Dynamic recrystallization's role in strength-ductility trade-off in polycrystalline Fe–Cr–Ni stainless steels produced by laser powder bed fusion

Abstract

Abstract The deformation mechanisms and reasons for excellent ductility in additively manufactured Fe–Cr–Ni stainless steels by laser powder bed fusion (L-PBF) were disclosed by an interrupted tensile test at room temperature, electron backscattered diffraction, and transmission electron microscopy. The results showed dislocation (DL) slip starts at low strain values, resulting in a rearrangement of DLs and reorientation of low angle grain boundaries along with shear bands. At higher strain values, deformation twins intersect with other twins, DLs, stacking faults, and grain boundaries. In addition to planar slip and twining-induced plasticity (TWIP), dynamic recrystallization (DRX) was observed during deformation due to the formation of a high density of DLs during L-PBF. Different deformation and DRX mechanisms are disclosed in detail, including their origin, sequences, and interplay. The results presented in this paper opens a new operation window for the other types of TWIP steels, such as medium and high Mn steels to be manufactured by the L-PBF to maximize their energy impact.