Fatigue Strength of a Low-Alloy Steel Shot Peened with Ultra Fine Hard Steel Media

In this paper, a low alloy steel widely used in mechanical constructions has been considered and investigated. Rotating bending fatigue tests were executed both on smooth and notched samples, not peened and shot peened; different peening media and parameters were considered. In particular, new ultra fine and hard steel media were used to assess the fatigue strength increment obtained by using this media and to compare it with the fatigue strength of samples peened with conventional media. Roughness, hardness and residual stress measurements were executed to completely characterize the treated surface and to relate the surface state to the fatigue behavior. The test results show a marked positive action of the new media, enabling to obtain a strong increment of the fatigue strength even with low peening intensities.