以ZQS 2 0 0 0型双试棒合金热裂 线收缩仪的机械部分为基础 ,提出了一种用以测试镁合金热裂行为的新的测试方法。铸造时采用覆膜砂作为铸型材料 ,解决了镁合金在浇注过程中的燃烧问题 ;通过A/D转换 ,用微机对凝固过程中的温度、应力和收缩信号数据进行采集和进一步的处理 ,并描绘其曲线。试验测得 ,在通常凝固条件下 ,AZ91合金并不按平衡相图凝固 ,而是有共晶相析出 ;AZ91合金最容易产生热裂的温度在实际凝固结束温度 ( 4 2 4℃ )附近 Based on the mechanical part of the ZQS 2000 hot dip wire shrink tester, a new test method for testing the hot cracking behavior of magnesium alloys was proposed. In the casting process, the coated sand is used as the mold material to solve the combustion problem of magnesium alloy in the pouring process. By means of A / D conversion, the data of temperature, stress and shrinkage during the solidification process are collected and further processed by microcomputer, And draw the curve. The experimental results show that under the normal solidification conditions, the AZ91 alloy does not solidify according to the equilibrium phase diagram but has a eutectic phase precipitation. The temperature at which the AZ91 alloy is most likely to generate thermal cracking is near the actual solidification end temperature (4224C)