Evaluation of heat input during friction stir welding of aluminium alloys

Heat input is one of the key parameters governing the quality and service properties of friction stir welds. By using a calorimetric technique, the heat inputs generated during the friction stir welding of the aluminium alloys, 1100 and 5083, were measured over a wide range of welding parameters. An empirical equation to estimate the heat input using the welding parameters was established based on a multiple regression analysis of the results. The effect of the heat input on the final grain size of the stir zone was also investigated by the electron backscatter diffraction method. The quantitative relationships between the input variables, heat inputs, and final grain sizes in the stir zone were derived.