A Micromechanical Approach to Model Residual Stress Relaxation and Fatigue Crack Nucleation in High Strength Gear Steels

It is well known that mechanical surface treatments, such as deep rolling, shot peening and laser shock peening, can significantly improve the fatigue behavior of highly-stressed metallic components. Of particular interest here are the residual stresses induced through shot peening process. Compressive residual stresses of high magnitudes are induced at and near the surface during shot peening process by virtue of constrained plastic deformation. These stresses enhance the service life of component by resisting fatigue crack nucleation and growth on surface of the specimen. Unfortunately, these residual stresses can relax significantly due to subsequent mechanical and/or thermal loading even under normal operating conditions.