A new calculation method of viscoplastic heat production generated by plastic flow of friction stir welding process

Friction stir welding (FSW) is a solid phase welding method. The weld forming and welding quality are related to the heat production generated by plastic flow during FSW process. Therefore, it is of great importance to measure the viscoplastic heat production during FSW process. In this paper, firstly, taking the welding system during quasi-steady state welding stage as a rotary viscosity measuring meter, the relationship between viscous moment and viscosity is deduced. Secondly, the analysis model for plastic flow around welding pin in FSW process is established by applying the principle of fluid dynamics. The relationship between the temperature gradient on the surface of welding pin, the rotation rate of the FSW machine and viscous torque is obtained. Lastly, a new calculation method for viscoplastic heat production in FSW process is proposed with the help of numerical simulation. To verify the validity of the new calculation method, several groups of friction stir welding experiments are carried on.