Design of experiment study on hardness variations in friction stir welding of AM60 Mg alloy

Abstract

Identification of process parameters, their effects and contributions to the outcomes of the system using experimental approach could be a daunting, time consuming, and costly course. Using proper statistical methods, i.e., Taguchi method, could significantly reduce the number of required experiments and statistical significance of the parameter can be identified. Friction stir welding is one of those welding techniques with many parameters which have different effects on the quality of the welds. In friction stir welding the tool rotational speed (RPM) and transverse speed (mm/min) influence the strength (i.e., hardness distribution) of the stirred zone. In this study, these two factors are investigated to determine the effect they will have on the hardness in the stirred zone of the friction stir welds and how the two factors are related to one another for as-cast magnesium alloy AM60 with nominal chemical composition of Mg- (5.5–6.5) Al- (0.24–0.6) Mn- 0.22Zn–0.1Si. Experimental data was taken at three different tool rotational speeds and three different transverse speeds. The data obtained was then analyzed using a 32 factorial design to find the contribution of these parameters. It was determined that both tool rotational speed and transverse speed possess significant effects on the stir zone hardness. Also, the interactions between the two factors were statistically assessed. Keywords: AM60 Mg alloy, Design of experiment (DOE), Statistical method, Friction stir welding