Experimental and numerical analysis of aluminium alloy 7075-T7351 friction stir welds

Abstract

This paper describes a systematic series of friction stir welding experiments using aluminium alloy 7075, designed to provide validation data for a numerical model of the process. The numerical model used the commercial computational field dynamics package, FLUENT, and the trials focussed on weld temperature and torque measurements. There were several significant findings that have both practical use and are pertinent to future modelling work. First, the temperature profiles and weld quality were affected by the type of tool material. Second, in thick section welds the material reached temperatures very near to the solidus. As a consequence this limited the heat generation, so the weld power was largely independent of the rotation speed. Third, several of the welds experienced the problem of surface scaling which was exacerbated by high rotation speeds and a high plunge depth. Finally, an empirical equation for predicting the weld power was derived from the experimental power input.