Numerical studies on the effect of transverse speed in friction stir welding

The effect of transverse speed on friction stir welding is analyzed in detail for the controlling of this parameter by using a fully coupled thermo-mechanical model. When the transverse speed is higher, the stirring effect of the welding tool becomes weaker, which is the reason for the occurrence of weld flaw. The material particles on the top surface at the advancing side are transported by the shoulder to the retreating side and piles up on the border of the nugget zone at the retreating side. This is the reason for the formation of weld fash in the friction stir welding process. Friction instead of plastic deformation takes the main contribution to the temperature rise in the friction stir welding process. When the transverse speed is increased, the contribution of the plastic deformation to the temperature rise is increased. But the variation of the transverse speed does not significantly affect the power needed for FSW. (C) 2008 Elsevier Ltd. All rights reserved.