Effect of hydrogen on flaking and fatigue cracking during compressive fatigue test of bearing ball

Abstract

The effect of hydrogen on flaking and fatigue cracking in contact compressive fatigue of SUJ2 bearing steel were investigated using steel ball having artificial small hole. In this study, compressive fatigue test up to 10⁷ cycles were carried out in 3 different environment : 1) 70 MPa high-pressure hydrogen, 2) ambient air and 3) 10^-5 Pa high vacuum. In cases of high-pressure hydrogen, crack was initiated in all steel balls. on the other hand, in case of vacuum, there are no flaking. Therefore, it is seemed that hydrogen diffused to steel ball was harmful to fatigue properties of steel ball. But, in this time, there are no white etching area (WEA) at the flaking part of steel balls.