Abstract: Based on the analysis of the balance of heat generating and dispersing after the friction stir welding (FSW) procedure being steady, the numeric model of welding temperature is established. It can be seen that a lot of influencing factors on the temperature are enclosed, such as the physical natures of the welded material and the material of stir tool, the friction coefficient between the two sliding materials, the dimensions of the stir tool, the welding parameters, the pressure on the surface and on the side face of welded plate etc. The relationships between some factors are complex, being affected by each other. The principal factors are rotation speed of stir tool, friction coefficient between the stir tool and the workpiece, the pressure on the surface and on the side face of welded plate. The validity of the model is testified by FSW on PVC plate. The calculated welding temperature is considerably identical with the measured one provided some parameter values are taken in a suitable range.

Key words: Friction stir welding, Welding temperature Numeric model