Numerical analysis of heat generation and temperature field in reverse dual-rotation friction stir welding

A 3D model is developed for numerical analysis for heat generation, temperature field, and material flow in reverse dual-rotation friction stir welding (RDR-FSW) process. The reverse rotation of the assisted shoulder and the tool pin is considered to determine the heat generation rate. Friction heat, plastic deformation heat, and their partition coefficients are analyzed. Due to the tool pin and assisted shoulder being separated and reversely rotated independently, the temperature difference between the advancing and retreating sides is weakened. The reverse material flow is beneficial to the uniformity of both the temperature and microstructure at the advancing and retreating sides. The calculated temperature profiles agree well with the corresponding experimentally measured values.