1957 Volume 43 Issue 5 Pages 533-537
The relationship between the residual compressive stress in specimen, resulting from shot peening, and the fatigue strength of it is studied. Si-Mn steel specimens are polished to 000, peened with hard or soft (round or as-cut) cut-wire shots, and tested with the 200kgm Schenk type fatigue-testing machine.
Conclusions reached are:
1) Residual compressive stress distinctly improves the fatigue resistance of peened specimen, but the investigations into the numerical correlation between the former and the latter are left to be studied.
2) Hardness of shots has a meaning only in relation to the ability of causing residual stress in specimens, then the softer shot is not always inferior to the harder one; i.e., the hardness number of shot will take a clear meaning only after the hardness of the work to be peened is shown.
3) The use of as-cut shot has a reverse effect upon the fatigue strength of the work, and the existence of comparatively high residual stress caused in the work will not prevent the fatigue limit from decreasing widely, if the bulk of as-cut shots is applied in peening practice.