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利用Gleeble-1500在250~500℃和应变速率0.001~1 s-1对铸态AZ31镁合金进行热压缩及热拉伸试验,对热变形过程中拉-压不对称性进行研究;基于Hollomon公式,分析了铸态AZ31镁合金热拉伸-压缩过程中应变硬化指数的变化规律。结果表明:铸态镁合金在热拉伸-压缩过程中,存在明显拉-压不对称性,热拉伸应变硬化指数均比热压缩应变硬化指数大;升高形变温度及降低应变速率有利于减小铸态镁合金的拉-压不对称性。
The as-cast AZ31 magnesium alloy was subjected to hot-compression and hot-stretching tests at 250-500 ℃ and strain rate of 0.001-1s-1 using Gleeble-1500 to study the tension-pressure asymmetry in the hot deformation process. Based on Hollomon’s formula , The change law of strain hardening index during hot drawing-compression of as-cast AZ31 magnesium alloy was analyzed. The results show that there is a significant tensile-pressure asymmetry in the as-cast magnesium alloy during hot drawing-compression process, and the hot-drawn strain hardening index is higher than that of the hot-compressive strain hardening index. Increasing the deformation temperature and decreasing the strain rate are favorable Reducing the tension-pressure asymmetry of as-cast magnesium alloy.