2011 巻 (2011) 56 号 p. 49-57
A series of cooperative research was conducted in order to know what extent the shot peening could increase fatigue strength of spring steel. The specimen containing a drilled hole with various depths of 0.05-0.4 mm was shot-peened at different intensities using steel shots of 0.3 and 1.0 mm in diameter. It was proved that the shot peening improves substantially the fatigue strength of specimens containing an artificial small flaw. One of the findings in this research is that the correlation of the acceptable surface defect size and shot size is observed.