Short Time Ion Nitriding of AISI 420 Martensitic Stainless Steel to Improve Wear and Corrosion Resistance

Abstract

Plasma nitriding has become a powerful tool to improve wear resistance of stainless steels and sustain or improve corrosion resistance with an adequate selection of process parameters. In this work, the short treatment route with temperatures above 400ºC was selected for AISI 420 stainless steel. After the nitriding process, a wide nitrided layer, with good wear and corrosion properties was simultaneously obtained with selected parameters. A 5 hours treatment at 420 ºC resulted in a 10 µm nitrided layer. XRD revealed an expanded Fe-α layer with Fe nitrides but no signal of CrN was found. Wear resistance was improved three and four times in erosion and sliding tests compared to the non-nitrided material. Corrosion resistance was tested in anodic polarization experiments in a NaCl solution. In this test, the samples treated in the short time process presented the best results.

Keywords

• Plasma nitriding
• martensitic stainless steel
• erosion
• corrosion