Wear Resistance of Nitrogen-Modified High-Alloy Steels Under Friction Conditions without Lubricant

For a high-strength coating–base layered material with different values of the thickness of the strengthened layer, finite element modeling of the stress-strain state formed during friction was carried out. It is shown that with a decrease in the thickness of the coating, a significant increase in the level of shear stresses acting in the base during friction is recorded. The patterns of wear under dry friction conditions of AISI 304 and AISI 420 high-chromium steels modified with nitrogen ions, differing in the hardness of the base and the thickness of the nitrided layer, have been studied. It is concluded that the abnormally high wear rate of a thin nitrided layer in AISI 304 steel is associated with the accumulation of shear strains in the plastic austenitic base during friction, as well as with a high gradient of hardness values along the depth of the hardened layer in the steel and a γ → α phase transformation in the base during frictional interaction. The influence of base hardness on the wear resistance of AISI 420 nitrided steel was studied. It has been established that an increase in the hardness of the AISI 420 steel base leads to a decrease in the wear rate of thin nitrided layers at the later stages of tribological tests, which is associated with a slowdown in the accumulation of shear strains in the solid steel base during friction.