Improving the Wear Resistance of Alloy Steel by Isothermal Stepwise Nitriding

Abstract

The article investigates an isothermal staged nitriding process for 40KhN2MA structural steel, comprising a saturation stage in an ammonia–air mixture followed by a stage in pure ammonia. Experimental data reveal the patterns of nitride zone formation as a function of temperature and the total duration of the staged process. The effect of nitriding regimes on the growth kinetics and microhardness of the nitrided layer is examined. Tribological tests demonstrate improved wear resistance of the nitrided steel, characterized by an extended run-in period, a reduced friction coefficient, and decreased linear wear parameters. An optimal staged process regime is determined to produce a nitrided layer structure that ensures maximum wear resistance under dry sliding conditions.