拉伸工艺参数对AZ31镁合金塑性的影响

Research on improving plasticity of AZ31 magnesium alloy by varying the tensile process

在温度为18℃~450℃、应变速率10-2s-1~10-4s-1范围内,对挤压态AZ31镁合金沿挤压方向进行拉伸试验。结果表明,当温度T≤100℃时,应变速率对试样伸长率影响较小,断口分析表明试样为脆性断裂;当温度为250℃~400℃,伸长率随应变速率的减小而迅速增加,变形激活能为170 k J/mol,交滑移控制的动态再结晶是导致塑性提高的主要原因;温度为400℃~450℃、应变速率10-4s-1拉伸时,伸长率下降,原因是高温、长时间拉伸会引起空洞扩张,降低了有效承载面积,导致塑性降低。

A tensile test along the extrusion direction of AZ31 magnesium alloy specimen was carried out with strain rate from 10-2 s -1 to 10-4s -1 at 18℃ - 450℃. The results show that when T≤ 100℃ elongation changes slightly with strain rate and brittleness rupture is sig- nificant in the SEM image. At 250℃ -400℃, elongation increases rapidly with decreasing of strain rate and the calculated active energy is about 170 kJ ~ tool-1 ,which indicates that the dynamic recrystallization controlled by cross dislocation glide is the main cause of plasticity improvement. However, the elongation decreases with strain rate of 10-4 s-l at 400℃ - 450℃. The reason is that long-time tension and high temperature will enlarge cavitation, re- duce efficient area to bear the load and finally decrease plasticity.