Effect of Shot-Peening on the Fatigue Strength of Metals. III : Effect on Steel with Notch

To see the effect of shot-peening on the fatigue under notched conditions, rotary-bending fatigue tests were carried out with 1-R grooved and 90°-V notched specimens of Si-Mn spring steels so heat-treated as to be of 140～150kg/mm^2 in tensile strength. The results obtained were as follows : (1) Shot-peening was more effective on notched than on polished surfaces, that is, the fatigue limits were increased by 3,33 and 73 per cent respectively in the polished, the 1-R grooved and the 90°-V notched specimens, in proportion to the notch factor ; (2) The work of peening was effective even when the shot could not reach the root of notch. Accordingly, it was concluded that shot-peening was always effective in preventing structural materials from fatigue failure under notched conditions of various types of stress concentration