Fretting Wear of a High-Performance Plasma Nitrided Steel

Plasma nitriding is applied on the surface of a kind of high-performance bearing steels. The microstructure and the microhardness of the nitrided layer are analyzed, and the fretting friction and wear properties of the plasma nitrided steel are investigated at the SRV IV tribo-meter at room temperature. The results indicate that the surface of every plasma nitrided sample formed a higher hardness layer, the maximum hardness of the layer was as 2.8 times as that of the matrix. Without lubrication, the friction coefficient and wear volume are reduced approximately by 25%, 80%, respectively, and the wear mechanisms of nitrided specimens are oxidation wear and spalling wear of oxides. Under oil lubrication, the friction coefficient and the wear volume are reduced approximately by 36% and 97%, respectively, and the wear mechanisms of nitrided specimens are abrasive wear and fine massive spalling by crack extension. Plasma nitrided sample shows much better wear resistance than that the substrate.