Modelling and optimization of parameters affecting the tensile strength and ductility of aluminum-based composite produced by FSA via RSM

One of the new methods to improve the mechanical properties of surface layers is the friction stir processing (FSP). If the FSP process is carried out with a consumable material, this new process is known as the friction stir alloying (FSA). Therefore in this research, the Al7075 surface composites by using reinforcing particles (Al2O3) were produced based on this process in accordance with the DOE approach. So, the RSM was selected as the experiment design method and variable factors such as: tool rotational speed, tool feed rate, tool shoulder diameter and size of reinforcing particles were determined as the input variables. The results of ANOVA and regression analysis of experimental data approved the accuracy of regression equations and showed that the tool feed rate, tool shoulder diameter and size of reinforcing particles with linear and second-order effects, affect on the tensile strength and ductility of the composite specimens. Also, if the tool rotational speed is set at 800 rpm, increasing the tool shoulder diameter from 9 mm to 15 mm will increase the tensile strength of the composite specimens by 17.97%. In addition, lowering the tool feed rate from 60 mm/min to 20 mm/min and reducing the size of alumina particles from 50 micron to 20 micron, will increase the ductility of composite specimens by 1.85% and 5.04%, respectively. Finally, by achieving maximum value of desirability function (0.915), the optimal condition of input variables was determined. In addition, the optimal condition has been confirmed by implementing the verification test.