Anisotropic Torsion Strength of Round Bar A6061 Friction Weld Joint with Various Upset Pressures

Abstract

This paper revealed anisotropic torsion strength of round bar aluminium alloys A6061 friction weld joint affected by upset force. Round bar A6061 was used for friction welding specimen with two different geometries which were the specimen with flat friction surface (without chamfer angle) and the specimen with chamfer angle of 15 degree. Continuous Drive Friction welding (CDFW) was done by applying initial friction pressure of 39 MPa and upset pressure variation of 39 MPa, 79 MPa and 119 MPa. Torsion test was done according to ASTM standard in which torsion direction was applied in the same and in the opposite direction of friction welding revolution. It was found that the higher upset pressure can give the higher torsion strength of the specimen. The specimen without chamfer angle that applied by 119 MPa of upset pressure has the maximum torsion strength of 165 MPa, with torsion loading direction is the opposite to revolution direction of friction welding process. The anisotropy of torsion strength was found in the specimen, where the torsion strength of the specimen in the opposite direction of friction welding revolution is higher than in that of specimen with the same direction as revolution direction of friction welding process. The maximum difference between torsion strength in the opposite direction of revolution of friction welding and that of specimen with the same direction of friction welding revolution is around 6% that occurred in the specimen without chamfer angle and applied by the highest upset pressure. It was thought that interaction between torsion loading direction and the microstructure of the weld joint as the result of plastic deformation due to upset pressure and revolution during CDFW process affects the existence of the anisotropic torsion strength.