Abstract: The surface plastic deformation strengthening behaviours of magnesium alloy of ZM1 are studied. The results show that there is an excellent surface plastic deformation strengthening effect for magnesium alloy of ZM1 with hexagonal close-packed structure, the increments of the notch fatigue limit is about 157%～212% after surface rolling and is greatly above the smooth fatigue limit of non-rolling. The high notch fatigue strength can provide extra ample strength for parts, and notch fatigue limit that exceeded the smooth fatigue limit can also provide a possibility for equel strength design of parts. During surface rolling, the plastic deformation can be carried out in the surface layer of specimens by way of both slip and twin, with increasing the dislocation density and the introducing the high residual compressive stresses. The improvement of notch fatigue limit is mainly attributed to the high residual compressive stresses. Based on this, a new strengthening viewpoint of residual stress is proposed, which the residual compressive stresses play a dominant role in the fatigue strength for surface plastic deformation parts.

Key words: Fatigue strength, Magnesium alloy, Plastic deformation, Residual stress