行波磁场作用下空心管坯的两相凝固数值模拟

利用等轴球晶两相凝固模型计算了行波磁场作用下空心管坯的凝固过程.分析了施加不同强度的行波磁场时,Sn-3.5%Pb管坯凝固过程的温度梯度、冷却速率、溶质浓度分布以及晶粒大小的变化情况.结果表明:金属液在行波磁场的作用下产生纵截面上的大环流,随着搅拌速度的加大,金属液凝固过程的冷却速率逐渐降低,熔体内的温度梯度减小,使管坯内部的晶粒得到细化,改善了铸坯凝固组织,但是强制流动导致管坯内产生宏观偏析,且搅拌速度越大,宏观偏析越明显,因此,在生产过程中应该严格控制搅拌速度的大小.

Numerical Simulation of two-phase Solidification Process of

The two-phase model of globular equiaxed grain solidification has been used to compute the solidification process of Sn-3.5%Pb hollow billet under traveling magnetic field. The temperature gradient, cooling rate, solute concentration distribution and grain size are studied under different stirring velocities. The results show that the traveling magnetic field can result in a global circulation flow in the molten metal, the temperature field is uniformed and the grain size is refined, which improve the solidification structure of hollow billet. However, the macro segregation is produced in the hollow billet by the forced flow. So, the stirring velocity should be controlled carefully during the casting of hollow billets.