【摘要】 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℃ )附近更多还原

【Abstract】 Based on the mechanical parts assembly of the twin bar tester of hot tearing linear contraction for alloy, a new way to testing hot tearing behavior of Mg alloy was developed. In the system, resin precoated sand was used as molding material to solve the combustion of Mg alloy during pouring process. The signal data of temperature, stress and shrinkage were recorded and further treated with curves drawn by computer through A/D conversion. Results indicated that AZ91 alloy would precipitate eutectic phase not coinciding with equilibrium phase diagram under the conventional solidification condition. The temperature most susceptible to be hot torn was located near the practical solidified end temperature(420 ℃) for AZ91 alloy.更多还原