铝合金枝晶生长的数值模拟

NUMERICAL SIMULATION OF DENDRITE GROWTH OF ALUMINUM ALLOY

提出一种新的模拟铝合金枝晶生长的随机性方法,建立了简化的枝晶形状的物理与数学模型,并提出了一种形状函数来描述晶粒的外部轮廓,基于简化的晶粒形状,采用坐标变换技术来描述过冷液相中晶粒的生长过程及其对周围节点的捕获过程.根据上述思想,开发了等轴晶生长的模拟程序,并进行了二维计算.为了验证模拟结果,浇注了金属型和砂型试样.模拟结果表明,金属型铸造晶粒尺寸较小,砂型铸造的较大.模拟结果与金相观察结果相符.

Microstructure modeling of aluminum alloy casting has been carried out by using a new stochastic modeling method coupled with macro heat transfer calculation. The physical model and mathematical model for the simplified dendrite shape were established, in which a shape function was presented to describe the dendrite shape contour. On the basis of the simplified grain shape, a coordinate transformation method was used to describe the equiaxed grain growth in the undercooled melts and the node capturing during the further growth of a grain. According to the above model, the microstructure simulation scheme was developed to model the grain formation. Two-dimensional calculations were performed to simulate the evolution of equiaxed dendritic morphologies. In order to verify the modeling results, the castings were cast in sand mold and metal mold. Simulation results show that grain size is smaller for metal mold casting, but larger for sand mold casting, which is in good agreement with the experimental results.