Papers by Author: Tomotake Hirata

Abstract: The formability in friction stir and arc welded 5083 Al alloys was investigated. The elongation in friction stir welded material under uniaxial tensile test increased with the decrease in friction heat flow during friction stir welding (FSW) and the value of dome height under biaxial bulge test increased with friction heat flow. The ductility improved according to changes in FSW condition and FS-welded alloy sheet exhibited excellent formability.

Abstract: Deformation mechanism of room-temperature superplasticity in Zn-22wt%Al alloy was investigated by the direct observation during deformation. It was revealed that the dominant deformation mechanism of room-temperature superplasticity was grain boundary sliding. Also, superplastic properties and microstructure of friction stir welded Zn-22wt.%Al alloy were investigated, where Friction Stir Welding (FSW) has received a great deal of attention as a new solid-state welding technique. A sound jointing material was obtained successfully, and extremely fine and equiaxed grains were created in the stir zone. In addition, it was indicated that superplastic forming of the FSWed Zn-22wt.%Al alloy could be feasible. However, the tensile strength and elongation of the joint at room temperature were lower than that of the base material.