AZ61镁合金的热变形行为及加工图
AZ61镁合金的真应力峰值和峰值应力所对应的应变会随应变速率的降低、变形温度的升高而减小。本文采用双曲正弦函数 关系来描述AZ61镁合金在塑性变形行为过程中的真应力、应变速率和变形温度之间的关系。该合金在塑性变形行为过程中的变形激活能为Q=112.969kJ/mol，应力因子 =0.0105MPa-1，应力指数n=7.23。
变形温度和应变速率可控制AZ61镁合金在塑性变形过程中的动态再结晶。在塑性变形过程中，材料在低温下存在大量孪晶，随着变形温度的升高和应变速率的降低，孪晶数量逐渐减少，并开始动态再结晶，使晶粒细化。
通过AZ61镁合金的塑性变形行为得到的实验数据来建立该材料在热塑性变形行为过程中的热加工图。由热加工图表明，该材料在低温低速和高温中速的变形条件下出现失稳情况。最终得到的最佳热变形条件为变形温度为340-400℃，应变速率为0.01s-1。此时功能转化率为最大值，变形后的材料的性能最好。
毕业论文关键词：AZ61镁合金；真应力；塑性变形行为；热激活能；热加工图；功能转化效率
The thermal deformation behavior and the thermal processing map of AZ61 magnesium alloy
Abstract
The plastic deformation behavior of AZ61 magnesium alloy during different temperatures (250-400℃) and strain rates (0.01-10s-1) are studied on Gleeble-1500 .The results show that the true stress of the material will be varies with deformation conditions changing.
With the lower strain rate and higher deformation temperature , true stress peak and corresponding strain of AZ61 magnesium alloy will significantly reduce. In this paper, the Arrhenius function, ,describe the relationship between the true stress of AZ61 magnesium alloy of different strain rate and temperature during the process of plastic deformation behavior . During the process of plastic deformation behavior,tensile deformation activation energy of this alloy is 112.969kJ/mol ,stress factor α = 0.0105MPa-1, stress exponent n =7.23
The deformation temperature and the strain rate control the nucleation mechanism of DRX during the plastic deformation of AZ61 magnesium alloy. A large number of twins are observed at lower temperature. With temperature rise and strain rate reduce, twins gradually reduce and dynamic re-crystallization finer grain size.
Using the experimental data in plastic deformation behavior of AZ61 magnesium alloy obtained to establish the thermal processing graph during the thermoplastic deformation behavior .The thermal processing graph shows that AZ61 magnesium alloy will be instability under the condition of lower speed at lower temperature and medium speed at higher temperature. Best of hot deformation conditions for the deformation temperature at 340-400℃, strain rate of 0.01s-1.Then, AZ61 magnesium alloy get the maximum conversion rate of the functional and material performance after deformation is best.
Key words：AZ61 magnesium alloy ； thermal processing map；true stress ； plastic deformation behavior ； thermal activation energy ； functional conversion efficiency
目录
第一章 绪论 1
1.1 镁及其合金的概述 1
1.1.1 镁的性质 1
1.1.2镁合金的应用及发展前景 2
1.1.3Mg-Al-Zn系镁合金的概述 2
1.2镁合金的塑性变形 3
1.2.1镁合金塑性变形机制 3
1.2.2镁合金塑性成形工艺 4
1.2.3镁合金的塑性成形的特点 5
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