A Numerical Study Comparing The Effect on Residual Stresses of Two Different Types of Projectiles During Shot Peening

Shot peening is a widely used technique to improve fatigue life in metallic alloys. This processing technique introduces a subsurface compressive residual stress field through a plastic deformation of the surface caused by the impact of a large number of high-speed projectiles. There are a number of parameters that affect the residual stress field depth and magnitude. The effects of the impact angle, shot speed and shot geometry are currently being researched. In particular, substituting spherical cast shots by cylindrical cut wire shots is an attractive option, especially in terms of cost. The effect of shot geometry on residual stresses, however, needs to be further investigated. Because industrial-scale experimentation is costly and cumbersome, mathematical modeling offers a convenient alternative to carry out this type of research. The present work shows a comparison between the residual stresses generated by the impact of spherical and cylindrical projectiles on a steel substrate. This threedimensional model was developed using ABAQUS finite element commercial software (Release 6.12, Dassault Systémes, France). The results show that cylindrical shots generate residual stress fields that are higher in magnitude than those generated by a spherical shot. However, the residual stress field of cylindrical shots impacting the surface at an oblique angle shows an important degree of asymmetry. This effect is not found when spherical shots impact the surface at the same oblique angle.