Impact of Tool Pin Configuration on Weld Formation of Non-thinning Friction Stir Welded Aluminum Alloy

Abstract

Non-thinning friction stir welding (NT-FSW) is the critical technique to guarantee the accurately shaped welding of structures in rail industries. In order to illuminate the affecting characteristic of tool pin configuration on NT-FSW behavior and thus to provide technological guidance for the high-quality applications of the process, the welding tools with smooth pin, smooth-flattened pin and threaded-flattened pin are utilized to conducted NT-FSW experiments in the present paper, and the weld morphology and the defect distribution are comparatively investigated on aluminum alloy welds. The results indicate that for NT-FSW process the thread feature is the most important to the tool pin for the formation of defect-free joints. The flattened tool pin widens the softening region and improves the softening levels at the weld top. By contrast, the thread feature can control the local softening occurring in FSW, which narrows the softening region width.