Effect of High Laser Energy Density on Selective Laser Melted 316L Stainless Steel: Analysis on Metallurgical and Mechanical Properties and Comparison with Wrought 316L Stainless Steel.

Abstract

The austenitic 316L stainless steel (SS) is used extensively for marine applications as well as in construction, processing, and petrochemical industries due to its outstanding corrosion resistance properties. This study investigates the density, microhardness, and microstructural development of 316L SS samples fabricated by selective laser melting (SLM) under high laser energy densities. The selective laser melted (SLMed) specimens were fabricated under high laser energy densities (500, 400, and 333.33 J/mm³) and their metallurgical and mechanical properties were compared with the wrought specimen. SLMed 316L SS showed excellent printability, thereby enabling the fabrication of parts near full density. The porosity content present in the SLMed specimens was determined by both the image analysis method and Archimedes method. SLMed 316L specimens fabricated by the SLM process allowed observation of a microhardness of 253 HV_1.0 and achieved relative density up to 98.022%. Microstructural analysis using optical microscopy and phase composition analysis by X-ray diffraction (XRD) has been performed. Residual stresses were observed using the XRD method, and compressive stress (-68.9 MPa) was noticed in the as-printed specimen along the surface of the build direction. The microstructure of the as-built SLMed specimens consisted of a single-phase face-centered cubic solid solution with fine cellular and columnar grains along the build direction. The SLMed specimens seemed to yield better results than the wrought counterpart. IRB approval and Clinical Trial Registration Number are not applicable for this current work.