The effect of shot peening (SP) on pre-fatigue tested carburized steel was investigated. Plane-bending fatigue tests were conducted on carburized CrMo steel that was pre-fatigue tested and treated with SP. Fatigue cracks were induced by pre-fatigue tests with a stress amplitude of σa = 1000 MPa, and the number of the pre-fatigue test cycles was 2.0 × 104 (L5 test) and 4.0 × 104 (L15 test). We compared the fatigue lives of the fatigue-damaged and smooth specimens without fatigue damage treated with the same SP. The fatigue life of the L5 tested specimens with SP was longer than that of the non-fatigue damaged smooth specimens after SP. Therefore, the fatigue cracks introduced by the L5 test can be rendered harmless by SP. Furthermore, near-surface material properties were evaluated and the mechanisms of rendering surface cracks harmless were investigated.journal articl
