The Effect of Pouring Temperature, Mechanical Vibration and Partial ‎Remelting on Microstructure and Mechanical Properties of Al-A390 Alloy

In the current research, the effect pouring temperature, mechanical vibration of mold, mold temperature and partial remelting on microstructure and mechanical properties of hypereutectic Al-Si alloy was investigated. For designing of experiment, Taguchi method is used. Signal to noise ratio and analysis of variance were used for finding optimized parameters and contribution percent of parameters on amount of output character. After finding the optimized parameters for producing primary billet, partial remelting process is carried out in three temperatures of 540, 555 and 565°C and five holding times of 5, 30, 60, 90 and 120 min. Scanning electron microscope and optical microscope have been used to evaluate the microstructure. The average particle diameter, distribution factor and sphericity of primary Si and Eutectic Si were analyzed by image analysis software. Result of analysis showed that sample with pouring temperature of 750°C, mold temperature of 350°C and frequency of vibration of 60Hz, had maximum hardness and tensile strength. On the other hand, the result of microstructure showed partial remelting process led to increase the sphericity and decrease of average particle diameter of Eutectic Si, but no slight effect on the size of primary Si.