Tribological behaviour of plasma based low energy nitrogen ion implanted AISI 316 austenitic stainless steel against same stainless steel counterface

Abstract

Tribological properties of a single high nitrogen face centred cubic phase γ_N layer formed on the plasma based low energy nitrogen ion implanted AISI 316 austenitic stainless steel were investigated on a ball on disc tribometer against the same stainless steel counterface under a normal load of 2 N with a sliding speed from 0·16 to 0·39 m s⁻¹. The microhardness of the γ_N phase layer with a thickness of ∼13 μm and a nitrogen peak concentration of ∼35 at-% was measured to be ∼22 GPa. During the sliding for 1 h, the faint wear tracks of the γ_N phase layer against the same stainless steel ball were observed with all the sliding speeds. The friction coefficient of the γ_N phase layer changed in the range from 0·85 to 0·70 with increasing sliding speed. Formation of the γ_N phase layer on the stainless steel significantly improved the wear resistance of the stainless steel against the same stainless steel. An oxidative wear mechanism of the γ_N phase was found instead of an adhesive wear mechanism of the original stainless steel because the γ_N phase was prone to tribochemical oxidation on the worn surface due to the nitrogen supersaturation in austenite matrix.