The post-weld heat treatment (PWHT) cracking susceptibility of a coarse grain heat-affected zone (CGHAZ) in SA213-T23 (2.25Cr-1.6W steel), used for boiler tubes employed in thermal power plants, was investigated using a Gleeble thermal cycle simulator. The PWHT cracking susceptibility test was performed at 650℃, 700℃ and 750℃, and it can be judged that the lower the reduce of area, the more susceptible it is to PWHT cracking. The results of the test also showed higher cracking susceptibility at 650℃ and 700℃, mostly involving intergranular fracture, while at 750℃, transgranular fracture was exhibited. Therefore, the PWHT cracking susceptibility is considered to be closely related to grain boundary. The microstructure of the simulated CGHAZ and PWHT at 650℃, 700℃and 750℃ was observed after etching with nital and alkaline sodium picrate etchants. Alkaline sodium picrate etched microstructures showed a white band at the grain boundary at 650℃, 700℃ and 750, that did not appear in nital etching. Analysis of the white band using EPMA, TEM and nanoindentation revealed that it was intergranular ferrite depleted with C, W and Cr as compared to that in the matrix. Based on these results, we investigated the mechanism of intergranular ferrite formation during PWHT and its effect on PWHT cracking susceptibility at 650℃, 700℃ and 750℃.

This paper investigates the evolution of microstructures and precipitations of an ultra-low iron alloy 625 subjected to long term aging treatment by scanning electron microscope (SEM) and X-ray diffraction(XRD). Use ASTM G28A acid Fe3(SO4)2 erosion to represent intergranular corrosion weightlessness and corrosive morphology. The result shows that alloy at 750C by aging treatment for 40h, precipitated γ'' phase in the grain boundary. In high density area of γ'' phase, occurs γ'' phase to δ phase degeneration transformation by aging treatment for 200h and the needle-like δ phase becomes more with time prolonged. And γ'' phase degenerated to δ phase completely until treated for 1000h. The sample which has aging treatment tends to have intergranular corrosion and mainly because alloy element spreading leads to dilution area and grain boundary precipitated phase, plus interlaced δ phase’s dissolving, which makes sample grain particle fall off and this results in apparent weightlessness. The weightlessness rate(WLR) is related with precipitated volume score. With aging sensitization time change, can be described by Johnson-Mehl-Avrami equation, i.e.: $WLR=44.32\left[1-\text{exp}\left(-\frac{t}{10.99}\right)\right]+44.62\left[1-\text{exp}\left(-\frac{t}{327.8}\right)\right]+1.267\left(mm/a\right)$

The municipal water supply, related mainly to the cities of Albanian, began to develop in the second half of the 19th century and much intensively after 1945. Today the reported mean water production for the cities, on average, is about 300 l/capita/d including drinking and industrial water supply. The territory of Albania consists of uneven distribution of very heterogeneous aquifers conditioning the reach variety of the municipal water supply solutions. In this article are analyzed and classified the hydrogeological aspects of water supply sources of the settlements, which are summarized in five groups: (a) Wells in alluvial intergranular aquifers; (b) karst springs; (c) wells in karst aquifers; (d) springs in fissured rocks, and (e) mixed water sources. For each group of the water supply sources the main concerns regarding the quantity and quality problems are analyzed facilitated by the description of a variety of representative examples of different situations. Based on the gained experience important recommendation are given for the better understanding of hydrogeological aspects of water supply systems emphasizing the problematics along the river water recharge areas and on the seawater intrusion in coastal aquifers, as well as on transboundary aquifers. However, the main problems of public water supply of Albania remain the poor management of water supply systems which is reflected in the e high water losses, as well as the low public awareness of request for sustainable use.