Effect of shot peening and stress on exfoliation corrosion of 2E12-T3A1 alloy

The effect of shot peening (SP) and stress on the exfoliation corrosion behaviour of 2E12 Al alloy was studied by means of exfoliation corrosion test, metallographic analysis, scanning electron microscopy (SEM) and XRD analysis. The results show that 2E12-T3 Al alloy has a high susceptibility to exfoliation corrosion (EXCO). Tensile stress reduces the resistance to EXCO while compressive stress improves it. Appropriate SP (intensity 0.15 mmN, coverage 100%) can significantly reduces the susceptibility of 2E12-T3 Al alloy to EXCO and suppresses the formation of blisters, which may be due to the refined grain size and residual compressive stress produced by SP treatment on the surface layer. However, SP with extra intensity or coverage can not improve the resistance to EXCO due to the seriously damaged alloy surface.