Optimization of selected casting parameters on the mechanical behaviour of Al 6061/glass powder composites.

Aluminum alloy and its composites have versatile applications and can be produced via a cost-effective stir casting technique. However, stir casting is faced with some challenges including segregation, occurrence of intermetallic phases, agglomeration, and inducement of residual stress. In view of minimizing these defects, casting should be done applying optimal parameters that will yield the desired outcome. The present study focused on the optimization of stirring parameters of temperature, speed, and time in the production of Al 6061/glass powder composite. Evaluated responses are tensile strength, compressive strength, impact strength, and hardness. The results showed that the process parameters had statistical significance on all properties at 95 % confidence level. Combined interactions of these parameters also presented significant effects on the property responses. Optimum setting for process factors as regards tensile strength were evaluated to be 600 °C, 400 rpm, and 30 min for temperature, speed, and time, respectively. For compressive strength, it is 600 °C, 500 rpm, and 30 min; for hardness, the optimum settings are 700 °C, 400 rpm, and 30 min, while in the case of impact strength, the optimum settings are 500 °C, 400 rpm, and 30 min respectively. Optimization of the combined characteristics was obtained at the optimum conditions of 500 °C, 400 rpm, and 30 min for stirring temperature, speed, and time. Moreso, the significance of the parameters on the composite in descending order is temperature, time, and speed.

Optimization studies of stir casting parameters and mechanical properties of TiO2 reinforced Al 7075 composite using response surface methodology.

Stir casting is a common metallurgical route in the casting of aluminum composites. Series of work done in this aspect considered the development of the composites with fixed stir casting parameters without applying an optimization approach. These parameters affect the microstructure and performance of the composites. The study is focused on the optimization of the stir casting parameters in the production of Al 7075 reinforced with TiO2 microparticles for performance improvement. Three stir casting parameters of stirring temperature, speed, and time were varied and optimized using the central composite design technique of the response surface method. Properties evaluated were ultimate tensile strength, hardness, impact strength, elastic modulus, and compressive strength. ANOVA results showed that the three stir casting parameters had a significant impact on the property responses. Five quadratic models were established for the properties linking them to the factors. The models were confirmed to be statistically significant at a confidence level of 95% and variations were observed to be < 5%. The interaction profile of the parameters as per response surface was analyzed. Contour plots associated with each interaction gave different ranges of stirring parameters in which each property can be maximized. Simultaneous optimization of the properties using Minitab 19 software showcased 779.3 °C, 574.2 rpm, and 22.5 min as the optimal stir casting parameters for temperature, speed and time respectively.