Modelling of entire friction stir welding process by explicit finite element method

A coupled thermomechanical three-dimensional finite element model was developed for friction stir welding in the ABAQUS environment using Johnson–Cook material law and Johnson–Cook failure model. The temperature evolution during the plunge, dwell and moving stages of a friction stir welded 7050 aluminium alloy and the effect of heat conduction by the back plate were investigated. Results show that the temperature almost symmetrically distributes across the plate cross-section, and the temperature contour in the weld nugget zone presents a V type shape after the plunge stage. In the dwell stage, the frictional heat conducts around to preheat the plate. While in the moving stage, the heat gradually accumulates until a quasi-stable temperature field is formed. Moreover, it is shown that the heat conduction through the back plate has a significant effect on the temperature field. With the increasing heat convective coefficient of the back plate, the temperature field remarkably shrinks.