Diaz, J.C.; Watanabe, K.; Rubio, A.; De La Cruz, A.; Godinez, D.; Nabil, S.T.; Murr, L.E.; Wicker, R.B.; Arrieta, E.; Medina, F. Effect of Layer Thickness and Heat Treatment on Microstructure and Mechanical Properties of Alloy 625 Manufactured by Electron Beam Powder Bed Fusion. Materials2022, 15, 7767.
Diaz, J.C.; Watanabe, K.; Rubio, A.; De La Cruz, A.; Godinez, D.; Nabil, S.T.; Murr, L.E.; Wicker, R.B.; Arrieta, E.; Medina, F. Effect of Layer Thickness and Heat Treatment on Microstructure and Mechanical Properties of Alloy 625 Manufactured by Electron Beam Powder Bed Fusion. Materials 2022, 15, 7767.
Diaz, J.C.; Watanabe, K.; Rubio, A.; De La Cruz, A.; Godinez, D.; Nabil, S.T.; Murr, L.E.; Wicker, R.B.; Arrieta, E.; Medina, F. Effect of Layer Thickness and Heat Treatment on Microstructure and Mechanical Properties of Alloy 625 Manufactured by Electron Beam Powder Bed Fusion. Materials2022, 15, 7767.
Diaz, J.C.; Watanabe, K.; Rubio, A.; De La Cruz, A.; Godinez, D.; Nabil, S.T.; Murr, L.E.; Wicker, R.B.; Arrieta, E.; Medina, F. Effect of Layer Thickness and Heat Treatment on Microstructure and Mechanical Properties of Alloy 625 Manufactured by Electron Beam Powder Bed Fusion. Materials 2022, 15, 7767.
Abstract
This research program investigated the effects of layer thickness (50 and 100 microns) on the microstructure and mechanical properties of electron beam powder bed fusion (EBPBF) additive manufacturing of Inconel 625 alloy. The as-built 50 and 100 micron layer thickness components were also heat treated at temperatures above 1100 oC, which produced a recrystallized grain structure containing annealing twins in the 50 micron layer thickness components, and a duplex grain structure consisting of islands of very small equiaxed grains dispersed in a recrystallized, large-grain structure containing annealing twins. The heat treated component microstructures and mechanical properties were compared with the as-built components in both the build direction (vertical) and perpendicular (horizontal) to the build direction. Vickers microindentation hardness (HV) values for the vertical and horizontal geometries averaged 227 and 220 for the as-built 50 and 100 micron layer components, and 185 and 282 for the corresponding heat treated components. The yield stress values were 387 MPa and 365 MPa for the as-built layer horizontal and vertical 50 micron layer geometries, and 330 MPa and 340 MPa for the as-built 100 micron layer components. For the heat treated 50 micron components, the yield stress values were 340 and 321 MPa for the horizontal and vertical geometries, and 581 and 489 MPa for the 100 micron layer components, respectively. The elongation for the 100 micron layer as-built horizontal components was 28% in contrast to 65% for the corresponding 100 micron heat treated layer components, an increase of 132% for the duplex grain structure. However, the coarse grains containing annealing twins and the equiaxed small grain islands in the duplex structure for the heat treated components contained continuous carbides in the grain boundaries, and this may indicate sensitization and a reduction in corrosion resistance. These findings point to the potential mechanical property advantage for heat treatment of Inconel 625 alloy 100 micron layer thickness components fabricated by EBPBF.
Keywords
electron beam powder bed fusion (EBPBF); Inconel 625; microstructure and mechanical properties; layer-thickness effects; heat treatment; duplex grain structure; grain boundary carbides
Subject
Chemistry and Materials Science, Metals, Alloys and Metallurgy
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
