Abstract: Low temperature plasma nitriding was performed in order to study the effect of processing parameters like treatment time, nitrogen and carbon content on the expanded martensite layer (α'N layer) of the AISI 420 martensitic stainless steel. Plasma nitriding was carried out for various times from 4 to 15 h, with changing the nitrogen content from 10% to 35 % and carbon content from 0% to 6% at fixed temperature of 400°C. The surface hardness and α'N layer thickness values increases with increasing processing time and increasing the nitrogen content. Contrary, these values decreases with increasing the methane content. The highest surface hardness (around 1330 HV0.1) and highest α'N layer thickness (around 33 µm) were achieved when treated with 25% nitrogen content for 15 h. Although, this longer processing time exhibits poor corrosion resistance. The corrosion resistance decreases with increasing methane content. Best corrosion resistance is achieved when treated with 25% nitrogen content for 6 h, without any methane content.
Keywords: AISI 420 martensitic stainless steel, α'N layer, Corrosion resistance, low temperature plasma nitriding, hardness.
Date Published: February 19, 2020 DOI: 10.11159/ijmmme.2020.002View Article