Influence of shot peening on rolling fatigue life of case-hardened steel

In this paper, the thrust type rolling fatigue tests for case-hardened steel disks treated by normal shot peening technique with a shot of 0.6mm and fine particle peening technique with a shot of 0.05mm are done, respectively. The surface hardness and the surface compressive residual stress of the steel disks are increased by the peenings. On the other hand, the surface roughness and the D value of steel disks are decreased by fine particle peening. According to the test results, rolling fatigue life of the tested steel disks is improved by fine particle peening, and is not improved by normal shot peening relatively. Further, the test confirms that by using fine particle peening technique with larger air pressure, not only the fatigue strength improvement but also the surface figure of the material can be controlled. It is concluded that the fine particle peening technique can be used as a new surface reforming method for machine parts.