AN X-RAY-DIFFRACTION STUDY OF THE RESIDUAL-STRESS STRAIN DISTRIBUTIONS IN SHOT-PEENED 2-PHASE BRASS

X-ray residual stress distribution and line-broadening analysis were used to study the deformation distributions existing in the surface layers of a shot-peened two-phase brass specimen. The results indicate inhomogeneous partitioning of the plastic strains between the alpha and beta grains, as well as between the surface layers and the bulk. The residual microstresses, which occur because of the differential deformation between the alpha and beta grains, have a maximum in the beta grains at the material surface, while the residual macrostresses, which arise because of the differential plastic deformation between the surface and the bulk, exhibit a maximum deeper in the material. A qualitative model is presented.