Wear and cracking of sintered high speed steel matrix composites in fretting conditions: A.Wronski et al. (University of Bradford, Yorkshire, UK.)

Abstract

We have investigated the microstructure and wear behavior of ion nitrided and nitrocarburized sintered steels. The specimens were steamed at 520°C after sintering at 1120°C to improve the density. Up to 0.1 mm beneath the surface the ferrite phase was developed by decarburization during steaming. A decrease in hardness at the near surface resulted from the formation of ferrite, and low hardness was recovered not by ion nitriding but by ion nitrocarburizing. It was found that the fatigue life of a steamed specimen was shorter than that of a nitrocarburized specimen, while the wear resistance properties of steamed specimens and ion nitrocarburized specimens were better than those of nitrided specimens from the pin-on-disk wear test. A mixture of abrasion and adhesion occurred on the worn surface of nitrided specimens, but abrasion was believed to be the dominant wear mechanism for the nitrocarburized specimens.