Research On Squeeze Casting Technology Of High-silicon Aluminum Alloy Parts

High silicon aluminum alloy is used in manufacturing automotive engine piston, cylinder body and swashplate, because of its low coefficient of expansion, high hardness, high wearing resistance and so on. So study on squeeze casting technology of high-silicon aluminum alloy is very important to improve on the process of manufacturing in swashplate and vortex disk , reduce cost and enhance productivity .Four processes of squeeze casting technology of swashplate are analysed, and indirect squeeze casting process with one horizontal parting surface is considered the best one. The formation factors of defects such as shrinkage, air hole, slag and cold shuts were analyzed, and the measures is proposed. The results of experiments showed that the best squeeze casting processing parameters are as the intensity of pressure 120MPa, the pouring temperature 820～835℃, the pre-heat temperature of die 150±10℃. Under those parameters , the casting with smooth surface and fine microstructure can be obtained and the density of casting is up to 2.770g/cm3 .The technology of modification with Cu-10P or P-RE on high silicon aluminum alloy is researched. The results showed that there exists a good modification effect of Cu-10P on the eutectic silicon when temperature of aluminum liquid is hold between 750℃to 870℃. The size of primary silicon is below 50μm. But when the temperature is less than 700℃,the modification effect became poor. The modification effect of Cu-10P for high silicon aluminum alloy is excellent within 2 hours, and the size of primary silicon is less than 35μm. After 2 hours, the modification of Cu-10P fades quickly, and there is no modification effect after 3 hours. But The effect of P-RE compound modification can prolong to 4 hours.The optimized parameters of heat treatment named T6 are 490℃×8h+180℃×8h. Therefore, primary silicon is round and meanwhile eutectic silicon is fine, round and uniform. The tensile strength reaches to 334Mpa, which is about equal to the one of forgeable piece. The hardness is 146HBS, which is bigger than the one of forgeable piece. All properties of casting are agree with the drawing technical requirement of forgeable piece. So the squeeze casting technology of aluminum swashplate can be instead of the plastic shaping technology of swashplate, which was usually time and energy-consum and high-cost.