Experimental study and modeling of friction stir welding process to produce optimized AA2219 butt welds for aerospace application

This article describes the effect of friction stir welding parameters on the mechanical properties and overall macrostructure features of AA2219-T87 welds. The aim is to develop a suitable combination of process parameters for producing sound friction stir welding joints of AA2219 for aerospace applications such as fabrication of space launch vehicle's propellant tank. Design of experiments approach was used to determine the influential control factors for the optimization of friction stir welding responses. The observed responses, such as the ultimate tensile strength and percentage of elongation of welds, were compared with the specified requirements for the said application. Weld cross-sectional area and the grain size in various zones of the weld were also recorded. A full-factorial experimental design was conducted to obtain the weld responses. Analysis of variance, interaction effects and desirability function-based techniques were used to determine the significant welding parameters and to set the optimal level for each control factor. Regression equations were developed to predict output characteristics of welds. The experimental and the predicted values were in a good agreement. Response surface modeling was carried out to identify the combination of process parameters to optimize the responses. The modeling methodology adopted and the optimization technique used in the present investigation are observed to be adequate for producing sound AA2219-T87 welds to meet the specification requirements of the intended aerospace application.