Effect of process atmosphere on microstructure, melt pool, texture, precipitate characteristics, and mechanical properties of laser powder bed fusion Fe-12Cr-6Al

Abstract

This study investigates the impact of atmospheres (Ar and N2) on Fe-12Cr-6Al alloy fabricated using laser powder bed fusion (L-PBF) in terms of melt pool shape/size, microstructure, precipitate characteristics, and mechanical properties. The sample built in the N2 atmosphere exhibited lower porosity, wider melt pools, and no Al2O3 agglomeration. Oxygen content decreased from 0.012 to 0.0045 (wt.%), and nitrogen content increased from 0.013 to 0.02 (wt.%). The Ar-printed sample had a yield strength (YS) of 232 ± 15 MPa, ultimate tensile strength (UTS) of 286 ± 10 MPa, and total elongation (TE) of 6.4 ± 1.3 %, while the N2-printed sample showed significant improvements of the mechanical properties: YS of 315 ± 11 MPa, UTS of 401 ± 11 MPa, and TE of 7.8 ± 1.1 %. Therefore, N2 might be considered to replace Ar as a cost-effective shielding gas for FeCrAl alloys, with improved properties.