Effects of High Temperature Shot Peening on Surface Characteristics and Fatigue Properties of Forged AZ31 Magnesium Alloys

In this present study, the effect of high-temperature shot peening (HSP) on surface characteristics and fatigue properties of forged AZ31 magnesium alloy were investigated. HSP process were performed by peening pressure 0.2 MPa and time 6 s at peening temperature 523 K with the low-carbon steel ball. As the result, graded microstructures formed at the near surface region about 150 mu m from surface edge. It was composed by ultra fain-grained region, residual working strain region and twin region. HSP processed material was increased fatigue strength compared with non-HSP processed material. From measurement of crack propagation rate, it was found that the improvement of fatigue properties was lead of the delay of crack propagation rate in the ultra fain-grained region and the residual working strain region.