Optimization of processing parameters for rheo-casting AZ91D magnesium alloy

A design of experiment technique was used to optimize the microstructure of the AZ91D alloy produced by rheo-casting. The experimental design consists of four parameters (pouring temperature, shearing temperature, shearing time and shearing rate) with three levels. The grain size and shape factor measurements of primary α-Mg particles were conducted to determine the microstructure. The contribution of each parameter shows that pouring temperature is the most significant parameter affecting the grain size, and the shape factor highly depends on the shearing temperature. The optimized rheo-casting processing parameters are 650 °C for pouring temperature, 585 °C for shearing temperature, 40 s for shearing time, and 600 r/min for shearing rate. Under the optimized processing parameters, the average grain size is 28.53 μm, and the shape factor is 0.591.