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In this paper, the effects of squeeze casting parameters on the wear behavior of A390 aluminum alloy were investigated. For this purpose, the experiment was designed according to L9 Taguchi array that the squeeze pressure (60, 90 and 120 MPa), the superheats of liquid metal (50, 100 and 150 °C) and the die preheating temperature (200, 250 and 300 °C) were selected as the independent variables at three levels. On the contrary, the microstructure characteristics, the weight loss of specimen after wear test and friction coefficient were examined as dependent variables. The microstructural characterizations were also performed using optical microscopy equipped with image analyzer and SEM equipped with EDS. The squeeze casting was performed with a 20-ton hydraulic press in a cylindrical shape. According to the results, the increase in squeezing pressure from 60 to 120 MPa within the tested range leads to a decrease in primary silicon area by 48% and a decrease in silicon eutectic by 44.4%; however, applied pressure did not have any significant effects on morphology of phases. The wear tests were carried out using a computer-controlled pin on disk wear test machine in ambient temperature.

Effects of squeeze casting (SQC) parameters, including squeezing pressure, superheats of liquid metal and die preheating temperature on microstructure characteristics and mechanical properties of A390 aluminum alloy, were evaluated using L9 design based on Taguchi method. Squeeze casting was performed by a 25-ton hydraulic press, and all of the parameters were evaluated at 3 different levels: the squeezing pressure was at 60, 90 and 120 MPa, the superheat of the liquid metal was at 50, 100 and 150 °C and the die preheating temperature was at 200, 250 and 300 °C. The microstructure characterization was also performed using optical microscopy image analysis and scanning electron microscope (SEM). Tensile and Brinell test methods were applied for measuring ultimate tensile strength, yield strength, elongation and hardness. The results showed that the SQC process modified cast microstructure and improved mechanical properties of the alloy. In addition, the variations of the SQC parameters, specially the squeezing pressure, have significant effects on the size and volume fractions of the primary silicon, eutectic cells and the mechanical properties. According to the results, increase in squeezing pressure from 60 to 120 MPa within the tested range leads to primary silicon area decrease by 48% and silicon eutectic decrease by 44.4%; however, applied pressure did not have any significant effects on morphology of phases. On the other hand, superheating over 100 °C and die preheating at 200 °C had significant effects on the final result. It is clearly observed that rising pressure to 90 MPa consequently increases the tensile strength, elongation and hardness. But increasing the pressure to over 90 MPa did not have any significant effects on the final result.

The as-casr microstructure of HK heat resistant steel produced by the investment casting process has been investigated. The pouring temperature and cooling method effects on the austenite grain size and shape, segregation of alloying elements and formation of eutectic carbides have been evaluated herein. Microscopic studies have shown tliat the microstructure of the steel consists of dendritic austenite with carbides in the grain boundaries and dendritic arm spaces. Decreasing the pouring temperature converts large columnar grains to small equiaxed grains and prevents the large eutectic carbides in the grain and dendritic boundaries. Also, increasing the cooling rate can decrease the formation of grain boundary carbides.