Influence of Welding Distance on Tool Wear in Friction Stir Welding of Ti-6Al-4V Alloy

The hot rolled plates of TC4 titanium alloys were welded by friction stir welding (FSW). The wear characterization of DZ22 superalloy tool was conducted by mass loss measurement, 3D photographic technique, SEM and EDS analysis during FSW of TC4 titanium alloy. The influence of welding distance on tool wear in FSW of TC4 alloy was investigated. The results indicate that the wear of tool is positively correlated with welding distance. Severe tool wear occurs after welding for 180 mm. The length of tool pin is shortened by 0.24 mm and the wear rate is 0.97%; the depth of tool shoulder is shortened by 0.4 mm and the wear rate is 1.73%; the mass of tool is reduced by 0.15 g and the wear rate is 0.74%. In the process of TC4 FSW, high temperature and high pressure are the main reasons for the wear of tool. Tool wear types include mechanical wear, abrasive wear, adhesion wear and oxidative wear. The wear of tool is usually the result of the interaction of these wear types. The wear products of tool will pollute the FSW joints and form defects.