Sliding-rolling contact fatigue and wear of maraging steel roller with ion-nitriding and fine particle shot-peening

Gears in power transmissions have been required the higher surface durability and higher wear resistance. In this study, a maraging steel was used to increase the reliability of the gears from the viewpoint of the surface durability and the wear resistance. The mechanical properties of the maraging steel are superior to those of the steel. Thus, the surface durability and wear of the aged maraging steel roller with ion-nitriding and fine particle shot-peening (FPS) were investigated under a sliding-rolling contact condition using a two-cylinder testing machine. The wear resistance of the maraging steel roller was better than that of the case-hardened steel one. The surface durability of the maraging steel roller was 70% as strong as that of the case-hardened steel one. In order to increase the surface durability of the maraging steel more, the maraging steel roller was heat-treated with ion-nitriding and FPS. Though the surface hardness of the nitrided maraging steel roller (NM) was higher than that of the maraging steel, the surface durability of the NM was about two-third as strong as that of the maraging steel one. The nitrided compound near the surface of the NM brought about the deterioration of the surface durability. The surface durabilities of the NM with FPS were inferior to that of the NM.