Evaluation of microstructure and microhardness of AISI 316L stainless steel manufactured by laser-directed energy deposition

Abstract

Laser-Directed Energy Deposition (L-DED) technique can create an object on substrates through line-by-line deposition. AISI 316L stainless steel is employed across diverse industries, including aerospace, medical, automotive, and marine sectors. The present research investigated the additive manufacturing of AISI 316L stainless steel using the L-DED system. The microstructure and hardness of the AISI 316L bulk sample are analyzed using optical microscopy and a microhardness tester. The microstructure in the AISI 316L bulk sample showed an equiaxial and columnar dendritic structure. Furthermore, The center of the melt pool had a fine dendritic structure, while the boundary of the melt pool had a coarse dendritic structure. Microstructural defects including lack of fusion and gas porosity were observed. The lack of fusion was mainly observed at the interface of the layers. The hardness in different parts of the sample varied from 265 HV to 356 HV.