金属热处理 ›› 2020, Vol. 45 ›› Issue (7): 63-67.DOI: 10.13251/j.issn.0254-6051.2020.07.013

• 工艺研究 • 上一篇    下一篇

Al-6.8Zn-2.3Mg-2.0Cu-0.15Sc合金的高温回归再时效工艺

史文杰, 王春华   

  1. 烟台南山学院 工学院, 山东 烟台 265713
  • 收稿日期:2020-01-05 出版日期:2020-07-25 发布日期:2020-09-07
  • 通讯作者: 王春华, 副教授, 硕士, E-mail:412404460@qq.com
  • 作者简介:史文杰(1977—), 男, 讲师, 硕士, 主要研究方向为金属材料研究与机械CAD设计, E-mail:swenj549@sina.com。
  • 基金资助:
    山东省重点研发计划(2017GGX20130);山东省高等学校科技计划(J18KB046)

High-temperature retrogression and re-aging process of Al-6.8Zn-2.3Mg-2.0Cu-0.15Sc alloy

Shi Wenjie, Wang Chunhua   

  1. College of Engineering, Yantai Nanshan University, Yantai Shandong 265713, China
  • Received:2020-01-05 Online:2020-07-25 Published:2020-09-07

摘要: 采用硬度计、数字涡流金属电导仪、透射电镜(TEM)、万能拉伸试验机、扫描电镜(SEM)等对Al-6.8Zn-2.3Mg-2.0Cu-0.15Sc合金在高温回归再时效(RRA)过程中的性能与组织演变规律进行研究。结果表明:合金在170 ℃回归时,具有较高硬度与优良的抗电化学腐蚀性能,合金170 ℃回归1 h时主相η′细小弥散数量众多,在形变过程中借助位错切过与Orowan机制强化合金,强度可达625.1 MPa,伸长率达9.6%,获得了优于单级时效(T6)G.P.区强化达到的强度592.4 MPa、伸长率6.5%,强度提高32.7 MPa,伸长率提高47.7%,拉伸断口形貌SEM显示为完全的韧性断裂特征。Al-6.8Zn-2.3Mg-2.0Cu-0.15Sc合金的优秀RRA工艺为140 ℃×24 h+170 ℃×1 h+160 ℃×24 h。

关键词: 高温回归再时效, 导电率, 强化机制

Abstract: Properties and microstructure evolution laws of Al-6.8Zn-2.3Mg-2.0Cu-0.15Sc alloy in the process of high-temperature retrogression and re-aging (RRA) were studied via technological means such as sclerometer, digital eddy current metal conductometer, transmission electron microscope (TEM), universal tensile testing machine and scanning electron microscope (SEM). The results show that in the retrogressive process at 170 ℃ the alloy has high hardness and excellent electrochemical corrosion resistance. The principal phase η′ of the alloy is fine, dispersed and numerous after the retrogressive process at 170 ℃ for 1 h, and it strengthens the alloy with Orowan mechanism by virtue of dislocation cutting in the process of deformation. Therefore, it achieves the strength of 625.1 MPa and the elongation of 9.6 %, and is superior to one-step aging (T6) G.P. area with the strength of 592.4 MPa and the elongation of 6.5%. The strength is enhanced by 32.7 MPa and the elongation is increased by 47.7%. In addition, the appearance of tensile fracture presentes a complete ductile fracture characteristic via SEM. The excellent RRA process of the Al-6.8Zn-2.3Mg-2.0Cu-0.15 Sc alloy is aging at 140 ℃ for 24 h, regression aging at 170 ℃ for 1 h and re-aging at 160 ℃ for 24 h.

Key words: high-temperature retrogression and re-aging, electrical conductivity, strengthening mechanism

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