Visualisation and numerical simulation of material flow behaviour during high-speed FSW process of 2024 aluminium alloy thin plate.

Material flow during friction stir welding of ultra-thin 2024 aluminium alloy plates was investigated by using copper powder as marker material. Based on the visualised experiment and numerical computation of material flow produced in the research, the effect of rotational speed on material flow was revealed. In high rotational speed FSW process, flow distance along welding direction of plastic metal on both sides and transverse flow distance to the weld centre line on the retreating side were shorter; however, a larger flow velocity was shown. The flow velocity of plastic metal decreased with the increasing of distance from the weld centre, while it increased with the increasing of rotational speed under a constant rotational speed/welding speed ratio. Maximum and minimum values of the flow velocity of plastic metal were located at the intersection of triple spiral groove of shoulder and both sides of its outer diameter edge, respectively. [ABSTRACT FROM AUTHOR]