Hardening mechanism of Cr5 backup roll material induced by rolling contact fatigue

The hardening mechanism of Cr5 backup roll material induced by rolling contact fatigue was studied. X-ray diffraction, Optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to investigate the effect of microstructure alternations induced by fatigue on the hardness change. Remarkable change was observed at the half value breadth of X-ray diffraction under microstructure alternates which resulted from rolling contact fatigue. The OM photos showed obvious white etching areas (WEAs) in the layer influenced by fatigue, reflecting that some kind of content or structure with high etching resistance was generated in the layer influenced by fatigue. Microstructure changes such as nano-sized carbides precipitation and nanocrystalline formation induced by fatigue were observed in the site where the peak of half value breadth of X-ray located. These changes of microstructure should be considered in the mechanism for hardening of Cr5 backup roll material due to rolling contact fatigue.