粗晶粒铸轧AZ31镁合金的高温拉伸性能

研究了具有较大晶粒尺寸铸轧态AZ31镁合金的高温拉伸性能。通过热处理获得晶粒尺寸d=27．8μm的板材，对不同试样，在温度分别为300，350，400，450℃恒温条件下，以10^-3s^-1和10^-3s^-1恒定拉伸速率对试样进行拉伸至失效实验。结果表明，粗晶粒AZ31镁合金在450℃和10^-3s^-1条件下达到最大的延伸率106．7％。拉伸试样断口形貌的分析表明，450℃时出现丝状物质是合金出现液态zn的结果。少量的液相可以释放应力集中和协调此时的变形过程。与细晶粒铸轧态AZ31相比，在拉伸条件相同和晶粒尺寸不同的情况下，粗晶粒的塑形较低，其原因是晶界滑移在变形时所作贡献少。

High temperature tensile performance of twin-roll casted and coarse-grained AZ31 magnesium alloy

High temperature tensile performance of a twin-roll casted AZ31 magnesium alloy with large grain size is investigated. The grain size （ d = 27.8 μm） is coarsen through heat treatment. Under constant temperatures （300,350,400 and 450℃ ）, elongation-to-failure tests are conducted under constant tensile rates of 10^-3s^-1 and 10 ^-2s^-1. The investigation suggests that the maximum elongation of 106. 7% is obtained at 450 ℃ and 10^-3s^-1. Fracture morphology of the tensile specimens shows that the thread of liquid Zn appears at 450℃. The existence of a few liquid phase could release the stress concentration and coordinate deformation process. By comparing with the fine-grained AZ31, the investigated AZ31 alloy with larger grains offers a lower tensile ductility under the same tensile condition, which may be ascribed to the less contribution of grain boundary sliding to ductility.