Study On Semi-solid Billets Prepared By AZ91D Magnesium Alloy Chips

In the conventional die-casting magnesium alloy production practice, the melt of magnesium and oxygen have a strong affinity, but also combined with a high vapor pressure of magnesium as control of the security problems in production, so on the need to develop new molding process to resolve these problems. Semi-solid forming of magnesium alloy which can be a good solution to these problems. In this percent paper, semi-solid billets of AZ91D magnesium alloy prepared by hot pressing and then isothermal heat treatment, and researched the fluxion property of thixo-process with AZ91D magnesium alloys by experiment.The optimum parameter of isothermal heat treatment was investigated. It analyzed the effect of semi-solid temperature, holding time and differ place on microstructure of semi-solid blank. Semi-solid isothermal temperature of 570℃, the time the grain spheroidization basically completed, Particles round, uniform particle size distribution, liquid higher rate of particle aggregation phenomenon is very less, its viscosity is very small, is conducive to semi-solid forming. Semi-solid isothermal time was 30min, the grain at this time basically grew up completely, the ball of the grain refining effects were good, solid-phase fraction lower. Therefore, isothermal heat treatment the optimum parameter is semi-solid isothermal temperature of 570℃, semi-solid isothermal time of 30min.At the optimum parameters of isothermal heat treatment, the sample location of its center heart department organized by the ministry of the rate of the ball the best, a higher rate of liquid, particles round, uniform particle size distribution.The use of isothermal heat treatment results of the experiment, Studied the semi-solid liquidity test the optimum, analyzed the effect of fluxion property on different holding time mechanical properties, and disclosed the fluxion mechanics of AZ91D magnesium alloys in semi-solid state. when 570℃semi- solid isothermal 30min, AZ91D magnesium alloy semi-solid slurry flow the best, magnesium alloy semi-solid slurry has filled the entire cavity, and the semi-solid magnesium alloy can be maintained, and can be further refined. The results indicate that: because the chips of AZ91D magnesium alloy oxidation after hot pressing and then isothermal heat treatment,and in the process of hot pressing, high oxygenous of the thixo-processing drip molding. The odds of press, result in the interface of chips combine insufficiency, the tension property of thixo-processing drip molding as much as convention processing drip moldings'.