This report describes the simulation of friction torque and temperature at welded interface in 1st phase of friction welding. The simulation models at the initial friction part and the seizure part were made from the observed joining phenomena at the 1st phase. In actual simulation, the real contact area and the thermal stress at welded interface in initial friction part, and the seizure temperature and the relative speed of welded interface in seizure part were considered. The calculation of the friction torque and the temperature at welded interface were carry out in compound of the friction pressure, the relative speed and the flow stress at base metal. The calculated values about friction torque, initial torque and elapsed time for initial torque were approximately consistent the experimental values. The calculated values about temperature at welded interface of center portion were higher than that of periphery (outer surface) portion at the time that the friction torque reached to the initial torque. As a conclusion, the friction torque and the temperature at welded interface could be simulated by the made simulation model in 1st phase of friction welding.
