Effect of Specimen Hardness on Relaxation Behavior of Compressive Residual Stress during Fatigue Process

Abstract

Compressive residual stress formed by fine particle peening improves the fatigue properties of steel. However, it is relaxed during the fatigue process particularly during the first cycle of fatigue because of the compressive residual stress layer yield. In this study, the compressive residual stress was induced for specimens with different yield strength by fine particle peening, and the residual stress relaxation behavior was measured and compared using in situ X-ray stress measurement. The results showed that the higher the hardness of the base metal, the higher was the compressive residual stress formed. Moreover, the residual stress was more stable during the fatigue process for a substrate of higher hardness compared to that formed for a substrate of a lower hardness. This is due to the difference in the yield stress.