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中南大学学报(自然科学版)

Journal of Central South University

第48卷    第3期    总第271期    2017年3月

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文章编号:1672-7207(2017)03-0578-07
预时效对7020铝合金组织与性能的影响
杨涛1, 2,叶凌英1, 2,刘胜胆1, 2,单朝军1, 2,王国玮1, 2,陈敏1, 2,邓运来1, 2,张新明1, 2

(1. 中南大学 材料科学与工程学院,湖南 长沙,410083;
2. 中南大学 轻合金研究院,湖南 长沙,410083
)

摘 要: 采用维氏硬度(HV)、电导率测试(EC)、扫描电镜(SEM)、透射电镜(TEM)、室温拉伸、冲击韧性实验研究预时效对7020铝合金组织与性能的影响。研究结果表明:合金经470 ℃固溶1 h后进行65 ℃预时效处理,与直接双级时效对比,合金的拉伸性能随预时效时间的延长而逐渐上升;65 ℃/168 h+90 ℃/8 h+160 ℃/26 h的抗拉强度为355.9 MPa,屈服强度为290.5 MPa,伸长率为16.3%,维氏硬度为120.9,电导率为22.4 MS/m;直接双级时效时,抗拉强度为320.4 MPa,屈服强度为256.7 MPa,伸长率为17.6%;维氏硬度为103.5,电导率为21.9 MS/m;合金经470 ℃固溶1 h后进行65 ℃预时效处理时,沿挤压方向和垂直挤压方向冲击吸收功分别为52.1 J和45.9 J;直接双级时效时,沿挤压方向和垂直挤压方向冲击吸收功分别为43.5 J和38.8 J;时效析出相随预时效时间的延长在晶内、晶界越来越细小弥散,晶界析出相断续分布。

 

关键字: 7020铝合金;预时效;拉伸性能;冲击韧性;显微组织

Effects of pre-aging on microstructures and mechanical properties of 7020 aluminum alloy
YANG Tao1, 2, YE Lingying1, 2, LIU Shengdan1, 2, SHAN Chaojun1, 2, WANG Guowei1, 2, CHEN Min1, 2, DENG Yunlai1, 2, ZHANG Xinming1, 2

1. School of Material Science and Engineering, Central South University, Changsha 410083, China;2. Light Alloy Research Institute, Central South University, Changsha 410083, China

Abstract:The effects of pre-ageing treatment on the mechanical properties of 7020 aluminum alloy were investigated by means of Vickers hardness (HV), electrical conductivity measurement (EC), scanning electron microscopy (SEM), transmission electron microscopy (TEM), tensile test and impact toughness tests. The results show that after 470 ℃/1 h solution treatment followed by pre-aging at 65 ℃, the mechanical properties of investigated alloy’s increase with the increase of the pre-aging time, while impact energy increases at first and then decreases. Compared to the direct two-stage aging at 65 ℃/168 h+90 ℃/8 h+160 ℃/26 h, the tensile strength, yield strength and elongation are 355.9 MPa, 290.5 MPa and 16.3%, respectively; the Vickers hardness is 120.9, and conductivity is 22.4 MS/m. However, for direct two-stage aging, the tensile strength, yield strength and elongation are 320.4 MPa, 256.7 MPa and 17.6%, respectively; Vickers hardness is 104.7, and conductivity is 21.9 MS/m. For 470 ℃/1 h solution treatment followed by pre-aging at 65 ℃, impact energy along the direction of extrusion and perpendicular to that are 52.1 J and 45.9 J, respectively, and for the direct two-stage aging, impact energy along the direction of extrusion and perpendicular to that are 43.5 J and 38.8 J, respectively. The distribution of precipitates inside the grains and at the grain boundaries are more finely dispersed within the extension of pre-aging time. Precipitates at the grain boundaries are discontinuous.

 

Key words: 7020 aluminum alloy; pre-aging; tensile properties; impact toughness; microstructure

中南大学学报(自然科学版)
  ISSN 1672-7207
CN 43-1426/N
ZDXZAC
中南大学学报(英文版)
  ISSN 2095-2899
CN 43-1516/TB
JCSTFT
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