Raceway Grooving: A Tool for Monitoring Microstructural Changes

摘要

Classic rolling contact fatigue failures are generally the consequence of cracks originating from defects in the material. This is why steel makers have put a lot of effort over the years into manufacturing bearing steels with low amounts of impurities. However, for any given impurity level, the rolling contact fatigue (RCF) life is governed by the microstructural stability of the steel matrix. The measurement of raceway grooving, which is a consequence of the sub-surface microstructural changes that occur when steel is exposed to dynamic stressing, allows for a simple indirect method to follow the evolution of these gradual sub-surface changes. This paper presents a method for assessing the RCF performance of high strength rolling bearing steels which is being employed at Ovako Hofors. This involves the measurement of the groove formation at the raceway surfaces of simple RCF test configurations for screening suitable bearing steel compositions. Results from bearing steels with varying resistance to microstructural changes will be presented and compared with an SAE 52 100 baseline.