A Relationship Between Manufacturing Routes-Microstructure-Biotribology of Selective Laser Melted Stainless Steel 316L Under Dry and Simulated Body Fluid

This study aims to compare the microstructural and biotribological behavior of additively manufactured and commercially available stainless steel 316L (SS 316L) implants under simulated body fluid. The surface integrity, microstructures, and micro-hardness characterizations were performed. FESEM micrographs and 3D surface profiles dictate that the specimen is manufactured using a bi-directional 67º rot-scanning strategy. Further, the microstructure, XRD, and micro-hardness outcomes dictate that the selective laser melted (SLMed) sample has an anisotropic fine-grained (18.49 µm) gamma austenite phase with an improved hardness of 280.35HV_0.05, which is 146% higher compared to casted counterpart. In-vitro state biotribological results indicate that the SLMed part has a minimum coefficient of friction (COF: 0.287) value under simulated body fluid, which is 58% less than the casted part (COF: 0.494), and an improved volumetric wear loss at different loading conditions was also observed. The obtained outcomes dictate that selective laser melting is a better processing route to manufacture SS 316L permanent implants with enhanced microstructural, mechanical, and biotribological behavior.