In order to investigate the influence of fine particle bombarding on the surface fatigue strength of carburized steel under a sliding-rolling contact condition, 2 kinds of bombarded plates were fatigue tested using a thrust bearing testing machine. The same fatigue tests were peiformed also by using as-carburized plate and surface-finished plate by grinding for the comparison. The fatigue test results were discussed statistically by means of non-parametric test and Weibull distribution. The surface roughness of the bombarded plates were almost the same as that of ground plate. From the results of Wilcoxon signed-rank tests, the fatigue life of the bombarded plate with a particle diameter of 50μm was longer than that of as-carburized one under a significance level of 5%. It was clarified from the statistical analysis that the fine particle bombarding process after carburizing causes the longer life for the carburized plate.
