Deformation of dissimilarly oriented aluminum sheets welded by friction stir welding under uniaxial tension perpendicular to the weld bead

This study investigates the deformation behavior of dissimilarly oriented tailor-welded blanks (D-TWBs) under uniaxial tension perpendicular to the weld beads. The D-TWBs were fabricated by friction stir welding of 1-mm-thick aluminum sheets in the rolling (0 degrees), 45 degrees and transverse (90 degrees) directions. This study examined the mecha-nism of uniaxial tensile deformation of the aluminum TWBs by analyzing the microstructure and flow curve. In the D-TWBs, a material with a lower deformation resistance was elongated more than twice larger as much as the other material, and fracture occurred in this material. The total elongation became smaller than that for the raw materials by 0.15-0.35 owing to a decrease in the local elongation after necking. This resulted from the plane strain deformation near the weld bead immediately before fracture. Texture rotation occurred almost in-plane in the process-affected zone of the D-TWBs, and the method of rotation differed between materials with different orientations. However, despite the differences in texture, the study suggests that deformation was not strongly affected. The F values and n values, which were evaluated from partial deformation, did not vary significantly from those of the raw materials, but a decrease of approximately 10 % was observed at the maximum. Similarly, the r values of the D-TWBs also did not vary significantly in the original orientation with low a r value; however, in the orientation with a large value, it decreased approximately 0.2 at the maximum. Finally, the study also examined mechanisms of deformation and fracture in the D-TWBs.