부산대학교 도서관

This study delves into the interplay between crystallographic texture, microstructure, and mechanical behavior in pulse laser powder bed-fused (LPBF) 316L stainless steel subjected to uniaxial tensile loading. The as-built microstructure exhibits a hierarchical arrangement spanning macro, micro, and nanoscales, showcasing chemical uniformity and minimal elemental segregation owing to the rapid cooling rate intrinsic to LPBF, distinct melt pool formations, and the emergence of nanosized silicon-rich oxides. The additive manufacturing process induces a network of dislocations, imparting twinning-induced plasticity (TWIP) behavior to 316L stainless steel. This is characterized by a distinctive five-stage strain hardening process. Maintained pre-existing dislocation networks enhance nanotwin creation, fostering interactions between different types of dislocations. Deformation-induced nanotwins contribute to a sustained elevated strain hardening rate through two stages. This effect is reinforced by the development of pronounced < 111 > and α-fiber textures, aligned with the tensile direction. Additionally, the alloy's high yield strength is attributed to the dense dislocation cell population. These dislocation cells, coupled with distributed nanooxide inclusions, facilitate the formation of nanometer-scale ductile dimples, effectively impeding crack propagation and mitigating defects compared to conventional manufacturing methods. In summary, plastic deformation hinges on dislocation glide and deformation-induced twinning, culminating in a final microstructure featuring diverse twin types and highly misoriented dislocation boundaries. This comprehensive understanding sheds light on the intricate relationship between microstructural attributes and mechanical performance in LPBF 316L stainless steel.