Experimental Study And Numerical Simulation Of Semi-solid7A09Aluminum Alloy Billet Prepared By Rotate Casting Method

In this paper, semi-solid7A09aluminum alloy billet is prepared successfully by rotation pipe casting method. By means of orthogonal experiment, the main factors’effects on the microstructure are studied, including pouring temperature, rotation speed of steel pipe and preheating temperature of mould. In order to reveal how the factors affect the billet, the simulation software ProCAST is used for building the experiment model.Making use of self-developed equipment, semi-solid7A09aluminum alloy billet is prepared by rotation pipe casting method. The results show that pouring temperature and the rotation speed of steel pipe have a great impact on the experiment results, and the preheating of mould has a small impact. With average diameter of grain as the criterion, semi-solid billet of fine and uniform-distributed grain can be achieved at a low pouring temperature and the rotation speed. When pouring temperature is too high, different kinds of shapes of coarse grains are achieved. When pouring temperature is too low, the liquidity of aluminum alloy will reduce, which possibly results in pipe blockage. The low rotation speed is great to the formation of nuclei and increases effect of agitation. However, when the rotation speed of steel pipe is too high, the cooling capacity of pipe will increase, which is against to obtaining fine semi-solid microstructure.Experiments show that the uniform grains can be obtained when the pouring temperature, rotation speed of steel pipe, and preheating temperature of mould have a great match relationship, and the average diameter of grain is about100μm. The optimum range parameters of experiments of pouring temperatures are about660～680℃, and the rotation speeds are about0-150r/min, and the preheating temperatures of mould are200～250℃The corresponding experiment model is established by means of the CAE software of ProCAST, and the change of flow field and temperature field can be observed by the simulation. The simulation emphasis is to study experiment parameters’influence on the solidification time of the billet center. The results show that the preheating temperature of mould has the greatest impact on solidification time, the pouring temperature has the great impact on solidification time, and the rotation speed of steel pipe has a little impact on solidification time. The high pouring temperature and preheating temperature of mould will lead to the extension of the solidification time, which is against to grain refining. The experiment and simulation results show that the low pouring temperature and preheating temperature of mould are benefited to obtain high quality semi-solid billet.