ASSESSMENT OF FATIGUE BEHAVIOR FROM THE ALUMINUM ALLOY SHOT PEENED SPECIMENS

Shot peening is an effective technique of surface treatment in engineering components widely used for the introduction of residual stresses and improving the fatigue strength. The present research has evaluated the fatigue behavior from the Al 7050-T7451aluminum alloy. Shot peening process was carried out to create residual stresses using ceramic and glass shots. Axial fatigue tests were performed with base material and base material shot peened from longitudinal and transversal directions. In order to study the influence of residual stresses on fatigue life, the compressive residual stress field was measured by an X-ray diffraction method. The performance of glass shot peened Al 7050-T7451 specimens is better in comparison to ceramic shots, for longitudinal and transversal conditions. The decrease in axial fatigue strength associated to the ceramic shot process may be attributed to higher surface roughness, which acted as stress concentrators. Despite partial relaxation of the compressive residual stress for both shot peening process, they still found a beneficial effect on fatigue live for 7050-T7451 aluminum alloy.