Plastic anisotropy and deformation-induced phase transformation of additive manufactured stainless steel

Chae, H.*; Huang, E.-W.*; Jain, J.*; Wang, H.*; Woo, W.*; Chen, S.-W.*; Harjo, S.   ; Kawasaki, Takuro   ; Lee, S. Y.*

Plastic anisotropy and deformation-induced phase transformation of additively manufactured (AM) stainless steels were investigated via in-situ neutron diffraction, electron backscatter diffraction, metallography, and fractography. Two types of tensile specimens were manufactured: (1) One sample was vertically fabricated with its tensile axis parallel to the z-direction (AM-V), (2) The other sample was horizontally fabricated with its tensile axis perpendicular to the z-direction (AM-H). A commercial 15-5PH stainless steel (CA) was used for comparison. AM steel revealed enhanced yield strength, tensile strength, and uniform elongation over CA, which was mainly due to grain refinement and transformation induced plasticity (TRIP). Different onsets of strain nonlinearity between AM-V and AM-H were closely related to martensitic phase transformation.