The Effects of Material Flow on Texture Evolution and Tensile Fracture Behaviors of Friction Stir Welded AZ40M/AZ61A Dissimilar Mg Alloys Joint

ABSTRACT This study aims to elucidate the effects of material flow on texture evolution and tensile fracture behaviors of friction stir welding (FSW) AZ40M/AZ61A dissimilar Mg alloys joint. The stirring pin mainly affects the material flow between the middle and top of the stir zone (SZ). The SZ presented fine and equiaxed grains because of dynamic recrystallization (DRX), and the average grain size is 19.9 μm. The SZ center presented the strong typical basal texture with a texture intensity of about 63.333 times random distribution that deteriorates the joint mechanical properties. The yield strength of the dissimilar Mg alloy welded joint is 172 MPa, which is about 75% of the base metals. The AZ40M and SZ edge has the lowest hardness of 54.8 HV, which is the softened area of the joint, resulting in crack propagation and fracture during the tensile process. The tensile crack was initiated at the edge of the SZ near the AS with the lowest hardness and propagated along the SZ center. The crack path depended on the “onion‐ring structure” and the second phase.