Abstract
Rotating bending fatigue tests on shot-peening (SP) treated AC4CH aluminum alloy were carried out in order to investigate the effect of SP treatment on the high cycle fatigue properties. As comparing fatigue property of the SP-treated material with fatigue properties of non-peened material, hot isostatic pressure (HIP) treated material and semi-liquid (SL) die casting material, the following conclusions were obtained. (1) Although the fatigue property of SP-treated material is most excellent in all materials, they are a few differences as compared with HIP-treated material and SL material. (2) The fatigue life property of AC4CH alloys is significantly affected by fatigue crack initiation behavior. The reason why the SP-treated material has longer fatigue life than that of other material is that it has no cast defects near the surface by the effect of SP treatment. Moreover, the fine granular microstructure near the surface caused by SP treatment affects fatigue life since this fine granular structure prevents generation of the slip in crystal grain, which causes the surface fatigue crack initiation.
