Atomistic investigation on the correlation between shot peening impact energy and grain microstructure

HT Dong and JY Tang and JH Zhang and WW Huang and LL Lv, JOURNAL OF MATERIALS SCIENCE, 60, 21952-21983 (2025).

DOI: 10.1007/s10853-025-11659-y

The paper uses molecular dynamics simulation to reveal the extreme plastic deformation behavior of polycrystalline iron under shot peening. We investigated the effects of three key factors, particle diameter, velocity, and incident angle, on stress state, dislocation distribution, and surface accumulation. The results are: (1) When the impact energy is the same, particle diameter has the best impact on dislocation nucleation, and velocity has the greatest impact on residual compressive stress. (2) An increase in impact energy is beneficial for dislocation proliferation and enhancing surface residual compressive stress. The residual compressive stress becomes difficult to accumulate due to the increase in contact area for particle diameter. (3) As the impact energy increases, the plastic deformation area around the indentation pit expands, the plastic accumulation increases, and the surface roughness deteriorates. (4) The mechanism of increased impact energy and grain refinement is: under extreme plastic deformation, the extrusion produces huge shear stresses to drive the atomic movement, and the obstruction of the surrounding grains forces the local lattice orientation to change to produce new small grains. This study contributes to a more profound understanding of the nanoscale deformation mechanisms associated with shot peening impact energy.

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