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Temperature simulation of the preheating period in friction stir welding based on the finite element method

Abstract In this paper, a thermal history and distribution analysis of the preheating period of friction stir welding (FSW) of AZ31 magnesium alloy using the finite element method is presented. A moving heat source along the thickness is used to simulate the plunge movement of the pin and the heat flux generated by the friction between the pin and the workpiece is applied as volume heat. Temperature history and distributions at different plunge speeds and rotational speeds are simulated and measured to determine the appropriate preheating parameters. When a rotational speed of 600 r/min and a plunge speed of 3mm/min are used, the maximum preheating temperature can reach to about 450°C, showing that the heat generated by the pin cannot be neglected during FSW and the heat proportion is about 15 per cent of the total heat generated by the tool (including generated by the shoulder and the pin). The high temperature is in the range of the pin diameter and the maximum temperature gradient is on the boundary of the pin. The simulation temperature results corresponded well with the measured temperature during experiments.