Modelling of the effect of process parameters on tensile strength of friction stir welded aluminium alloy joints

Friction stir welding (FSW) process is a promising solid-state joining process with the potential to join low-melting point material, particularly, aluminium alloy. The most attractive reason for joining aluminium alloy with this process is the avoidance of the solidification defects formed by conventional fusion welding processes. In this article, an attempt has been made to develop an empirical relationship between FSW variables and tensile strength. Central composite rotatable design was used by considering four factor and five levels, which enables to quantify the direct and interactive effect of four numeric factors, that is, tool rotational speed, welding speed, axial force, and tapered pin diameter on the tensile strength. The developed relationship is useful for prediction of tensile strength in friction stir welded AA6082 aluminium alloy joints at 95% confidence level. It will also be helpful for selection of process variable to obtain desired strength of the joint. Furthermore, the optimized capabilities in design-expert software were used to numerically optimize the input parameters. At the optimal parameters, three experiments were conducted to compare the predicted value of tensile strength with the experimental value.