Finite-element analysis of random shot peening in Inconel 718: Effects of shot size, coverage, and impact sequence

This study investigates the control of the residual stress field and surface topography during shot peening of the Inconel 718 alloy. A random shot-peening modeling method based on the Poisson Disk Sampling (PDS) algorithm is proposed to systematically investigate the effects of shot diameter, coverage, and combined-diameter peening sequences on strengthening outcomes. The results show that shot diameter governs the depth characteristics of the compressive residual stress field: larger shots markedly increase both the peak compressive residual stress and the thickness of the affected layer, but they also tend to increase surface roughness. Increasing coverage enhances cumulative plastic deformation, driving the residual stress toward higher compressive magnitudes and greater depths. In addition, the sequence of shots with different diameters in dual shot peening has a pronounced influence on surface stress uniformity and roughness: the “large-then-small” sequence promotes a more uniform surface compressive stress distribution and better controls roughness, whereas the “small-then-large” sequence can yield higher local compressive peaks but tends to leave low-stress regions and poorer uniformity. This work provides theoretical guidance and numerical tools for optimizing shot-peening processes for Inconel 718 components across multiple service conditions, enabling coordinated control of the residual stress field in terms of magnitude, depth, and uniformity.