Mapping the Accouterment Effects of Plasma Nitriding on AISI 316L in Biomedical Applications

Abstract

The present study aimed to critique the corrosion resistance of plasma-nitrided films of AISI 316L stainless steel with regards to their biomedical applications. The plasma nitriding process improves austenitic stainless steel’s micro-hardness and corrosion resistance. Austenitic stainless steel was treated at a temperature of 470 °C for 12, 24, and 36 h, to observe the outcomes of plasma nitriding. The corresponding microstructure, microhardness, depth of the nitrided layer, and electrochemical parameters were systematically characterized. The corrosion resistance of the plasma-nitrided specimens was gauged using the weight loss method in simulated body fluids (Phosphate-buffered saline (PBS), saline water, and ringer solution) by static immersion for 9, 18, and 27 days. Optimization was catalogued using the Taguchi method L27 orthogonal array to determine the optimum combination of plasma nitriding time and immersion time in simulated body fluid. The material characterization showed that the corrosion resistance of the plasma-nitrided specimens improved with longer nitriding times by Tafel polarization curves. Microhardness was observed at 12, 24, and 36 h as 1060, 1150, and 1220 HV0.1. SEM, with an energy-dispersive X-ray analysis (EDS) used to characterize the surface before and after plasma nitriding testing. It was concluded that CrN, which precipitates during processing and contributes to the loss of chromium from the surrounding matrix and the onset of a corrosive environment, is the primary cause of this behaviour.