Effect of probe and shoulder rotation speed of adjustable Friction Stir Welding for dissimilar lap joint

The Friction Stir Welding is well known as non-melting joining process. But the phenomena in the process are not well understood yet because measurements of fluid flow and stress profile during the process are very difficult. A lot of numerical models for FSW also have been developed to understand the process. A particle method is applied to FSW simulation and a model for dissimilar lap joint has been developed by authors. This model can qualitatively express the plastic flow around the tool. The plastic flow and temperature distribution at the interface of two materials is very important for joint quality because the temperature history has large affected to the intermetallic compound formation. But it is difficult to control the temperature history of material interface by normal FSW. Adjustable FSW (Rotating speeds of probe and shoulder are different.) is used to dissimilar lap joint to control the temperature history of interface. In this study, adjustable FSW model has been developed. The model is applied to dissimilar lap joint (aluminum and SUS). The material flow and temperature profile around the tool is visualized. The effect of probe and shoulder rotating speed on the interface temperature and the interface material flow is evaluated and controlling the size of the material flow area by the motion of the tool is also discussed.