Cracking Cause of 7075 Aluminum Alloy High Lock Nut
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摘要: T6态7075铝合金经由热处理转变为T73态后制造的高锁螺母，在大气环境下服役约3.5 a后多件发生开裂，通过化学成分分析、组织和断口形貌观察、残余应力测试等方法分析了开裂原因。结果表明：7075铝合金高锁螺母在服役过程发生了应力腐蚀开裂。高锁螺母安装后，其收口部位产生周向残余拉应力，表面氧化膜层开裂使得金属基体与大气中腐蚀性介质接触；7075铝合金在由T6态转变为T73态的热处理过程中，第二相沿晶界局部连续析出，为裂纹萌生和扩展提供了通道。在这些因素的共同作用下，高锁螺母发生应力腐蚀开裂。Abstract: High lock nuts were made from 7075-T73 aluminum alloy that was obtained by T73 heat-treating 7075-T6 aluminum alloy. After serving in an atmospheric environment for about 3.5 a, many nuts cracked. The crack reason was analyzed by chemical composition analysis, microstructure and fracture morphology observation, residual stress testing and other methods. The results show that stress corrosion cracking occurred in the 7075 aluminum alloy high lock nut during service. After the high lock nut was installed, the circumferential residual tensile stress was generated at the closing part, and the surface oxide film was cracked, making the metal substrate in contact with corrosive media in atmosphere. The second phase precipitated locally and continuously along grain boundaries during the heat treatment from T6 to T73 states, providing channels for crack initiation and propagation. Under the combination of these factors, stress corrosion cracking occurred in the high lock nut.
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Keywords:
- 7075 aluminum alloy /
- high lock nut /
- failure analysis /
- stress corrosion /
- heat treatment
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[1] 丁清伟, 张迪, 刘浩然, 等.Al-xMg-3.1Zn铝合金的应力腐蚀开裂行为及其机制[J].稀有金属材料与工程, 2020, 49(5):1601-1606. DING Q W, ZHANG D, LIU H R, et al.Stress corrosion cracking behavior of Al-xMg-3.1Zn aluminum alloys and its mechanism[J].Rare Metal Materials and Engineering, 2020, 49(5):1601-1606.
[2] 王祝堂, 田荣璋.铝合金及其加工手册[M].2版.长沙:中南大学出版社, 2000. WANG Z T, TIAN R Z.Aluminum alloy and its processing manual[M].2nd ed.Changsha:Central South University Press, 2000.
[3] 何春霞, 秦国帅, 吴素珍, 等.热处理工艺对7075铝合金性能的影响[J].热加工工艺, 2016, 45(12):203-206. HE C X, QIN G S, WU S Z, et al.Effect of heat treatment on properties of 7075 aluminium alloy[J].Hot Working Technology, 2016, 45(12):203-206.
[4] 王江涛, 谭文胜, 周东帅, 等.固溶时效对7075铝合金微观组织和力学性能的影响[J].金属热处理, 2017, 42(12):148-154. WANG J T, TAN W S, ZHOU D S, et al.Effects of solution treatment and aging on microstructure and mechanical properties of 7075 aluminum[J].Heat Treatment of Metals, 2017, 42(12):148-154.
[5] 丰亮东, 易丹青, 刘会群, 等.温度对Al-Zn-Mg-Cu合金应力腐蚀敏感性的影响[J].热加工工艺, 2019, 48(4):79-81. FENG L D, YI D Q, LIU H Q, et al.Influence of temperature on stress corrosion susceptibility of Al-Zn-Mg-Cu alloy[J].Hot Working Technology, 2019, 48(4):79-81.
[6] 刘继华, 李荻, 刘培英.热处理对7075铝合金应力腐蚀及断口形貌的影响[J].材料热处理学报, 2010, 31(7):109-113. LIU J H, LI D, LIU P Y.Effect of heat treatment on stress corrosion behavior of 7075 aluminum alloy[J].Transactions of Materials and Heat Treatment, 2010, 31(7):109-113.
[7] SHE H, CHU W, DA SHU, et al.Effects of silicon content on microstructure and stress corrosion cracking resistance of 7050 aluminum alloy[J].Transactions of Nonferrous Metals Society of China, 2014, 24(7):2307-2313.
[8] 刘继华, 李荻, 朱国伟, 等.7075铝合金应力腐蚀敏感性的SSRT和电化学测试研究[J].腐蚀与防护, 2005, 26(1):6-9. LIU J H, LI D, ZHU G W, et al.Stress corrosion susceptibility of 7075 aluminum alloy studied by SSRT and electrochemical tests[J].Corrosion & Protection, 2005, 26(1):6-9.
[9] 陈小明, 宋仁国.7000系铝合金应力腐蚀开裂的研究进展[J].腐蚀科学与防护技术, 2010, 22(2):120-123. CHEN X M, SONG R G.Progress in research on stress corrosion cracking of 7000 series aluminum alloys[J].Corrosion Science and Protection Technology, 2010, 22(2):120-123.
[10] 黄磊萍.不同热处理工艺对7N01和7075铝合金腐蚀行为的影响[D].长沙:湖南大学, 2017. HUANG L P.Influence of heat treatment on corrosion behavior of 7N01 and 7075 aluminum alloy[D].Changsha:Hunan University, 2018.
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