抄録
Rolled magnesium (Mg) alloy AZ31 and cold-rolled steel SPCC sheets were welded by a friction stir welding (FSSW) using a scroll grooved tool without probe. Tensile shear fatigue tests using the welded joint were performed in order to investigate the fatigue behavior. The static tensile shear strength of Mg-SPCC dissimilar joint was 2.5kN, which was nearly the same as that of Mg-Mg similar joint. The fatigue strength of Mg-SPCC joint was also the same as that of Mg-Mg joint and the fatigue limit at 10^7 cycles was a little higher, which indicates that FSSW is effective for welding the dissimilar metals of magnesium alloy and steel. In the Mg-SPCC joint, the shear fracture occurred at the welded boundary while in the Mg-Mg joint, cracks propagated not along the boundary but through the base metal.
