锻压技术

7075铝合金热成形析出相演化规律和强度预测模型

英文标题：Evolution laws of precipitated phases and strength prediction model for 7075 aluminum alloy during hot forming

单位：1. 武汉理工大学现代汽车零部件技术湖北省重点实验室 2. 武汉理工大学汽车零部件技术湖北省协同创新中心 3.武汉理工大学材料绿色精密成形技术与装备湖北省工程中心 4.武汉工程大学机电工程学院

分类号：TG146.21

出版年,卷(期):页码：2021,46(9):105-111

摘要：

热成形后产生的位错会导致时效过程中基体和位错上析出相的形核与长大存在竞争，根据7075铝合金热拉伸实验得到的流变应力Arrhenius方程来描述热变形过程中析出相在位错上的析出行为和位错硬化行为。基于晶体学和析出动力学，通过热拉伸实验和TEM分析铝合金热冲压成形后析出相的体积分数、析出相单位原子体积和动力学的关联关系，利用热力学分析析出相的尺寸演化，并将材料的流变行为和屈服强度贡献相结合，建立了HFQ工艺析出相的析出演化模型和屈服强度预测模型。结果显示：强化析出相η′的体积分数随着时效时间的延长（0~28 h），先快速上升，达到峰值后出现一段平稳期，然后迅速下降，强化析出相η′的尺寸随着时效时间的延长（0~28 h）而增大，随着变形量的增大（10%~25%）而增大。

The dislocations generated after hot forming caused the nucleation and growth of precipitated phases on the matrix and dislocation to compete during the aging process, and according to the rheological stress Arrhenius equation obtained by thermal tensile experiment of 7075 aluminum alloy, the precipitation behavior and hardening behavior of dislocation for the precipitated phase during the thermal deformation process were described. Therefore, based on crystallography and precipitation dynamics, the correlation relationship among volume fraction of the precipitated phases, unit atomic volume of the precipitated phases and kinetics after the thermal stamping of aluminum alloy were analyzed by thermal tensile experiment and TEM, the size evolution of the precipitated phase was analyzed by thermodynamics, and the precipitation evolution model and yield strength prediction model for precipitated phases of HFQ process were established by combining the rheological behavior of material with the yield strength. The results show that the volume fraction of enhanced precipitated phase η′ increases rapidly with the extension of aging time of 0-28 h and reaches the peak, and then presents a stable period, next decreases rapidly. In addition, the size of enhanced precipitated phase η′ also increases with the increasing of aging time of 0-28 h and deformation amount of 10%-25%.

基金项目：

国家重点研发计划(2019YFB1704500)；国家自然科学基金资助项目(51775397)；湖北省重点研发计划项目(2020BAB140)；湖北省技术创新重大专项(2019AAA007)；武汉市科技成果转化专项(2019030703011511)

胡志力（1983-），男，博士，教授 E-mail：zhilihuhit@163.com

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