7136铝合金的热变形与动态再结晶行为

Thermal deformation and dynamic recrystallization behavior of 7136 aluminum alloy

明确7136铝合金的热变形和动态再结晶行为对于制定合理的加工工艺参数具有重要意义。试验亦分析了7136铝合金试样在变形温度为350℃~470℃、应变速率为0.01s^-1~10s^-1条件下的热变形与动态再结晶行为,建立了合金的流变应力模型,并通过挤压试验和数值模拟验证了流变应力本构方程的合理性。结果表明,7136铝合金在350℃条件下进行热加工发生动态再结晶,再结晶百分数随温度升高而增加,随应变速率增加而减少:应变速率为0.01s^-1、变形温度由375℃上升到450℃时,再结晶百分数由6.8%逐渐增加至8.2%;变形温度为400℃、应变速率由0.01s^-1提高至10s^-1时,再结晶百分数由7.6%逐渐减少至4.9%。所获得的本构方程用于挤压过程的数值模拟,稳态阶段模拟与实际载荷位移曲线误差不超过5%。7136铝合金热挤压过程应选择较低的挤压温度和较高的挤压速度,以降低其动态再结晶百分数。

To define thermal deformation and dynamic recrystallization behavior of 7136 aluminum alloy is of great significance for setting reasonable processing parameters. Thermal deformation and dynamic recrystallization behavior of 7136 aluminum alloy specimens are analyzed,the flow stress model is established,and the rationality of the constitutive equation is verified by extrusion experiment and numerical simulation,when deformation temperature and strain rate are set at 350-470℃ and 0.01-10s^-1 respectively in the experiment. The results show that dynamic recrystallization of 7136 aluminum alloy begins at 350℃,and the percentage of recrystallization increases with the increase of temperature and decreases with the increase of strain rate. The percentage of recrystallization gradually increases from 6. 8% to 8. 2% when the strain rate is 0. 01s^-1 and deformation temperature is increased from 375℃ to 450℃. When deformation temperature is 400℃ and strain rate is increased from 0. 01s^-1 to 10s^-1 ,recrystallization percentage decreases gradually from 7.6% to 4.9%.The constitutive equation obtained in this paper is used to simulate the extrusion process. The error between the steady-state simulation and the actual load-displacement curve is less than 5%.Lower extrusion temperature and higher extrusion speed should be chosen for 7136 aluminum alloy hot extrusion to reduce the percentage of dynamic recrystallization.