a pre-damage steel truss bridge structure. Based on the results of mode shape, natural frequency, and damping ratio, a finite element model (FEM) is created and keeps updating. The artificial intelligence network's input data will be analyzed and evaluation from damage cases. The trained artificial neural network model will be curated and evaluated to confirm the approach's feasibility. During the actual operational stage of the steel truss bridge, this damage assessment system is showing good performance in terms of monitoring the structural behavior of the bridge under some unexpected accidents.

Friction Stir Welding is a suitable solid-state joining technology to connect dissimilar materials. To produce an effective joint, it requires a phase of optimization which leads to the definition of process parameters such as pin geometry, tool rotational speed, rotation direction, welding speed, thickness of the sheets or tool tilt angle. The aim of this review is to present a complete and detailed frame of the main process parameters and their effect on the final performance of a friction stir welded joint in terms of mechanical properties and microstructure. Particularly, the attention was focused on the connection between different aluminum alloys. Moreover, the experimental results were correlated to the development and the applications of tools, which can effectively use in the design of the manufacturing process, such as finite element analyses, artificial neural networks, statistical studies. The review wants to be also a point of reference to identify the best combinations of process parameters based on the dissimilar aluminum to be joined.

Nitriding has long been used to engineer the surfaces of engineering steels to improve their surface and subsurface properties. The role of the surface compound layer (’-Fe4N and/or -Fe2-3N) in improving the tribological and corrosion resistant properties of nitrided steels has been established. However, there have been very few studies on the response of the compound layer to tribocorrosion in corrosive environments. In this work, the tribocorrosion behaviour of a 5 m thick ’-Fe4N nitride layer produced on mild steel (MS) by plasma nitriding has been studied in a NaCl containing solution under various electrochemical conditions. The results show that at a cathodic potential, where mechanical wear is predominant, the total material removal (TMR) from the ’-Fe4N layer is 37% smaller than that from the untreated MS, and at open circuit potential, TMR from the layer is 35% smaller than that from the untreated MS, while at an anodic potential, the ’-Fe4N layer can reduce TMR from mild steel by 87%. The beneficial effect of the ’-Fe4N nitride layer in improving the tribocorrosion behaviour of mild steel is derived from its high hardness and good corrosion resistance in the test solution and its ability to resist both mechanical wear and chemical wear.

Improper lifting measures of long-span spatial steel structures during construction process may delay the construction period and even cause safety accidents. Few studies on long-span spatial steel structures considered time-varying mechanical characteristic during construction process. In order to achieve safe and efficient installation in a long-span spatial steel structure, this research presents a time-varying mechanical analysis of the synchronous and asynchronous integral lifting and a single and interlaced point’s asynchronous integral lifting analysis method of a long-span spatial steel structure. The results showed that in the case of asynchronous lifting of single point, the displacement influence on other members is related to the distance. The closer the distance from the lifting point, the greater the influence. In asynchronous integral lifting, the lifting point with large lifting force is first installed to the specified position, and the lifting point with small lifting force is installed to the specified position.

In this paper, through high-temperature tensile tests of 55NiCrMoV7 steel, the high-temperature fracture behavior, microstructure evolution and carbide distribution characteristics of both thermal-mechanical coupling zone (fracture zone) and thermal stress zone (clamping zone) at different temperatures were studied. Intrinsic relationship between high temperature fracture and carbides types, distribution and size were revealed and evolution mechanism of microstructure near cracks in 55NiCrMoV7 hot-working die steel during high temperature deformation was clarified. Samples were stretched at different temperatures from 25 °C to 700 °C, and microscopic examinations were carried out by using SEM and TEM. The results showed that: With the increase of temperature, tensile strength and yield strength decreased, elongation and reduction of area increased, and fracture mode changed from brittle fracture to ductile fracture by transition temperature at about 400℃. During high temperature deformation, the grain dislocation density decreased, the tempered martensite decomposed, recovered, recrystallized, and then grain grew. M7C3 and M23C6 carbides precipitated and grew along the grain boundary, and a small amount of fine granular MC carbides were dispersed in the grain. The work done by the external force on the deformation zone would cause the temperature of it to be higher than tensile temperature, which provides thermodynamic conditions for the re-dissolution of small carbides near the fracture zone and the grain growth of large carbides, resulting in the decrease of small carbides and increase of large carbides in thermal-mechanical coupling zone.

A reliable finite element procedure to simulate shear-dominated ductile fracture in large-scale, thin-walled steel structures is still evolving due primarily to the challenges in determining the fracture criterion of steel materials under complex stress states. This paper aims to examine the accuracy of the modified Gurson-Tvergaard-Needleman (GTN) model considering the shear failure in simulating ductile fracture of steel plate structures under quasi-static punch loading. The modified GTN damage models are performed by ABAQUS user defined material subroutine (VUMAT). The void related parameters and shear damage parameters of Xue’s and N-H modified GTN models are calibrated from test specimens with various geometries corresponding to different stress triaxiality and shearing conditions. The damage evolution associated with the shearing of voids in the modified GTN models has strong influences on the stress triaxiality versus equivalent plastic strain under complex stress states, especially for the shear dominated loading conditions. Based on the original GTN model, Xue’s model, and N-H modified GTN model with calibrated material parameters, a numerical comparative study examines the ductile fracture of steel non-stiffened plate and stiffened plate under punch loading. Benchmarked against the experimental studies, the numerical simulations demonstrate that the shear driven void evolution in the modified GTN model imposes significant effects on the load-displacement responses, as well as the onset and extension of ductile fracture in steel plates under punch actions. The N-H modified model with calibrated shear damage parameters shows a better correlation with the ductile fractures in steel plates observed in the experiment, than the original GTN model and Xue’s modified GTN model. As a result of this study, the modified GTN model considering the shear failure can be applied for practical applications in the crashworthiness assessment of ship collision and grounding.

Elastic properties of materials and their changes with temperature are important for their applications in engineering. A study on the influence of phase composition of AISI 4130 alloy on Young's modulus (Ed), shear modulus (Gd), and damping (Q-1) was carried out by Impulse Excitation Technique (IET). The material characterization was carried out using confocal microscopy, XRD, MET, HV, and dilatometry. A stable structure, composed of ferrite (BCC) and pearlite (α-Fe+Fe3C), was obtained by annealing. Metastable structure of martensite (BCT) was obtained by quenching. The Ed, Gd, and Q-1 were measured, varying the temperature from RT to 900 °C. The values of Ed and Gd, at RT, were determined as 201.5 and 79.2 GPa (annealed), and 190.13 and 76.5 GPa (quenched), respectively. In the annealed steel, the values Ed and Gd decrease linearly on heating up to 650 °C, with the thermal expansion. In the quenched steel, weak changes in the dilatometric curve, Ed, Gd, and Q-1, in the range of 350-450 °C, indicated decompositions of the martensitic phase. Sharp decrease in the moduli and high peak of Q-1, was observed for both samples around 650-900 °C, revealing low lattice elastic stability of the phases during transformations α(BCC)+Fe3C↔γ(FCC).

In this paper, a new method by combining cold drawing and martensitic transformation was proposed to produce ultrahigh-strength steel wire, and the effect of austenitizing heating rate on microstructure and mechanical properties was studied. Compared with Muffle furnace heating, salt bath heating has a much higher austenitizing heating rate, which is beneficial to obtain ultrafine-grained martensite for steel wire with a larger section. By salt bath hardening and low-temperature tempering, an ultrahigh strong (strength of 2.48 GPa) and tough (elongation of 6.0%) steel wire was produced. Moreover, to explore whether is it possible to replace long-time low-temperature tempering with short-time tempering at elevated temperatures to improve the tempering efficiency, the effect of tempering time on the evolution of microstructure and mechanical properties of the steel wires tempered at 350 °C was systematically studied. The results demonstrate that tempering at 350 °C for 30 s can endow the steel wire with comparable mechanical properties to that of the one tempered at 250 °C for 2 h. With tempering time prolonging, the strength decreases gradually with the precipitated phase transition from χ-Fe5C2 carbide into θ-Fe3C carbide and coarsening, which plays a major role in the strength decrease.

To achieve the required mechanical properties in the heat treatment of steel, it is necessary to have an adequate cooling rate and to achieve the desired final temperature of the product. This should be achieved with one cooling unit for different product sizes. In order to provide high variability of the cooling system, different types of nozzles are used in modern cooling systems. Designers often use simplified, inaccurate correlations to predict the heat transfer coefficient, resulting in oversizing of the designed cooling or failure to provide the required cooling regime. This typically results in longer commissioning times and higher manufacturing costs of the new cooling system. Accurate information about the required cooling regime and the heat transfer coefficient of the designed cooling is critical. This paper presents a design approach based on laboratory measurements. Firstly, the way to find or validate the required cooling regime is presented. The paper then focuses on nozzle selection and presents laboratory measurements that provide accurate heat transfer coefficients as a function of position and surface temperature for different cooling configurations. Numerical simulations using the measured heat transfer coefficients allow the optimum design to be found for different product sizes.

In this study, the Bohler K 190 steel was used. The steel was manufactured by the powder metallurgy (PM) process. The boronizing process was carried out in the range of 1173 to 1323 K, for 1-10 h. The samples were boronized in solid medium, called the Durborid powder mixture. For the microstructural observations, the scanning electron microscopy was utilized for determining the morphology of interfaces and measuring the layers’ thicknesses. The phase composition of boride layers was also determined with X-ray diffraction analysis. To investigate the redistribution of chemical elements redistribution during the boronizing process, the EDS mapping and EDS point analysis were used. The boride layers were constituted by FeB and Fe2B phases except for 1173 K for 1 h. The values of Vickers microhardness of Fe2B, FeB and transition zone were estimated. Finally, to assess the boron activation energies in FeB and Fe2B, the so-called integral method was applied and the results in terms of activation energies were confronted with the literature data.

A large amount of steel slag (SS) and CO2 are generated in the steelmaking process. The indirect CO2 capture using SS is a promising way for co-treatment of the wastes. Ammonium salt solution is widely used to extract Ca2+ from the SS since it is recyclable. Several works have focus on improving the carbonation rate by adjusting various parameters (e.g., temperature and pH). However, there is little detail information about the associating behaviors and interaction strength between the various ions in the ammonia solution during the carbonation process. In this work, the Ca2+–CO32-–NH4+–Cl-–H2O system was established by using Material studio software. The effects of temperature and concentration of CO32- on CaCO3 growth were explored at the atomic scale by calculating the binding energy, mean square displacement, and diffusion coefficient between particles. Furthermore, the microstructure, bonding characteristics, and occurrence behavior of each particle were studied though molecular dynamics simulation methods. The results showed that with the increase of temperature (20–80 ℃), the binding ability and diffusion coefficients of Ca2+ and CO32- increase in the system, which is beneficial to the formation of CaCO3 clusters. With the increase of the concentration of CO32- (15–25 vol.%), the binding ability and diffusion coefficient of Ca2+ and CO32- in the system are enhanced, which is beneficial to the formation of CaCO3 clusters.

This paper presents the results of an experimental and analytical study on the behavior of cold-formed thick-walled steel plates connected by a single bolt under double shear. Experimental studies were conducted on a total of 54 bolted connections fabricated from two thickness of cold-formed thick-walled steel plates with the nominal thickness of 6 mm and 10 mm. The effects of end distance, edge distance and steel plate thickness were investigated on the bolt bearing behavior. Codes of (modified) ANSI/AISC 360-16 and EN1993-1-8 were applied to predict failure modes and bearing resistance of connections and the predictions were compared with that of measurements. A method was proposed to calculate the elongation of bolt hole at ultimate load. The studies show that fractures occurred on shear planes of specimens failed by shear out due to reduced ductility caused by cold forming process. The modified ANSI/AISC gives the most accurate predictions of failure modes and bearing resistance. However, the bearing resistance will be overestimated if the reduction in area of shear planes caused by occurrence of fracture is ignored for specimens with end distance being higher than 2.0d0 and a reduction factor is needed for calculating bearing resistance of connections. The method proposed in our paper can predict the elongation of bolt hole very well.

Heat-treated aluminum-silicon (Al-Si)-based alloys have dominated the cast lightweight alloy industry for several decades. However, in the last decade, Al-Ce-based alloys have shown promise in replacing Al-Si alloys due to their ability to remove the need for costly heat treatments. Since the properties of Al-Ce alloys depend on the as-cast microstructure, it is important to characterize the solidification kinetics of these alloys. Therefore, this study focused on characterizing the solidification of a near eutectic Al-Ce alloy with additions of Ni and Mn. The alloy was cast in a wedge mold configuration, resulting in cooling rates between 0.18 and 14.27 °C/s. SEM coupled with EDS and DSC techniques characterized the evolution rate of solid phases. The SEM/EDS data revealed that an Al10CeMn2 phase is present at higher cooling rates. At lower cooling rates, near the center of the casting, a proeutectic Al23Ce4Ni6 phase was more present. It was observed that up to 2.6 at. % of Mn was dissolved in this proeutectic Al23Ce4Ni6 phase, thereby removing a large portion of the available Mn for forming the Al10CeMn2 phase. DSC analysis showed differences in the samples' liquidus temperatures which is indicative of compositional variations. Inductively coupled plasma atomic emission spectroscopy (ICP-OES) and Scheil solidification simulations correlated the compositional differences to phase formation, which agreed with the SEM and DSC results. This experimentation provides insight into novel Al-Ce-Ni-Mn alloys and where their potential lies in industrial applications.

There is a fast-growing interest in the use of selective laser melting (SLM) for metal/alloy additive manufacturing. Our current knowledge of SLM printed 316 stainless steel (SS316) is limited and sometimes appears sporadic, presumably due to the complex interdependent effects of a large number of process variables of the SLM processing. This is reflected from the discrepant findings in the crystallographic textures and microstructures in this investigation with those reported in the literatures, which also vary itself. The as-printed material is macroscopically asymmetric in both the structures and crystallographic textures. The <101> and <111> crystallographic directions align parallel with the SLM scanning direction (SD) and build direction (BD), respectively. Like-wise, some characteristic low angle boundary features are reported crystallographic, while this investigation unequivocally proves them non-crystallographic since they always maintain an identical alignment with the SLM laser scanning direction irrespective of the matrix material’s crystal orientation. There is also 500±200 nm columnar or cellular features, depending on the cross-section, generally found all over the sample. These columnar or cellular features are formed with walls made of dense packing of dislocations entangled with Mn, Si and O enriched amorphous inclusions. They remain stable after the ASM solution treatments at 1050 °C temperatures, and therefore, are capable of hindering boundary migration events of recrystallization and grain growth. Thus, the nanoscale structures can be retained at high temperatures. Large 2-4 µm inclusions form during the solution treatment, within which the chemical and phase distribution are heterogeneous.

Hyper duplex stainless steels, HDSS, are a new alloy group of duplex stainless steels with the highest corrosion resistance and mechanical properties among the existing modern stainless steel. Due to the addition of extra high content of alloying elements, e.g. Cr, Ni, Mo, etc., the crystallization behavior of the δ-ferrite from the liquid is of vital importance for controlling the steel properties. In this work, the effect of cooling rate (i.e. 4°C/min and 150 °C/min) on the growth process of δ-ferrite in S33207 during the solidification process was investigated using high-temperature confocal scanning laser microscopy (HT-CLSM) in combination with electron microscopes and thermodynamic calculation. The results showed that the solidification mode of S33207 steel was a ferrite-austenite type (FA mode). L→δ transformation occurred at a certain degree of supercooling, and merging occurred during the growth of δ phase dendrites. Similar microstructures were observed after solidification under these two different cooling rates. The variation of area fraction of δ ferrite at the free surface and temperature as well as time during solidification of S33207 steels were calculated at different cooling rates of 4 °C/min and 150 °C/min, respectively. The current HT-CLSM study provides in-situ experimental evidence to confirm that a low cooling rate favored the growth of primary δ-ferrite, whereas a high cooling rate favored the nucleation of primary δ-ferrite during the solidification process. The post-microstructure as well as composition evolution is also briefly investigated. This work shed light on the real time insights for the crystallization behavior of hyper duplex stainless steels during solidification, which aims to contribute to the process control of manufacturing of this steel grade.

In this study composite with alternate layers of 5056 and 1580 alloys was manufactured by wire arc additive manufacturing technology. It is shown that increased strength characteristics of composite material can be obtained due to deformation treatment by high-pressure torsion (HPT) technique. The microstructure and mechanical properties of the HPT-processed material in different structural states were investigated. The HPT-processed material exhibits high value of ultimate tensile strength (~ 770 MPa) but low ductility. Short-term annealing at 250 oС and additional deformation by HPT to 0.25 of revolution at room temperature resulted in a slight decrease in material’s strength to ~ 700 MPa but provided ductility ∼ 9%. Physical mechanisms to improve plasticity in correlation with microstructure evolution is discussed.

This paper mainly used database technology, machine learning, thermodynamic calculation, experimental verification, etc., on integrated computational materials engineering. The interaction between different alloying elements and the strengthening effect of precipitated phases are investigated mainly for martensitic ageing steels. Modelling and parameter optimization were performed by machine learning, and the highest prediction accuracy was 98.58%. Investigated the influence of composition fluctuation on performance and correlation tests to analyze the influence of elements from multiple perspectives. Furthermore, screen out the three-component composition process parameters with composition and performance with high contrast. Thermodynamic calculations studied the effect of alloying element content on the nano-precipitation phase, Laves phase, and austenite in the material. The heat treatment process parameters of the new steel grade were also developed based on the phase diagram. A new type of martensitic ageing steel was prepared by selected vacuum arc melting. The sample with the highest overall mechanical properties had a yield strength of 1887 MPa, a tensile strength of 1907 MPa, and a hardness of 58 HRC. The sample with the highest plasticity had an elongation of 7.8%. The machine learning process for the accelerated design of new ultra-high tensile steels was found to be generalizable and reliable.

In this study, we investigated the inhibiting effect of Dioscorea spp leaf extracts on the corrosion of mild steel in selected media using the weight loss method. The mild steel samples were pre-weighed and immersed in NaOH, NaCl and H₂SO₄ solutions respectively containing the leaf extracts, with the control samples immersed in solutions of the media containing no extract. The samples were allowed to stand for 672 hours, with a set of samples from each environment withdrawn at intervals of 168 hours for corrosion characterization. The results obtained from all the environments indicate that the corrosion rate increased as concentrations of Dioscorea spp increased. Results also confirmed that the extract was an effective and excellent inhibitor in the alkaline, salt, and acidic media. Conclusively it was proven that the higher concentration of Dioscorea spp leaf extracts in the media had the best inhibition characteristic on the mild steel in the selected environments. The results show good potential for application in manufacturing industries. The microstructure analysis of the various test coupons in the test media should be carried out to reveal the influence of adding the leaf extracts to the stimulated media on the grain structure distribution of the mild steel.

The organic coating of bridge steel girders is subjected to physical scratches, corrosion, and aging in natural weathering. The breakdown of the coating may cause serviceability and safety problems if left unnoticed. A hyperspectral imaging method is proposed to detect the condition of steel coatings based on coating-responsive features in reflectance spectra. A field test was conducted on the real-world bridge which shows obvious signs of degradation. The hyperspectral signature enables an assessment of the coating health and defect severity. The results indicated that the coating scratch can be effectively located in the domain of a hyperspectral image and the scratch depth can be determined by mapping a scratch depth indicator (SDI=R532nm / R641nm). Rust sources and products in steel girders can be identified by the unique spectral signatures and the rust stains (and thus stain areas) scattered on the coating can be pinpointed at pixel level by the corrosion rust indicators. The chemical integrity of a topcoat is demonstrated by the short-wave infrared spectroscopy and the topcoat degradation can be evaluated by the absorption at 8000 cm-1 and 5850 cm-1.

This work communicates analysis of aluminum monoxide, AlO, laser-plasma emission records using line strength data and the ExoMol astrophysical database. A nonlinear fitting program computes comparisons of measured and simulated diatomic molecular spectra. Predicted cyanide spectra of the AlO, ${\rm B}\ ^2\,\Sigma^+ \longrightarrow {\rm X} \ ^2\,\Sigma^+$, $\Delta {\rm v} = 0, \pm 1, \pm 2, + 3$ sequences and progressions compare nicely with 1 nanometer resolution experimental results. The analysis discusses experiment data captured during laser ablation of Al$_2$O$_3$ with 266-nm, 6-mJ pulses. The accuracy of the AlO line strength data is better than one picometer. This work presents as well comparison of the $^{27}$Al$^{16}$O line strength and of ExoMol data for spectral resolutions of 0.1nm and 0.07nm. Accurate AlO databases show a volley of applications in laboratory and astrophysical plasma diagnosis.

The paper focuses on two unconventional magnetic field-based treatment regimes applied to an alloyed steel before applying a thermochemical treatment. This study was conducted in order to improve the behavior of the chosen material during the wear process. Increasing the wear resistance and the micro-hardness of the superficial layer obtained from the treatments are a priority, as well as improving the mechanical properties of a Cr-Mo alloyed steel. Thermomagnetic treatment, applied before plasma nitriding treatment, improves the mechanical properties of the base material, especially in the case of a steel with a considerable chromium content (1,02%). This paper is a review of my own researches in the last years.

To obtain a given structure in 3D building-up modes, it is necessary to use optimal surfacing modes that determine the amount of heat input in local areas. For this purpose, aluminum bronze was surfacing onto a deformed base and the structure and its characteristics in the surfacing and heat-affected zones were studied by the EBSD method. The heterogeneity of the formation of the structure in each selected zone is established, which indicates the heterogeneity of heat input in local areas of the material in one mode of surfacing. For typical cases of crystallization, a molecular dynamics simulation of crystallization processes with different heat input to the base with characteristics specified based on experimental data was carried out. It has been established that the amount of heat input determines the degree of melting and the inherited defectiveness of growing crystals. The formation of misorientation boundaries and crystallization centers of new grains is determined by the conditions of joint growth of grains with given crystallographic parameters of the computational model. Numerical calculations agree with the experimentally observed results.

The analysis of high-temperature physicochemical properties of theK₃AlF₆-Na₃AlF₆-AlF₃ molten salt system is crucial for practical production of electrolytic aluminum. In this paper, the physicochemical properties of the K₃AlF₆-Na₃AlF₆-AlF₃ molten salt electrolyte system at 1173 K and standard atmospheric pressure were simulated using molecular dynamics calculations. The effects of Zr、B、C、W、Ti、Hf、Nb、and Ta on the radial distribution function, coordination number, viscosity and conductivity of the electrolyte system are discussed in detail. The simulation results show that the coordination number between Al-F and the conductivity is decreasing as the content of B²- increases. And the coordination number between Al-F and the viscosity is decreasing as the content of Zr⁴⁺ increases. With the addition of impurity elements such as C, W, Ti, Hf, Nb, and Ta, the data show that C has no significant effect on this electrolyte system, while the presence of W will decrease the coordination number between Al-F in the system. The presence of Ti, Hf, Nb, and Ta may intensify the decomposition reaction between one of the Al-F ligands, which increases the coordination number between Al-F and the number of ions in the electrolyte. This work provides theoretical support for the subsequent study of inert anodes containing Zr, B, Ti, Hf, Nb, and Ta.

Super duplex stainless steel (SDSS) is used for manufacturing large valves and pipes in offshore plants because of its excellent strength and corrosion resistance. Large valves and pipes are manufactured by forging after casting, and the outside and inside microstructures are different owing to the difference in the cooling rate caused by the thermal conductivity. This microstructural variation causes cracks during solution annealing, which breaks the materials. To study toe corrosion resistance of the SDSS forged material, the microstructure was conducted based on the difference in the cooling rate between the inside and outside of the cast SDSS. To analyze the effects of the secondary phase fraction before solution annealing on the solution and corrosion resistance, the corrosion resistance with and without solution annealing was measured using the potentiodynamic polarization test and critical temperature test after the precipitation of the secondary phase. In the potentiodynamic polarization test, the secondary phase decreased the activation polarization and increased the corrosion rate. The critical pitting temperature exhibited the effect of the secondary phase.

The shield tunnels inevitably endure various damage with the service time increasing. Meanwhile, steel corrugated plate has been used extensively in multiple conditions and proved effective to strengthen the segmental joints by full-scale tests. A numerical model is proposed to probe the feasibility of using new Stainless Steel Corrugated Plate (SSCP) to reinforce the shield tunnel segments. A new method, called virtual tracking element technology, is employed to achieve the simulation of realistic stress state of the segmental joint. Moreover, the segmental joint component analysis and parametric study are conducted based on the numerical model. The results demonstrate that: (1) the virtual tracking element technology proves valid and efficient to simulate the secondary stress state of segmental joint; (2) SSCP reinforcement is not fully utilized when the grade of segmental concrete is C50 and it has abundant safety margin for potential overload; (3) SSCP reinforcement is well-performed regardless of the burial depth and reinforcement in advance is recommended.

This study utilized electron back scattered diffraction (EBSD) and X-ray diffraction (XRD) to investigate the impact of inter-annealing temperature and heating rate of final annealing on the microstructure of high-voltage anode aluminum foils. The findings indicate that the formation of cube texture in the final products is significantly influenced by the inter-annealing temperature, as low inter-annealing temperatures retain a considerable amount of deformation stored energy, providing a strong driving force for nucleation. The cube texture is observed to deviate from the ideal position at lower inter-annealing temperatures. Additionally, an increase in heating rate during final annealing leads to a gradual decrease in the fraction and grain size of recrystallization. This is attributed to the fact that a higher heating rate (below the critical heating rate) reduces the time available for grain boundary migration, thereby slowing the recrystallization process.

This research is aimed to develop the method for damage degree evaluation in metals and alloys during their deformation and destruction based on acoustic emission (AE) technique. Experimental studies were carried out on tensile specimens of high-strength steel with simultaneous registration of AE signals in tested material. It was shown that the time-dependent AE primary parameters, such as the AE signal maximum amplitudes and AE activity, do not have a clear relationship with the material damage degree. This fact makes it difficult to use standard methods for assessing the damage degree of acoustic signal sources, including defects. It was proposed to use the Kolmogorov-Smirnov criterion to differ the processes of metal plastic deformation and crack propagation during the rupture. The possibility of estimating the material damage degree by high-energy AE hits share was shown. Besides, a particular expression was obtained for evaluating the damage degree for the material under study.

Aiming to diminish the defects caused by high-speed pulsed GMAW welding, such as non-penetration, non-fusion, humping and undercut, the paper proposed an improved twin-wire double-pulsed high-speed welding process by introducing the impact of additional shielding gas on the welding pool and the effects of different shielding gas flowrates on the microstructure and mechanical properties of the welded seam was investigated. The 2205 duplex stainless steel plate was used as the base material for the butt welding test, and the welded seams were subjected to tensile test, metallographic analysis, hardness analysis, and nondestructive testing. The results indicate that as the flowrate of additional shielding gas increases in the range of 8 L/min~16 L/min, the width of the welded seam increases and the height of reinforcement decreases gradually. However, a grooved seam with a lower middle region and higher sides will appear when the gas flowrate becomes excessively large. The test results indicate that the jet impact force is relatively moderate when the flowrate of the additional shielding gas is 12 L/min and thus, is optimal for the welded seam.

Features of nanosecond discharge development in a non-uniform electric field are studied experimentally. High spatial resolution imaging showed that thin luminous tracks of great length with a cross-section of a few microns are observed against the background of discharge glow in air and argon. It has been established that the detected tracks are adjacent to brightly luminous white spots on the electrodes or to the vicinity of these spots, and are associated with the flight of small particles. It is shown that the traces have various shapes and change from pulse to pulse. The particle tracks may look like curvy or straight lines. In some photos, they can change the direction of movement to the opposite. The particle trace was found to abruptly cut off and a bright flash is visible at the trail break point. The color of the tracks differs from that of the spark leaders, while the bands of the second positive nitrogen system dominate in the gap spectra during the existence of a diffuse discharge. Areas of blue light are evident near the electrodes, as well. Development of glow in the gap during its breakdown is revealed using an ICCD camera. Physical reasons for the observed phenomena are discussed.

Epoxy was blended with benzoxazine resin and aluminum trihydrate (ATH) additive to render flame retardancy while maintaining mechanical properties. The ATH was modified using three different silane coupling agents and then added to 60/40 epoxy/benzoxazine mixtures. The effect of blend compositions and surface modification on flame retardant and mechanical properties of the composites was investigated by UL94, tensile, and shear tests. Resin mixtures containing more than 40 wt% benzoxazine revealed a UL94 V-1 rating with enhanced tensile and shear strength. Upon addition of 20 wt% ATH to 60/40 epoxy/benzoxazine, a V-0 rating was achieved. The lowered tensile and adhesive properties of the composites in the presence of ATH were improved by modifying the ATH surface using silane coupling agents.

This paper analyzed the main diseases of the friction high-strength bolt (FHSB) joints in order to study the characteristics of the corrosion products of the joints in steel bridge and the influence factors. Seven representative FHSB connection pairs and eight steel plate samples were selected from the Dongying Shengli Yellow River Bridge, which has been in operation for 33 years. Then Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS) and X-Ray Diffraction (XRD) were used to analyze the microscopic morphology and chemical composition of the corroded surface of the samples. Finally, this paper discussed the relationship between the corroded sample surface and the environmental corrosion. The research results showed that construction quality problems, such as non-standard hole expansion, segmental slab joint dislocation and contact surface pollution, accelerated corrosion of the contact surface. With the increase of corrosion degree of joints, the contact surface of aluminum spraying layer gradually changed from a rugged and dense state to a smooth and porous powder state. With the corrosion of the steel plate substrate, the contact surface gradually changed from a fluffy stratified state to a surface bonding state. It was inferred that the friction coefficient of the FHSB connection node on the corroded aluminum sprayed contact surface first decreased and then increased. The corroded node samples detected not only a large number of S and Cl elements, but also the oxides of Mn, Si and other elements as well as FeS. It was speculated that node corrosion was also related to atmospheric (acid rain) and industrial dust and other corrosive environments. Almost all samples detected the component SiO2 of the Yellow River soil, as well as Mg, Ca, K, Na and other elements at the same time, which is basically consistent with the component elements of the Yellow River soil. Therefore, it was inferred that it was related to the inclusion of the Yellow River soil.

The present work aims to explain the aluminum hydrolysis reaction kinetics based on properly chosen theoretical model with machined aluminum waste chips and alkali solutions up to 1M as a promoter, and to estimate overall reaction profit. In order to obtain results of better accuracy, we work with flat Al waste chips because a flat surface is preferable to maximally increase the time for created hydrogen bubbles to reach the critical gas pressure. At describing the reaction kinetics, flat shape allows using a planar one-dimensional shrinking core model instead of much complicated polydisperse spheric shrinking core model. We analyze the surface chemical reaction and mass transfer rate steps to obtain the first order rate constant for surface reaction and the diffusion coefficient of aqueous reactant in the byproduct layer, respectively. With our reactor we achieved H2 yield of 1145 mL per 1 g Al with 1M NaOH, which is 92% of the theoretical maximum. At estimation of the profit, we pay much attention to the loss of alkaline and find a crucial dependence on its price. Nevertheless, in terms of consumed and originated materials for sale, conversion of the aluminum waste material into green hydrogen by properly chosen reaction parameters has a positive profit even by consuming alkali of chemical grade.

The accumulation of steel slag and other industrial solid wastes has caused serious environmental pollution and resource waste. The resource utilization of steel slag is imminent. In this paper, alkali activated materials ultra-high performance concrete (AAM-UHPC) was prepared by replacing GGBFS powder with different proportions of steel slag powder, and its workability, mechanical properties, curing condition, microstructure, and pore structure were investigated. The results illustrate that the incorporation of steel slag powder can significantly delay the setting time and improve the flowability of AAM-UHPC, making it possible for engineering applications. The mechanical properties of AAM-UHPC showed a tendency to increase and then decrease with the increase of steel slag dosing, and reached the best performance at 30% dosage of steel slag. The maximum compressive strength and flexural strength are 157.1 MPa and 16.32 MPa, respectively. High temperature steam or hot water curing at early age was beneficial to the strength development of AAM-UHPC, but continuous high temperature hot and humid curing would lead to strength inversion. When the dosage of steel slag is 30%, the average pore diameter of the matrix is only 8.43nm, and the appropriate steel slag dosage can reduce the heat of hydration and refine the pore size distribution, making the matrix more dense.

Immobilized metal affinity chromatography (IMAC) is a popular and valuable method for the affinity purification of polyhistidine-tagged recombinant proteins. However, it often shows practical limitations, which might require cumbersome optimizations, additional polishing, and enrichment steps. Here, we present functionalized corundum particles for the efficient, economical, and fast purification of recombinant proteins in a column-free format. The corundum surface is first derivatized with the amino silane APTES, then EDTA dianhydride, and subsequently loaded with nickel ions. The Kaiser test, well-known in solid-phase peptide synthesis, was used to monitor amino silanization and the reaction with EDTA dianhydride. In addition, ICP-MS was performed to quantify the metal-binding capacity. His-tagged protein A/G (PAG), mixed with bovine serum albumin (BSA), was used as a test system. The PAG binding capacity was around 3 mg protein per gram of corundum. Cytoplasm obtained from different E. coli strains was examined as an example of a complex matrix. The imidazole concentration was varied in the loading and washing buffers. As expected, higher imidazole concentrations during loading are usually beneficial when higher purities are desired. Even when higher sample volumes, such as one liter, were used, recombinant protein down to a concentration of 1 µg/mL could be isolated selectively. Comparing the corundum material with standard Ni-NTA agarose beads indicated higher purities of proteins isolated using corundum. His6-MBP-mSA2, a fusion protein consisting of monomeric streptavidin and maltose-binding protein in the cytoplasm of E. coli, was purified successfully. To show that this method is also suitable for mammalian cell culture supernatants, purification of the SARS-CoV-2-S-RBD His8 expressed in human Expi293F cells was performed. The material cost of the nickel-loaded corundum material (without regeneration) is estimated to be less than 30 cents for 1 gram of functionalized support or 10 cents per milligram of isolated protein. Another advantage of the novel system is the corundum particles' extremely high physical and chemical stability. The new material should be applicable in small laboratories and large-scale industrial applications. In summary, we could show that this new material is an efficient, robust, and cost-effective purification platform for the purification of His-tagged proteins, even in challenging, complex matrices and large sample volumes of low product concentration.

Near-neutral pH and low redox potentials (EH) are considered favorable conditions for radionuclides immobilization in deep repository systems in clay geological formations. Cigeo is a future Industrial Centre for Geological Disposal for Nuclear Waste (NW) for high-level and intermediate level long-lived radioactive waste, to be built in France, at 500 m depth within the Callovo-Oxfordian clay formation. Deep knowledge of the mechanisms and kinetics of corrosion occurring at the external surface of tubings made of API 5L X65 carbon steel (CS-X65) in contact with COx pore water, is essential for a reversible NW management of the Cigeo site. By using robust handmade electrodes and electrochemical and gravimetric techniques, this work aimed to determine the corrosion phenomenology and kinetics of CS-X65 in contact with COx pore water flowing continuously through a Multi-Parameter Probe (MPP) device, placed at 500 m depth, for more than 180 days. It also aimed at demonstrating the reliability and the robustness of the measurement methodology for the corrosion evaluation of the metallic liner of the future nuclear waste disposal site. Two iron oxidants were encountered, oxygen, who was depleted, and proton, who was accompanied by hydrogen sulfide. Corrosion mechanisms and kinetics were well established for two CS-X65, electrochemically perturbed and not. The corrosion thickness loss rates stand between 0.016 and 0.032 mm/y.

Long-span steel structure trusses are widely used in factory buildings, but with the growth of service time and the increase of dynamic load fatigue, a considerable part of the long-span truss with dynamic load appears serious transverse cracks at the bottom of the middle span and oblique deformation of the abdomen in the operation process. The U-shaped cracks at the bottom and belly, as well as the mid-span down deflection of the main truss, reduced the functional function of the factory building truss structure, and had to limit the original crane load, which affected the normal safety and durability of the structure. Therefore, the application principle of the variable axial force cable system in the long-span factory building truss structure and 3D3S software modeling [1] were used. Analyzing and studying the reinforcement method of large-span powerhouse truss can provide practical experience for subsequent similar projects. In view of the above phenomenon, the large-span powerhouse trusses of Hongcheng Powerhouse 1 and No.2 located in Tonglu, Zhejiang Province are used as the research object, and the variable axial force cable method is proposed to strengthen and lift the load. Considering the span of large-span powerhouse truss, the cable system with 22m controlling force of 400kN is proposed to be selected for powerhouse 1, and the cable system with variable axial force of 24m is proposed to be selected for Powerhouse 2. The force model of large-span truss is established by using the finite element method commonly used to analyze the force of truss. Under two working conditions, The influence of reinforcement effect is analyzed and compared from three aspects: stiffness, bearing capacity and stability. And the phenomenon of uneven stress distribution is analyzed. The stress distribution characteristics of each node are understood by simulating the most disadvantageous node plates with the greatest internal force before and after reinforcement.

This study investigates the effects of the antiperspirant aluminum chlorohydrate on the development of antibiotic resistance in commensal Staphylococcus epidermidis isolates. The isolates were exposed to aluminum chlorohydrate for 30 days, respectively. The bacteria that developed resistance to oxacillin, and ciprofloxacin were isolated, and the expression levels of some antibiotic resistance genes were determined by quantitative reverse transcriptase-PCR. Before and after the exposure, the minimum inhibitory concentration (MIC) values of the bacteria were determined by the microdilution method. A time-dependent increase was observed in the number of bacteria that developed resistance and increased the MIC value. Consistent with the ciprofloxacin resistance observed after exposure, an increase in the norA, norB/C, gyrA, gyrB, parC, and parE gene expressions was observed. In addition to aluminum chlorohydrate exposure, oxacillin resistance was observed in all test bacteria in the group subcultured only in the medium, suggesting that phenotypic resistance cannot be correlated with chemical exposure in the light of these data. The increase in mecA gene expressions of selected test bacteria that acquired resistance to oxacillin after exposure compared with control groups suggests that the observed resistance may be related to aluminum chlorohydrate exposure. To our knowledge, this is the first time in the literature that the effects of aluminum chlorohydrate as an antiperspirant on the development of antibiotic resistance in Staphylococcus epidermidis have been reported.

Background: Aluminum phosphide (AlP), also known as “rice tablet,” is widely used as an effective pesticide. However, AlP poisoning is a common cause of mortality in many countries, such as Iran. Unfortunately, there is no specific antidote for AlP toxicity to date. AlP releases phosphine gas when it is exposed to moisture and acid. Phosphine is a robust mitochondrial toxin that could significantly inhibit cellular energy metabolism. AlP poisoning is an emergency condition that needs instant and effective intervention. Dihydroxyacetone (DHA) is a simple saccharide used for several pharmacological as well as cosmetic purposes. Previously, we found that DHA could significantly prevent mitochondrial impairment induced by toxic agents such as cyanide and phosphine in various in vitro and in vivo experimental models.Methods: Hospitalized patients (n = 111) were evaluated for eligibility criteria. Among these patients, n = 35 cases were excluded due to incomplete data (n = 11) and suspicion of poisoning rather than AlP (n = 24). Meanwhile, n = 76 cases with confirmed AlP poisoning were included in the study. AlP-poisoned patients who did not receive DHA (n =18) were used as the control group.Patients (n = 58) received at least one dose of DHA (500 ml of 5% DHA solution w/v, i.v.) in addition to routine treatment of AlP poisoning. Arterial blood gas (ABG), blood pH, bicarbonate levels, and other vital signs and biochemical measurements were monitored. Moreover, the mortality rate and time of hospitalization were evaluated in both DHA-treated (n = 58) and AlP-poisoned patients without DHA administration (n = 18). Several biomarkers were assessed before (upon hospitalization) and after DHA treatment. The routine tests for AlP-poisoned patients in this study were the measurement of electrolytes (K+ and Na+), WBC, RBC, hemoglobin, INR, carbonate (HCO3), blood pH, PaCO2, and PaO2 and SGPT, SGOT, BUN, Cr. Results: Upon patients' admission, significant decreases in blood pH (acidosis), blood PaO₂, and HCO₃ levels were the hallmarks of AlP poisoning. It was found that DHA significantly alleviated biomarkers of AlP poisoning and tremendously enhanced patients’ survival rate compared to patients treated based on hospital routine AlP poisoning protocols (no DHA). No significant adverse effects were evident in DHA-treated patients in the current study.Interpretation: These data suggest that parenteral DHA is a novel and effective antidote against AlP poisoning.Trial registration: IR.SUMS.REC.1394.102

The literature has well established prestressing in concrete beams and its calculation procedures. However, its use in composite steel-concrete beams has increased despite main normative codes lacking a specific approach for it. Designers must, in most cases, combine the available criteria to calculate the standards of steel and reinforced concrete structures. This study aimed to formulate this optimization problem and analyze CO2 emissions for the optimal design of composite steel-concrete beams with external prestressing. The design variables for the optimization problem include cross-section of laminated or welded profiles, slab height, characteristic strength of concrete to compression, and number of tendons. We obtained a solution for the optimization problem via a genetic algorithm (GA) and a particle swarm optimization one (PSO). Comparative analysis with experimental example and with optimization problem of prestressed steel beam are performed. An parametric analysis to several spams is performed, which enabled to evaluate the factors that most impact CO2 emissions. According to results, the chosen algorithms effectively obtained solutions for the problem, and PSO usually provided better results than GA. Regarding the final solution composition, steel contributes the most to emissions, welded profiles provided better solutions than laminated ones, and laminated spans of up to 17.5m and welded ones up to 27.5m dispensed with tendons.

This article reports on the comparative study of the hot deformation behaviour of virgin (steel A) and rejuvenated heat treatment creep-exhausted (steel B) P91 steels. Hot uniaxial compression tests were conducted on the two steels at the deformation temperature range of 900°C-1050°C and a strain rate range of 0.01-10s-1 to 0.6 strain using Gleeble® 3500 equipment. The results showed that the flow stress largely depends on the deformation conditions. The flow stress for the two steels increased with an increase in strain rate at a given deformation temperature and vice versa. The flow stress-strain curves exhibited a dynamic recovery as the softening mechanism. The material constants determined using Arrhenius constitutive equations were: stress exponent was: steel A (5.76) and steel B (6.67), and the apparent activation energy was: steel A (473.1 kJ mol-1) and steel B (564.5 kJmol-1). From these results, steel A exhibited better workability than steel B. Statistical parameters analyses showed that the flow stress for the two steels had a good correlation between the experimental and predicted data. Pearson’s correlation coefficient (R) was: steel A (0.97) and steel B (0.98). The Average Absolute Relative Error (AARE) values were: 7.62% (steel A) and 6.54% (steel B). The study shows that the Arrhenius equations can effectively describe the flow stress behaviour of P91 steel, and this method is applicable to the industrial metalworking process.

In this paper, in order to provide proper parameters for the preparation of semi-solid billets, the semi-solid annealing of hot-rolled 2A14 Al alloy was investigated. The microstructure was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) with X-ray energy dispersive spectrometer (EDS) and electron backscattered diffraction (EBSD), scanning transmission electron microscope (STEM). XRD results show that with the increase of temperature, equilibrium θ-Al2Cu gradually dissolved in the matrix. The EDS results of SEM and STEM show that there were coarse θ-Al2Cu phase, ultra-fine precipitate Al(MnFeSi) or (Mn, Fe)Al6 phase and atomic clusters in the microstructure. EBSD results show that the recrystallization mechanism was dominated by continuous static recrystallization (CSRX), the homogeneous nucleation occurred when the sample was heated to near solidus temperature, and CSRX happened in the semi-solid temperature. In the process of recrystallization, the micro-texture changed from preferred orientation to random orientation. A variety of experimental results show that static recrystallization (SRX) occurred at semi-solid temperature due to the blocking effect of atomic clusters on dislocation slip and the Zener drag effect of fine precipitates on low angle grain boundaries (LAGBs) disappeared with melting at semi-solid temperature.

: The paper presents the results of uniaxial tensile tests of samples of hypoeutectic aluminum-silicon alloy A319. According to the results of which the influence of surface treatment by a pulsed electron beam on the mechanical properties of the material was determined. The peculiarities of localization of deformation in the material, caused by grinding of the surface layer material structure due to rapid crystallization during electron beam treatment were revealed. The surface treatment up to 100 µm depth leads to the formation of a fine dendritic columnar structure of silumin and to an increase in the plasticity of the samples. The influence of surface treatment affects the increase of deformation localization in the region of stable concentrator before failure. The largest increase in ductility and localization of deformation occurs during processing with energy density of 15 J/cm2. In the process of specimen deformation, unstable, metastable, and stable areas of plastic deformation localization are formed and replaced, and the formation of stable areas of localized plastic deformation, in which the specimen fails at the end of the test, can be detected at the initial stages of testing. In specimens, during testing in the zone of localized plastic deformation, bands are formed that pass through the entire surface of the specimen at an angle from 35 to 55 degrees to the axis of tension, their evolution leads to the formation of stable zones of localized plastic deformation and to the failure of the specimen.

Cold gas dynamic spray (CS) is a unique technique to deposit material using high strain rate solid state deformation. A major challenge for this technique is its dependence on the powder properties and lack of standards to assess them between lots and manufacturers. The motivation of this research was to understand the variability in powder atomization techniques for stainless steel powders and their subsequent properties for their corresponding impact on CS. A drastic difference (~30%) was observed in deposition efficiencies (DE) of unaltered, spherical, and similar sized stainless steel (316) powders produced using centrifugal (C.A) and traditional gas atomization (G.A) techniques. The study highlights more on differences on precursor level. Using recent advancements in large scale statistical measurements like laser diffraction shape analysis, µCT scanning, traditional methods like EBSD, nano-indentation, an attempt is made to understand the powder property. Insights on powder size and shape are documented. Significant differences were observed between C.A and G.A powders in terms of grain size, fraction of higher angle grain boundaries (HAGB) and nano hardness. The outcomes of this study would be helpful to understand the commercialization of the cold-spray process for bulk manufacturing of powder precursors

A steel damper column is an energy-dissipating member that is suitable for reinforced concrete (RC) buildings and multistory housing. To assess the seismic performance of buildings with steel damper columns, the peak displacement of the whole building and the energy dissipation demand of the dampers must be evaluated. This article proposes an energy-based prediction procedure for the peak and cumulative response of an RC frame building with steel damper columns. The proposed procedure considers two energy-related seismic intensity parameters, namely the maximum momentary input energy and the total input energy. The peak displacement is predicted considering the energy balance during a half cycle of the structural response, using the maximum momentary input energy. The energy dissipation demand of the dampers is then predicted considering the energy balance during a whole response cycle using the total input energy. The local responses (e.g., peak drift, maximum plastic rotation of beams, maximum shear strain, and energy dissipation demand of dampers) are predicted using pushover analysis. Numerical analysis results for 8- and 16-story RC buildings show that the proposed prediction method achieves satisfactory accuracy.

To provide carbon steel a long corrosion protection effect in NaCl solution with various pH, a pH-controlled intelligent inhibitor based on poly-acrylamide (PAM) and oleate imidazoline (OIM) was synthesized. SEM, FT-IR and TGA results indicating the OIM inhibitor was successfully loaded into PAM hydrogel with a very high content (39.64 wt%). The OIM release behavior from hydrogel structure have two stages, quickly release and sustained release. The pH of solution could affect the initial release kinetics of OIM inhibitor and the diffusion path in hydrogel structure. Weight loss measurement of L80 steel in different pH solution with OIM@PAM proved the inhibitor responsive release mechanism and an-ti-corrosion performance. The inhibition efficiency of OIM@PAM can maintain over 80% after long term immersion in harsh corrosive environment (pH 3), which is much higher than the inhibition efficiency of inhibitor in moderate corrosive solution.

The conductor aluminum alloys Al-0.25wt.%Zr doped additionally with Х = Er, Si, Hf, and Nb were the objects of investigations. The fine-grained microstructure in the alloys was formed by Equal Channel Angular Pressing and Rotary Swaging. The thermal stability of the microstructure, specific electrical resistivity, and microhardness of the novel conductor aluminum alloys was investigated. The mechanisms of nucleation of the Al3(Zr,X) secondary particles during annealing the fine-grained aluminum alloys were determined using Jones-Mehl-Avrami-Kolmogorov equation. Using Zener equation, the dependencies of the mean secondary particle sizes on the annealing time were obtained on the base of analysis of the data on the grain growth in the aluminum alloys. The secondary particle nucleation during long-time low-temperature annealing (300 оC, 1000 hrs) was shown to go preferentially at the cores of the lattice dislocations. The Al-0.25%Zr-0.25%Er-0.20%Hf-0.15%Si alloy subjected to long-time annealing at 300 оC has the optimal combination of the microhardness and electrical conductivity (59.8%IACS, Hv = 480 ± 15 MPa).

The research was undertaken to study the way deformation behaves in ultrafine-grained (UFG) conducting Al-Zr alloys doped with Sc, Hf, and Yb. All in all, 8 alloys were studied with zirconium partially replaced by Sc, Hf, and/or Yb. Doping elements (X = Zr, Sc, Hf, Yb) in the alloys total 0.4 wt.%. The choice of doping elements is conditioned by possible precipitation of Al3X particles with L12 structure while annealing these alloys. Such particles provide higher thermal stability of a nonequilibrium UFG microstructure. Initial coarse-grained samples were obtained by induction casting. The UFG microstructure in the alloys was formed by Equal Channel Angular Pressing (ECAP) at 225°C. Superplasticity tests were carried out at temperatures ranging from 300 to 500 °C and strain rates varying between 3.310-4 and 3.310-1 s-1. The highest values of elongation to failure are observed in Sc-doped alloys. A UFG Al-0.2%Zr-0.1%Sc-0.1%Hf alloy has maximum ductility: at 450 °C and a strain rate of 3.310-3 s-1, relative elongation to failure reaches 765%. At the onset of superplasticity, stress–strain curves are characterized by a stage of homogeneous strain and a long stage of localized plastic flow. The dependence of homogeneous strain (eq) on test temperature in UFG Sc-doped alloys is increasing uniformly, which is not the case for other UFG alloys with eq(T) dependence peaking at 350-400 оС. Strain rate sensitivity coefficient of flow stress m is small and does not exceed 0.26-0.3 at 400-500 °C. In UFG alloys containing no scandium, m coefficient is observed to go down to 0.12-0.18 at 500 оС. It has been suggested that lower m values are driven by intensive grain growth and pore formation in large Al3X particles, which develop specifically at the ingot crystallization stage.

Al-6%Mg-Sc-Zr alloys with the total ratio of Sc + Zr = 0.32 wt.% make up the target of this research. The content of scandium and zirconium varied with an increment of 0.02%. The alloys were produced by induction casting. Their ultrafine-grained (UFG) microstructure was formed with Equal Channel Angular Pressing (ECAP). Such cast alloys have a homogeneous macrostructure formed by small equiaxed grains in the central part of the ingot and columnar crystals along the edges of the cross section. After ECAP, the average grain size in the alloy specimens is 0.5–1 µm. The average grain size does not depend on the ratio of Sc and Zr in these alloys. Superplasticity tests were performed at temperatures ranging from 300 to 500 °C and at a strain rate varying between 3.3·10-3 and 3.3·10-1 s-1. UFG Al-6%Mg-0.20%Sc-0.12%Zr and Al-6%Mg-0.18%Sc-0.14%Zr alloys exhibit the highest superplasticity. It was suggested that changes in Sc:Zr ratio affect spatial distribution and composition of the following precipitating particles: Al3Sc, Al3Zr, Al3(ScxZr1-x). An increase in Zr concentration is shown to reduce the susceptibility of UFG alloys to cavitation fracture.

In the field of metallurgy, there are many factors that influence the final quality of cast iron. These are mainly charge materials, chemical composition, metallurgical preparation up to the final casting process. Even small deviations from metallurgical processing lead to fluctuations in melt quality and the occurrence of casting defects. Charge materials has a significant impact on the quality of cast iron, especially steel scrap, which is increasingly used from an economic and ecological point of view, especially when melting cast iron in electric furnaces. Cast iron produced from a higher proportion of steel scrap in the charge has higher hardness and tensile strength. On the other side, these cast irons has a higher tendency to chillout, brittleness, shrinkage, pearlitic microstructure, stresses and higher purity due to the difference in hardness at different wall thicknesses of the castings. It is the high hardness that is the problem in the final machining of castings. These negative properties are recorded mainly in heavy thick-walled castings with higher tensile strength and hardness. This negative effect is mainly due to the nitrogen content in the steel scrap. Based on these knowledges, operating melts were realized in the foundry's operating conditions. The influence of steel scrap in the charge and the possibility of eliminating its negative effects on the properties of cast iron were investigated.

This study employs a high-fidelity numerical framework to determine the plastic material flow patterns and temperature distributions that lead to void formation during friction stir welding (FSW), and to relate the void morphologies to the underlying alloy material properties and process conditions. Three aluminum alloys, viz., 6061-T6, 7075-T6, and 5053-H18 were investigated under varying traverse speeds. The choice of aluminum alloys enables investigation of a wide range of thermal and mechanical properties. The numerical simulations were validated using experimental observations of void morphologies in these three alloys. Temperatures, plastic strain rates, and material flow patterns are considered. The key results from this study are: (1) The predicted stir zone and void morphology are in good agreement with the experimental observations, (2) The temperature and plastic strain-rate maps in the steady-state process conditions show a strong dependency on the alloy type and traverse speeds, (3) The material velocity contours provide a good insight into the material flow in the stir zone for the FSW process conditions that result in voids as well as those that do not result in voids. The numerical model and the ensuing parametric studies presented in this work provide a framework for understanding material flow under different process conditions in aluminum alloys, and potentially in other alloys. Furthermore, the utility of the numerical model for making quantitative predictions and investigating different process parameters to reduce void formation is demonstrated.

The results of the study of the influence of the size of cylindrical samples of A5N aluminum on the time and rate of their cooling are presented. According to experimental data, the temperature dependence of the heat transfer coefficient for pure metals is calculated. It revealed that the process of cooling of the aluminium and its alloys has a relaxation behavior. It has found that the main mechanisms of natural air cooling are convection heat transfer and radiation. The characteristic cooling time due to radiation is less than due to convection. The contribution of thermal radiation is noticeable at high temperatures. It was found that the characteristic times of cooling due to radiation and convection increase with increase in volume to area ratio of the sample.

CO₂ emissions have been identified as the main driver for climate change, with devastating consequences for the global natural environment. The steel industry is responsible for ca. 8%-11% of global CO₂ emissions, due to high fossil-fuel and energy consumption. The onus is therefore on industry to remedy the environmental damage caused and to decarbonise production. This desk research report follows a two-tiered route: 1) exploring the Bio Steel Cycle; 2) proposing a seven-step strategy to overcome the challenges within the iron and steel industry. The true levels of CO₂ emissions in the steelmaking process, during the blast-furnace/basic-oxygen-furnace operation, will be detailed first, at 4.61t of CO₂ emissions/t of steel produced. The manuscript proposes a solution for reduced carbon emissions steelmaking with the Bio Steel Cycle components and detail on how to reach net-zero carbon emissions steel production. The 7-step-implementation-strategy as a potential solution to achieve net and true zero carbon emissions steel production in the short to medium-term. The findings of this are pointing towards the conclusion that CO₂ emissions seem to have been under-reported and under-estimated in the past, but the emission can be addressed if the correct scenarios for net-zero steel manufacturing are implemented by 2050.

The solid-state welding method known as friction stir welding (FSW) bonds two metallic work parts, whether the same or different, by plastically deforming the base metal. The frictional resistance between both metallic work pieces causes them to produce heat, which produces plastic deformation and welds them. However, the weldability and strength of FSW joints mainly depend on the FSW parameters. This review work highlights the previous research work on the FSW parameters and their effects on the weldability and quality of the aluminum alloys joined with similar and dissimilar metals through the FSW method. About 150 research studies were systematically reviewed, and the articles included data from peer-reviewed journals. It has been concluded that the key parameters, including welding speed, “rotational speed”, “plunge depth”, “spindle torque”, “shoulder design”, “base material”, “pin profile” and “tool type", significantly affect the weldability of the aluminum joint through the FSW method. Also, the selection of these parameters is important and fundamental as they directly affect the joint. It is recommended that future work focus on FSW for aluminum. Among these, the most essential is the application of artificial intelligence (AI) techniques to select the optimum FSW parameters for aluminum welding.

Steel slag is a co-product of the steelmaking industry, this material is rarely used as a binder due to its low cementitious properties. Thus, it´s believed that the alkaline activation of steel slag can enable its use as a cementitious material. This work has the objective of making a systematic bibliographic review on the theme "slag melt as a precursor in activated alkali binders". To this end, the ProKnow-C method was used for the selection and analysis of relevant research on the topic. The portfolio resulted in 71 texts, mostly journals paper. Bibliometrics showed that the country with the most publications is China and the journal with the most publications is Construction and Building Materials. The critical analysis concluded that the XRD, XRF, and compressive strength tests are the most used for the characterization of the material. It is possible to establish that there are some knowledge gaps on the subject, such as better mechanical characterization and greater production of works with dosing by the one-part method.

Magnesium and Aluminum alloys continue to be important in the context of modern and lightweight technologies. With the advancement of additive manufacturing (AM), components can be produced directly in a net shape, widen up the usage of magnesium and aluminum alloys as well as holding new ideas for the application of unique physical structures made feasible by 3D printing. Laser-based approach, one of the metal additive manufacturing (AM) methods, enables the formation of arbitrary 3D structures. With promising findings, research in this area is advancing quickly, bringing up a variety of potential applications in both the scientific and industrial sectors. Complex structures can now be manufactured easily utilizing AM technologies to meet the pre-requisite objectives like reduced part numbers, greater functionality, and lightweight, among others. AM has the ability to meet demands by lowering costs and speeding up the manufacturing process. Due to their popularity in numerous high-value applications, aluminum, and magnesium alloys are one of the key material systems being researched in the laser-based additive manufacturing approaches. The review here aims to comprehensively examine the additive manufacturing of magnesium and aluminum alloys, highlighting the influence of the laser-based additive manufacturing approach on the mechanical characteristics, microstructure, and tribological performance of magnesium and aluminum alloys.

Atmospheric corrosion of aluminum aircraft structures occurs due to numerous reasons. A typical phenomenon leading to corrosion is the deliquescence of contaminants such as salts due to changes in relative humidity (RH) caused by aircraft operation at different altitudes and climate zones. Currently, corrosion of aircrafts is controlled by scheduled inspections. In contrast, the present contribution aims for a continuous monitoring approach by using the acoustic emission (AE) method to detect and further evaluate atmospheric corrosion. The AE method is frequently used for corrosion detection at typically immersion-like conditions or for corrosion types where stress-induced cracking is involved. However, it has not yet been demonstrated for atmospheric corrosion at unloaded aluminum structures. To address this question, the present investigation uses small droplets of a corrosive sodium chloride (NaCl) solution to induce atmospheric corrosion on aluminum alloy AA2024-T351. Operating conditions of an aircraft are simulated by a controlled variation in RH. In addition, videos of the corrosion site are recorded to visually observe the corrosion process. Pitting corrosion is generated and clearly measurable AE signals are detected. An automatic video processing algorithm looking for sudden changes on the corrosion site mainly detects hydrogen bubbles formed when aluminum reacts with aqueous solutions. A clear correlation between the observed pitting corrosion, the AE and the hydrogen bubble activity and the RH, i.e., the electrolyte present at the aluminum surface, is found. Thus, the findings demonstrate the applicability of the AE method for monitoring atmospheric corrosion of aluminum aircraft structures by today’s measurement equipment. Numerous potential effects that can cause measurable AE signals are investigated and discussed. Among these, bubble activity is clearly considered to be the most emissive one.

The current study aimed to evaluate the influence of different sintering temperatures on the properties of copper aluminum oxide (CuAlO₂) pellets synthesized from copper oxide (CuO) and aluminum hydroxide (Al(OH)₃) for application in smart infrastructure systems. The pellets were sintered at 400 K, 1000 K, and 1300 K, in the presence of nitrogen gas flow to reduce the amount of oxygen availability. The CuAlO₂ sintered nanoparticles were chemically analyzed by X-ray diffractometry, and the nanostructure of the materials was studied by scanning electron microscopy. The transmittance of the sintered materials was examined by ultraviolet/visible (UV/Vis) spectrophotometry, and 88% transparency was observed for the pellets sintered at 1300 K. Electrical conductivity was measured at 0.905 mS/cm, indicating a semiconducting behavior.

Steel fibres provides ductility to concrete structures. This in turn gives possibility to replace or reduce conventional reinforcement in structural elements. In this study the focus is on structural walls and the fibres as potential replacement for horizontal reinforcement in areas where vertical re-bars are needed. An experimental study was conducted, in which prismatic specimens with longitudinal re-bars were subjected to centric loading. Ten samples with 12 specimens in each were tested. The parameters considered were: fibre content, concrete cover for the longitudinal bars, and presence of stirrups. Self-compacting concrete with 30 and 60 kg/m3 steel fibres was used. The influence of fibres on maximum load, stiffness, and ductility of the specimens is evaluated. The results show that fibres eliminated brittle collapse and spalling of concrete at failure. Samples with fibres tend to have reduced maximum force and stiffness but increased ductility. The specimens with fibre content of 60 kg/m3 showed more ductile behaviour than the ones with minimum amount of conventional stirrups. The study suggests that combination of steel fibres and conventional re-bars can lead to less qualitative compactness of the self-compacting concrete, which in turn may reduce load bearing capacity and stiffness of the structure.

This study is follow-up of the steel shot transformation under the influence of environmental factors research (Lisin et al., 2022) and is the initial stage of investigating the iron behavior in soils during steel shot corrosion under a number of factors: the metallic lead in soils, atmospheric precipitation, excess organic matter. The results obtained show that corrosion of steel ammunition is a continuous process, including the formation of a poorly soluble rust crust on the surface of the steel and the mineralization of the metal until it is destroyed. As a result, the metal transformed into rust form, is a constant source of iron ions and dispersed rust particles migrating in soil waters and accumulating in soils. In addition, the aggregation of corrosion products of steel ammunition is the cause of a change in physical and mechanical properties of soils, which leads to a violation of the air and water migration regime of soils and an increase in surface runoff from the territories of shooting activity. The highest environmental risks are observed when steel ammunition is used on shooting areas where metallic lead intensifies steel shot corrosion rate, while the deposited steel shot activates the deterioration of previously encapsulated metal and — if steel and lead ammunition are used at the same time — slows down the encapsulation of newly deposited metallic lead, which catalyses the accumulation and migration of lead in environmental components.

Despite significant advances in metallurgy and the potential to create high and very high-strength steel, all international specifications for steel design provided little information about the limits of slenderness for high-strength steel sections (HSSs) and didn’t give anything about the design of very high-strength steel sections (VHSSs). The American structural steel design specification covers circular hollow sections (CHS) of steel grades up to S690, while it isn't in ANSI/AISC 360-16 and ASTM A514/A514M. Euro code EN 1993-1-1 can be applicable only to steel grades up to S460. EN 1993-1-3 and EN 1993-1-12 contain supplementary rules for cold-formed members and HSS (S460- S700), respectively. Though ductility requirements for (HSS) are specifically established in EN 1993-1-12, it is largely a continuation of the normal-strength-steel design procedures standardized in EN 1993-1-1, where (HSSs) are largely treated as normal-strength steels in these rules, and the same design approaches are used. The behavior of high and very high-strength steel circular hollow sections under axial compression load is studied in this research. A total of 16 nonlinear finite-element (FE) models were generated to replicate stub column tests that were experimentally tested by others in previous research. Hence, a parametric study is conducted using forty FE models developed to investigate the local buckling behavior under various slenderness ratios comprehensively. The developed models cover slenderness ratios ranging from 20 to 1226 and steel grades S460 and S1100 with yield stress equal 460 MPa and 1152 MPa, respectively. The FE results were combined with 105 previously collected experimental results to assess the applicability of existing codified design methodologies in the Euro code and the North American codes of cold-formed CHS. Based on the results of this study, new cross-sectional slenderness limits and new design equations for more efficient simple designs were presented for high and very-high strength steel circular hollow sections and Compared with the results of experimental tests and FE models.

The cold-formed steel sections are becoming popular for different steel structures because it has a high resistance against the different straining actions with minimum weight compared with hard steel sections. Recently, the perforated cold-formed steel (PCFS) sections are used in many applications such as storage perforated uprights racks. Experimental research into the behaviour of steel storage rack uprights subjected to axial compression is presented in this paper. The material qualities of cold-formed steel uprights were determined by tensile tests. The seventeen perforated specimens were examined under axial compression, with five different cross-sections, three different web heights and thicknesses, and varying lengths. The study's goals are to find out how perforations affect the performance and failure mode of steel storage rack uprights, discuss the interaction of distortional and global buckling, and verify the accuracy of using the Direct Strength Method (DSM) for predicting the ultimate strength of uprights failing in buckling interactions for perforated uprights. It is found that the failure modes of perforated specimens with stiffeners generally cannot be well predicted by the Direct Strength Method. But when the modifications proposed by Xianzhong Zhao etc. al. are used, their accuracy is acceptable.

This study develops into the application of a combined MFC unit with chemical coagulation for total treatment of inert contaminants in complex substrates. Microbial Fuel Cell (MFC) technology converts chemical energy in the form of organic matter, into bioelectricity in an environmentally friendly and effi-cient manner, reducing carbon emissions and increasing bioenergy production. An evaluation of a la-boratory scale chemical coagulation using an aluminum and poly-based coagulant on how effective it can remove bulk impurities such as particulate COD and turbidity to obtain the purest and most cost-effectively treated wastewater using a jar test is being conducted in this current study. This study aims to find the most effective treatment technologies for wastewater recovery in breweries in order to achieve zero liquid effluent discharge (ZLED). The preliminary results showed that adding a modest amount of poly and a 50 % alum alone treatment improved COD, color, and turbidity reduction. The turbidity removal efficiency achieved after chemical coagulation treatment was 90.50 % and 59.36 % COD removal, demonstrating the benefits of adopting an alum/poly based technique. To determine ZLED, this study clearly advised a combined treatment technique, specifically the MFC-flocculator unit for efficient organics and inorganics removal.

The supramolecular aggregation processes occurring on metallic (aluminum and gold) surfaces in aqueous solutions of bovine serum albumin (BSA) during drying were studied using advanced scanning electron microscopy (SEM). The possible mechanism for the formation of amazing intricate fractal structures on metallic surfaces was proposed based on the analysis of SEM images, size distribution diagrams and EDX-scanning elements distribution maps.

Zinc protection of galvanized steel is initially dissolved in alkaline solutions. However, passive layer is formed over time which protects the steel from corrosion. The behavior of galvanized steel exposed to strong alkaline solutions (pH values of 12.7) with a fixed concentration of sulfate ion of 0.04M is studied. Electrochemical measurement techniques such as corrosion potential, linear polarization resistance and electrochemical impedance spectroscopy are used. Synergistic effect of sulfate ion is also studied together with other anions such as chloride Cl- or bicarbonate ion HCO3- and with other cations such as calcium Ca2+, ammonium NH4+ and magnesium Mg2+. Presence of sulfate ions can depassivate the steel, leading to corrosion density of 0.3 µA/cm2 at the end of the test. The presence of other ions in the solution increases this effect. The increase in corrosion density caused by cations and anions responds to the following order (greater to lesser influence): NH4+&gt;Ca2+&gt;Mg2+ and HCO3- &gt;Cl- &gt;SO42-.

Particle deposition on the surface of the drying chamber poses the main drawback in the spray drying process, which reduces the product recovery and affects the quality of the product. In view of this, the potential application of chemical surface modification to produce a hydrophobic surface that reduces the powder adhesion (biofouling) on the wall of the drying chamber was investigated in this study. The hydrophobic Polydimethylsiloxane (PDMS) solution was used in the vertical dipping method at room temperature to determine the optimum coating parameters on borosilicate glass and stainless-steel substrates, which were used to mimick the wall surface of the drying chamber, to achieve highly hydrophobic surfaces. A single-factor experiment was used to define the range of the PDMS concentration and treatment duration using the Response Surface Methodology (RSM). The Central Composite Rotatable Design (CCRD) was used to study the effects of the concentration of the PDMS solution (X1, %) and the treatment duration (X2, hr) on the contact angle of the substrate (°), which reflected the hydrophobicity of the surface. A three-dimensional (3D) response surface was constructed to examine the influence of the PDMS concentration and treatment duration on the contact angle readings, which serve as an indicator of the surface's hydrophobic characteristic. Based on the optimisation study, the PDMS coating for the borosilicate glass achieved an optimum contact angle of 99.33° through the combination PDMS concentration: X1 = 1% (w/v) and treatment time X2 = 4.94 hr, while the PDMS coating for the stainless-steel substrate achieved an optimum contact angle of 98.31° with PDMS concentration: X1 = 1% (w/v) and treatment time X2 = 1 hr. Additionally, the infrared spectra identified several new peaks that appeared on the PDMS-treated surfaces, which represented the presence of Si-O-Si, Si-CH3, CH2, and CH3 functional groups for the substrates coated with PDMS. Furthermore, the surface morphology analysis using the Field Emission Scanning Electron Microscopy (FESEM) showed the presence of significant roughness and uniform nanostructure on the surface of PDMS-treated substrates, which indicated the reduction of wettability and the potential effect on unwanted biofouling on the spray drying chamber.