Analysis of Variance of Dissimilar Cu-Al Alloy Friction Stir Welded Joints with Different Offset Conditions

In this investigation, dissimilar material AA6061-T6 and Cu B370 were joined by friction stir welding (FSW). This paper presents a feasibility study of FSW to join Al-alloy and Cu-alloy. The experiment was conducted using general full factorial design by varying the tool rotation speed, weld speed, and probe offset, and by keeping the plunge depth constant. In this research work, a statistical model was established to build a connection between the process variables and outcomes-yield strength (YS), ultimate tensile strength (UTS) and % elongation (% E). Statistical tools such as analysis of variance and scatter diagrams were employed to evaluate the suitability of the models. In addition, the impacts of the process variables on the tensile properties were investigated. From the experimental results, it can be concluded that (i) an excellent weld joint could be obtained by keeping the softer Al plate at the retreating side with a probe offset of 2.0 mm towards the softer material, and (ii) maximum tensile properties were obtained at a higher tool-rotation speed, weld speed, and with a probe offset of 2.0 mm. Further, the fractured tensile specimens were investigated using a scanning electron microscope (SEM). From the analyses, it was noted that, during the tensile test, the weld joint failed with a brittle-ductile mixed fracture mode.