半固态AZ91D镁合金触变压铸充型过程的数值模拟

Numerical simulation of thixo-diecasting filling of semi-solid AZ91D alloy

以半固态AZ91D镁合金浆料的流变性能的实验研究为基础，通过曲线拟合的方法建立半固态AZ91D镁合金的表观粘度的触变模型．根据此触变模型开发了半固态AZ91D镁合金触变压铸充型过程中的表观粘度计算程序，并嵌入在Castsoft软件中，实现了半固态AZ91D镁合金触变压铸过程的流场和温度场的模拟计算．模拟结果表明：充填速度和浆料温度对半固态AZ91D镁合金浆料的充填过程有显著影响，最佳充填速度的范围为2～5m·s^-1，半固态浆料的最佳温度范围为570～580℃．

Based on the investigation of the rheological and thixotropic behavior of semi-solid AZ91D slurry, a thixotropic model describing the apparent viscosity of the slurry was established by the curve fitting method. A specific program used for calculating the apparent viscosity of AZ91D slurry during thixodiecasting was developed and embedded into the CastSoft simulating program. The flow field and the temperature field during thixo-diecasting process were simulated using the improved program. The results show that the filling speed and initial temperature of the slurry have great effects on the flow patterns of semi-solid AZ91D slurry during thix-filling, the optimum filling speed of slurry is between 2 and 5 m·s^- 1 and the optimum temperature is from 570℃ to 580℃.