Abstract
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.
