金属热处理 ›› 2022, Vol. 47 ›› Issue (3): 44-47.DOI: 10.13251/j.issn.0254-6051.2022.03.008

• 工艺研究 • 上一篇    下一篇

RRA过程中预时效时间对7A85铝合金组织性能的影响

杨春苗1, 王珊1, 王淑慧1,2, 李延珍3, 刘文文1,2   

  1. 1.烟台南山学院 工学院, 山东 烟台 265713;
    2.烟台南山学院 轻合金加工成形实验室, 山东 烟台 265700;
    3.航鑫材料科技有限公司, 山东 烟台 265700
  • 收稿日期:2021-10-24 修回日期:2021-01-04 出版日期:2022-03-25 发布日期:2022-04-22
  • 通讯作者: 刘文文,讲师,硕士,E-mail:liuwenwen@nanshan.edu.cn
  • 作者简介:杨春苗(1982—),女,讲师,硕士,主要研究方向为金属材料的性能优化,E-mail: yangchunmiao@nanshan.edu.cn。
  • 基金资助:
    山东省高等学校青创科技计划(2019KJA019)

Influence of pre-aging time on microstructure and properties of 7A85 aluminum alloy during RRA process

Yang Chunmiao1, Wang Shan1, Wang Shuhui1,2, Li Yanzhen3, Liu Wenwen1,2   

  1. 1. College of Engineering, Yantai Nanshan University, Yantai Shandong 265713, China;
    2. Light Alloy Processing Laboratory, Yantai Nanshan University, Yantai Shandong 265700, China;
    3. Hangxin Material Testing Technology Co., Ltd., Yantai Shandong 265700, China
  • Received:2021-10-24 Revised:2021-01-04 Online:2022-03-25 Published:2022-04-22

摘要: 系统研究了RRA处理过程预时效时间对7A85铝合金微观组织演变和性能的影响。利用Jmat-Pro软件计算了相变规律和TTT图,测试了硬度和拉伸性能指标,利用TEM表征了微观组织。结果表明,热力学平衡状态下,410 ℃开始析出MgZn2相,体积分数达到9.5%左右;等温过程最先析出GP区,析出温度为室温~175 ℃,鼻尖温度在150 ℃左右;随着预时效时间的延长,硬度先升高后降低,20 h时达到峰值硬度192 HV;RRA处理过程,预时效时间为12 h时,屈服强度和抗拉强度达到峰值,分别为625 MPa和675 MPa;120 ℃保温20 h峰值时效状态下,η′-MgZn析出相尺寸在5~10 nm;预时效时间为12 h时,RRA处理后晶界处的Al-Zn-Mg-Cu四元相粒子呈不连续分布,尺寸在50~125 nm范围。

关键词: 7A85铝合金, 预时效处理, RRA处理, 微观组织, 硬度

Abstract: Influence of pre-aging time on microstructure and properties of the 7A85 aluminum alloy during RRA process was investigated. The thermodynamic equilibrium phase transformation and TTT curves were calculated by Jmat-Pro. The hardness and tensile properties were tested and microstructure was characterized by means of TEM. The results indicate that MgZn2 phase begins to precipitate at 410 ℃ under thermodynamic equilibrium, volume fraction of which reaches about 9.5%. The GP zone is precipitated first during the isothermal process in the temperature range of room temperature to 175 ℃, and the nose tip temperature is about 150 ℃. With the extension of pre-aging time, the hardness first increases and then decreases, and reaches a peak hardness of 192 HV after aging for 20 h. The yield strength and tensile strength reach the peak value of 625 MPa and 675 MPa, respectively, when the pre-aging time is 20 h during the RRA process. During the heat preservation process at 120 ℃, under the peak aging state of 20 h, the size of the η′-MgZn precipitated phase is 5-10 nm. When the pre-aging time is 12 h, the Al-Zn-Mg-Cu quaternary phase particles with the size of 50-125 nm at the grain boundaries are discontinuously distributed after RRA treatment.

Key words: 7A85 aluminum alloy, pre-aging treatment, RRA treatment, microstructure, hardness

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