1958 Volume 44 Issue 2 Pages 157-162
The steel will bear, generally, a crinkly, clean surface after shot-peening and therefore the authors define the "cleaning action" as such. But the authors had little informations as to the effect of cleaning on the advantage of fatigue strength, which was a proper aim of shotpeening, the influence of shot properties on the cleaning, the effect of heating on the fatigue strength thus obtained, and so on.
To get an explanations for these problems, the authors investigated the residual stress and fatigue strength of self-hardening Ni-Cr-Mo steel specimens, which had been peened with round or as-cut shots on their polished or as-rolled surfaces, the drop of fatigue limit by heating in the vacuum after peening.
Some of the new results obtained were:
1) The peening effect, which had been used somewhat vaguely hitherto, was divided into two factors; the residual stress effect and the cleaning effect.
2) The residual stress effect decreased by heating over 300°C and the cleaning effect was affected by the initial surface conditions of specimens.
3) The above-mentioned two effects took their appearances with increase of the fatigue strength.
4) The shape of shot had an influence both on the residual stress and the cleaning effect.