Parametric Two-Dimensional Finite Element Investigation: Shot Peening of High-Strength Steel

Abstract

A parametric two-dimensional transient dynamic FEM is used to investigate the influence of two shot-peening specifications used on 4340M (300M) high-strength steel. One uses cast steel nominally 15 % softer than the target, the other nominally 15% harder than the target. Details of the FEM development are provided. The FEM is then used for individual investigations carried out on the merits of the two shot specifications. A 24 factorial experimental design uses parametric variations of the FEM to detect the significance of shot diameter, velocity, target thickness and frictional coefficient on five response variables that include the following: the residual stress at the target surface and at the profile minimum, the depth corresponding to the minimum compressive residual stress, transition depth (near-surface compression to core tension) and the plastic work done on the target (percentage of initial kinetic energy). Deterministic linear models are generated for each response for both shot specifications using a completed factorial design approach. Probabilistic standard errors are estimated based on a normal distribution of the relative hardness between the shot and target using their yield strengths as an FEM proxy. The results demonstrate that the harder shot provides more beneficial material response within a tighter range.