Contact Durability of Steels After Ion Nitriding in Hydrogen-Free Media

We study the durability of 20, 40Kh, ShKh15, and Kh12М steels under the conditions of rolling friction in І-20 oil. The tests for contact durability were performed without heat treatment and after quenching with the use of thermochemical technology of ion nitriding in hydrogen-free saturating media and a complex technology nitroquenching under the conditions of point and linear contact. The influence of loading and the hardness of the substrate on the “coating–substrate” composition is investigated. The prospects of application of the technology of hydrogen-free ion nitriding for increasing the durability of structural elements under the conditions of rolling friction is revealed by the results of comparative testing for contact durability. It is demonstrated that the contact durability of the “coating–substrate” composition rectilinearly increases with the hardness of the substrate and decreases as the load increases according to a nonlinear law.