2008 Volume 26 Issue 4 Pages 284-291
A friction stir welding process, in which a rotating tool without a probe was employed, was applied to a lap joint of aluminum plate. The thickness of aluminum plates were 0.5 mm. The new tool shapes were developed. The tops of the tool were dome shapes. In this process, the rotating tool was plunged into the aluminum plate. The tool rotating axis is vertical to the specimen surface, and then moved to the welding direction at a speed of 20 mm/s. Tool rotation speed was 18,000 rpm.
At tool plunge depths of 0.1 mm or over, it was possible to weld the two plates. At tool plunge depth of 0.1 mm, its joint was fractured at weld interface. At tool plunge depth of 0.2 mm or over, the joints were fractured at the stir zone of upper plate or the heat affected zone of lower plate. Based on the observation of the hardness profiles and the thickness change of weld area, controlling factors of the joint strength were discussed.