A novel approach for zero material loss (zero flash) and uniform cross-section during friction stir welding of dissimilar thickness Cu and Al alloys

A novel approach for getting a uniform weld cross-section and flash-free joint with the help of friction stir welding (FSW) is implemented. The influence of the tool tilt angle and rotational speed on the macrostructure, microstructure, and mechanical properties was investigated. Mechanical characterization techniques like an optical microscope, FESEM, profilometer, tensile test, bent test, and XRD analysis were used to evaluate the joint properties. A maximum tensile strength of 108.91 MPa was achieved, which led to a joint efficiency of 96.38 %. A maximum bending angle of 107˚ was achieved for samples S5 and S6. The Al/Cu mixed region in the stir zone displayed a maximum micro-hardness of 152.26 HV whereas a minimum micro-hardness of 33.57 HV was achieved in the HAZ along aluminium side. Welds prepared at a rotational speed of 540 RPM and a tool tilt angle of 4.5˚results in an almost flash-free joint.