Residual stress field of HIPed silicon nitride rolling elements

Abstract

The residual stress field of HIPed Si 3N 4 rolling elements were studied. Two kinds of HIPed Si 3N 4 ball blanks self-finished at different nominal lapping loads ranging from 1.3 to 10.87 kgf/ball and four kinds of commercially finished 1/2 in (12.7 mm) HIPed Si 3N 4 balls before, during and after RCF tests were investigated. The experimental results showed that in the finishing process of HIPed Si 3N 4 rolling elements, the surface and subsurface compressive residual stress induced is proportional to the lapping load applied. There was initially a high compressive residual stress layer on the HIPed Si 3N 4 ball blanks and this layer is mostly removed during the finishing process. During the rolling contact fatigue process of HIPed Si 3N 4 rolling elements, the residual stresses on the rolling track will change dramatically as RCF proceeds.