THE EFFECT OF SHOT PEENING ON THE NOTCH SENSITIVITY FACTOR AND NEUBER CHARACTERISTIC LENGTH FOR 7075-T6 ALUMINUM ALLOY

Abstract

This paper has been studied the effect of shot peening to improve the mechanical properties, especially the enhancement of fatigue life, also to study the effect of shot peening on notch sensitivity factor (q) for two kinds of notched circular cross-sectional area of (AA7075-T6) with radii of notches (1, 1.25 mm). Due to the dimensions of specimens and notch radius, the stresses concentration factors K_t were (1.62, 1.73), respectively. This paper was included the effect of compressive residual stresses on the Neuber characteristic length (ρ).The experiments of shot peening were carried out at two different shot peening times (SPT) (0, 8, 10, 12, 20 min). The tensile test after shot peening was done to know the improvement in mechanical properties, The surface roughness, microhardness, and the compressive residual stresses by X-ray diffraction (XRD) were measured. The results showed the maximum decreasing in notch sensitivity factor (22.35 %) and maximum increasing in Neuber characteristic length which was (270.2%) at the same shot peening time (10 min) and notch radius (1.25 mm).