The continuing quest for aluminum castings with fewer defects has aroused the interest in rheological high-pressure die casting (RHPDC). A new machine, stirring integrated transfer-heat (SIT) device, based on the mechanical stirring and enhanced cooling for semisolid slurry preparation was proposed to produce the thin-walled communication shell part by RHPDC process. The influence of SIT process characteristics on the microstructure was studied. The microstructure of SIT-RHPDC shell part in different locations was investigated. Combined with simulation, the flow characteristics and the temperature field change in the melt under the stirring-only process and different stirring with internal water-cooling conditions were studied to get a better understanding of the nucleation, grain growth and solidification behavior. Under the dual action of agitation and heat dissipation in SIT device, the fluid convection has changed the temperature field of the melt significantly. The temperature field of the melt becomes relatively uniform from a great temperature gradient and the continuous cooling rate is increased to 5 °C/s. In the same time, the slurry has a greater supercooling degree, and flows more evenly in the filling process. The experimental results indicate that compared with microstructure of an HPDC component, the microstructure at different locations of SIT-RHPDC part is composed of refined rosiness and nearly spherical particles.

中文翻译：

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水冷却搅拌传热过程中半固态铝合金铸件的组织和模拟

对具有更少缺陷的铝铸件的不断追求引起了对流变高压压铸件（RHPDC）的关注。提出了一种基于机械搅拌和强化冷却技术的半固态浆料制备搅拌综合传热（SIT）装置，以RHPDC工艺生产薄壁通讯壳零件。研究了SIT工艺特性对显微组织的影响。研究了SIT-RHPDC壳部件在不同位置的微观结构。与模拟相结合，研究了在仅搅拌过程以及内部水冷却条件下不同搅拌条件下熔体的流动特性和温度场变化，以更好地理解成核，晶粒长大和凝固行为。在SIT设备的搅拌和散热双重作用下，流体对流显着改变了熔体的温度场。熔体的温度场从较大的温度梯度开始变得相对均匀，并且连续冷却速率提高到5°C / s。同时，浆料具有较高的过冷度，并且在填充过程中流动更均匀。实验结果表明，与HPDC部件的微观结构相比，SIT-RHPDC部件不同位置的微观结构由精制的玫瑰色和接近球形的颗粒组成。熔体的温度场从较大的温度梯度开始变得相对均匀，并且连续冷却速率提高到5°C / s。同时，浆料具有较高的过冷度，并且在填充过程中流动更均匀。实验结果表明，与HPDC部件的微观结构相比，SIT-RHPDC部件不同位置的微观结构由精制的玫瑰色和接近球形的颗粒组成。熔体的温度场从较大的温度梯度开始变得相对均匀，并且连续冷却速率提高到5°C / s。同时，浆料具有较高的过冷度，并且在填充过程中流动更均匀。实验结果表明，与HPDC部件的微观结构相比，SIT-RHPDC部件不同位置的微观结构由精制的玫瑰红和接近球形的颗粒组成。