SHOT PEENING EFFECT ON FATIGUE BEHAVIOUR OF SHARPLY NOTCHED STEEL SPECIMENS

Axial fatigue tests considering different stress ratios (R= σmin/σmax) have been performed on series of shot peened notched steel specimens. Residual stresses induced in specimens of each series have been characterized by X-ray diffraction measurements and the fracture surfaces have been observed by scanning electron microscopy. The results imply that the performed shot peening treatments, result in fatigue performance improvement of all series with respect to as-received specimens and that the percentage of fatigue strength enhancement varies depending on the applied peening parameters. The test results have been then elaborated with local fatigue limit criteria for life estimation of specimens in presence of high stress gradient. Comparison of the results obtained by this approach with the experimental data, provides a good approximation of the expected fatigue strength of shot peened sharply notched mechanical parts.