Optimization of AZ91 friction stir welding parameters using Taguchi method

In this research, AZ91 alloy sheets were joined using friction stir welding and the process parameters were optimized using Taguchi L-27 orthogonal design of experiments. The pin shape, rotational speed, traverse speed, shoulder diameter, penetration depth, pin diameter, tool tilt angle, and shoulder concave angle were the parameters taken into consideration. The optimum process parameters were determined with respect to grain size, hardness, yield strength, and ultimate tensile strength of the joint. The predicted optimum values for output parameters were confirmed by conducting the confirmation test using optimum parameters. Analysis of variance shows that the traverse speed is the most dominant factor in determining the joint mechanical properties, hardness, and grain size; and shoulder diameter, tool pin shape, and rotational speed are the 2nd to 4th effective parameters.