Research on mechanical properties and microstructure by selective laser melting of 316L stainless steel

Abstract

Selective Laser Melting (SLM) and Selective Laser Remelting (SLR) were employed to fabricate 316 L stainless steel in this work. Mechanical properties, microstructure were investigated. The results showed that scanning speed had little effect on Young modulus, but large effect on yield strength, tensile strength,elongation and surface roughness for SLM. Additionally, young modulus, tensile strength, elongation, and relative density changed from 3.8 GPa to 14.3 GPa, 667 MPa to 725 MPa, 37.3% to 40.8%, 91.6% to 99.3% for SLM and SLR process, respectively, so the mechanical properties, including strength and plasticity of 316 L stainless steel can be improved by suitable Selective Laser Remelting process. In addition, fracture characteristics, strengthening mechanisms, and crack propagation types were studied by SEM, EDS. The results showed that excessive surface roughness, low metallurgical bond between layers, internal defects (balling, liquid splashing, pores, bubbles, etc) and low atomic binding force lead to crack propagation and decreased mechanical properties.