Automation of friction stir welding process to join aluminum matrix composites by optimization

The objective of this research work is to identify a set of friction stir welding parameters to join aluminum matrix composites which will give higher tensile strength, ductility and wear resistance. AA6061/ZrB₂ composites were produced by the in situ reaction of K₂ZrF₆ and KBF₄ with molten aluminum. Plates of 6 mm thickness were prepared from castings and joined using friction stir welding. Four factors, five levels central composite rotatable design was used to minimize the number of experiments. The factors considered were tool rotational speed, welding speed, axial force and weight percentage of ZrB₂. Mathematical models were developed to predict tensile strength, elongation and wear rate. The developed mathematical models were optimized using generalized reduced gradient method to obtain higher tensile strength, ductility and wear resistance. The optimized parameters can be fed into the friction stir welding machine to automate the process to achieve desirable joint properties.