Optimization of Sintering Parameters of 316L Stainless Steel for In-Situ Nitrogen Absorption and Surface Nitriding Using Response Surface Methodology

This research investigates the simultaneous sintering and surface nitriding of 316L stainless steel alloy using powder metallurgy method. The influence of sintering temperature and dwell time are investigated for maximum nitrogen absorption, densification and increased microhardness using response surface methodology (RSM). In this study, 316L stainless steel powder was compacted at 800 MPa and sintered at two different temperatures of 1150 and 1200 degrees C with varying dwell times of 1, 3, 5 and 8 h in nitrogen atmosphere. The sintered compacts were then characterized for their microstructure, densification, microhardness and nitrogen absorption. The results revealed that increased dwell time assisted nitrogen to diffuse into stainless steel matrix along with the creation of nitride layer onto the sample surface. The microhardness and density also increased with increasing dwell time. A densification of 7.575 g/cm(3) and microhardness of 235 HV were obtained for the samples sintered at 1200 degrees C temperature with 8 h dwell time. The simultaneous sintering and surface nitriding technique developed in this research work can help in improving corrosion resistance of this material and controlling leaching of metal ions for its potential use in biomedical applications.