Numerical Simulation of the Effect of Shoulder Rotation on the Tensile Strength of FSW Dissimilar Joints of Aluminum Alloy

Abstract

Dissimilar weld metal joints such as aluminum alloys 5083 and 6061-T6 are mostly found in the application of aircraft, railroad structures, ships, bridges, and oil platforms and building structures. However, dissimilar welding metal is relatively more difficult due to metallurgical differences and the thermophysical properties of two different materials. The purpose of this study is to study the effect of shoulder rotation variations on the Friction Stir Welding (FSW) process through numerical simulations on the mechanical properties of dissimilar weld joints between two series of aluminum alloys, and there are 5083 and 6061-T6. The FSW welding simulation process is conducted by butt joints type on 300 x 100 x 3 mm of both aluminum plates with weld distance is 300 mm. Shoulder rotation variations are carried out for this process include 1,200, 1,400 and 1,600 rpm. Results show maximum temperature distributions are 467 oC for 1,200 rpm, 499 °C for 1,400 rpm and 527 °C for 1,600 rpm, respectively. Maximum temperatures appear close to the liquid temperature of Al-6061-T6 and Al 5083 base metals, which is about 600 °C. Physical and mechanical analysis at 1,200 rpm (the rotation parameter) can be seen as the coarse weld beads on the microstructure, and the weld joint is still weak. The physical properties observed that coarse weld beads on microstructures, the tensile strength obtained 138 MPa at 1,200 rpm (the rotation parameter). The maximum hardness test occurred 47.98 (Kg/mm2 in averages) at 1,400 rpm. The tensile strength of the dissimilar FSW process is 151 MPa occurred at 1,600 rpm of shoulder rotation speed. While the fracture position occurs in the nugget weld area for all parameters and corresponds with the result of hardness tests, it shows that low hardness value for the whole weld area for all parameters.