The present work investigated that the influence of shot peening condition on the fatigue strength when the compressive residual stress of 2000 MPa or more was given to the carburizing steel. The fatigue strength is improved more than the conventional shot peened specimens. Considering the fatigue crack propagation process, the fatigue crack propagation tends to be obstructed by giving the compressive residual stress to a large, deeper area, and to improve the fatigue strength. The fatigue strength changes by the quality situation of the surface. In the case of giving a high compressive residual stress to the surface, it is necessary to consider not only the fatigue crack progagation but also the cracking as an influence on the fatigue strength.
