1958 Volume 22 Issue 1 Pages 18-22
It is well known that the fatigue failure of structural steels is accelerated by the existence of decarburized layer on the surface of materials. In this paper, the effect of shot-peening on the fatigue strength of decarburized Si-Mn spring steels was examined by the rotary bending and the reversed torsional methods. The effect of shot-peening was very striking, and it was observed that the endurance limit at 107 cycles of decarburized steels, which was reduced by about 50% to that in the polished condition on account of the soft layer of only about 0.05 mm in thickness, was increased by 40∼50% in strength as the result of shot-peening on the decarburized layer, and it might be possible to recover the strength in the non-decarburized condition by the increase of peening intensity.