Additive-Manufacturing-Induced Cell Structure in Stainless Steel 316L: 3D Morphology and Formation Mechanism

Abstract The 3D morphology of the additive-manufacturing-induced cell structure is characterized and its formation in austenitic stainless steel 316L fabricated by laser powder bed fusion is analyzed. The experimental results demonstrate that the cell structure has a 3D prism-like morphology with a crystallography-dependent spatial orientation. The formation of the cell structure is discussed. It is proposed that both the liquid–solid transformation and thermal strain contribute to the formation: the initial cells form during the liquid–solid transformation, and the final dislocation cell structure is shaped by thermal-stress-induced deformation during cooling and subsequent thermal cycles.