The effects of SLM process parameters on the relative density and hardness of austenitic stainless steel 316L

Abstract

Selective Laser Melting (SLM) process parameters significantly influence the microstructure and mechanical properties of the final product. Using the Taguchi optimization method, this investigation refined 316L austenitic stainless steel SLM process parameters. Process factors included laser power, scanning speed, and layer thickness, while performance criteria included relative density and hardness. A laser power of 180 W, a scanning speed of 1200 mm/s, and a layer thickness of 0.03 mm produced optimal results, resulting in 125 J/mm3 energy density and a hardness of 220 HV. ANOVA analysis also showed that power influenced density by 27.49 %, scanning speed by 45.51 %, and layer thickness by 23.60 %. A parameter combination led to materials with impressive tensile strengths (649 ± 4 MPa), yield strengths (409 ± 3 MPa), and elongation (42 ± 1 %) for increasing scanning speed and lowering energy density, resulting in a decrease in ultimate strength. A SEM analysis of fracture characteristics was also conducted. As a result of a cellular microstructure, ductile dimple sizes were limited to the nanoscale, and crack propagation was impeded through a pinning effect, thus increasing defect tolerance in the SLM SS316L. According to the findings, internal defects play a significant role in crack propagation and subsequent reduction of mechanical properties.

Keywords

• Additive manufacturing
• SLM
• AISI 316L
• Mechanical properties
• Density