Cold-Rolled Mg-14 mass%Li-1 mass%Al Alloy and Its Friction Stir Welding

The feasibility of friction stir welding (FSW) for cold worked Mg-14 mass%Li-1 mass%Al alloy was investigated. The alloy melted and cast into ingots under pressurized argon gas atmosphere. Slabs prepared from homogenized ingots, then cold-rolled up to 0.5 mm thickness. The density of this alloy is 1.326 g/cm3 and its ultimate tensile strength is from 180 to 294 MPa according to the reduction ratio of rolling. The cold rolled plates of 2 mm thickness were butted and jointed by FSW with various tool rotation and traveling speeds. It was found that the sound joints can be made at specific conditions apart from that of AZ31 alloy. Measurement of cross sectional hardness profile revealed slight higher hardness of stir zone than that of work-hardened base metal. The hcp peaks clearly appeared at XRD profiles from stir zones.