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Acta Metall Sin  2022, Vol. 58 Issue (9): 1118-1128    DOI: 10.11900/0412.1961.2021.00053
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Effect of Quenching Rate on Stress Corrosion Cracking Susceptibility of 7136 Aluminum Alloy
MA Zhimin1,2,3, DENG Yunlai1,3, LIU Jia2, LIU Shengdan1,3(), LIU Honglei4
1.School of Materials Science and Engineering, Central South University, Changsha 410083, China
2.Baotou Vocational and Technical College, Baotou 014030, China
3.Key Laboratory of Non-Ferrous Metal Materials Science and Engineering, Ministry of Education, Central South University, Changsha 410083, China
4.Northeast Light Alloy Company Ltd., Harbin 150060, China
Cite this article: 

MA Zhimin, DENG Yunlai, LIU Jia, LIU Shengdan, LIU Honglei. Effect of Quenching Rate on Stress Corrosion Cracking Susceptibility of 7136 Aluminum Alloy. Acta Metall Sin, 2022, 58(9): 1118-1128.

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Abstract  

7xxx series aluminum alloys are well-known structural materials, and they have been used in various fields, such as aerospace and vehicle, owing to their low density, high strength, and good formability. However, they are susceptible to stress corrosion cracking (SCC). SCC reduces the service life of these alloys and limits their application. With the development of the aerospace and vehicle industries, high-strength 7xxx series aluminum alloys are manufactured as semiproducts with large sections, such as thick plates, to avoid welding and jointing defaults. Quenching is a critical step for producing thick plates because their properties, such as SCC susceptibility, are sensitive to the quenching rate, and the quenching rate is generally lower at the center layer than at the surface layer during quenching. In this study, the effect of quenching rate on the SCC susceptibility of 7136 aluminum alloy was investigated using immersion end-quenching technique and slow strain rate tensile (SSRT) test. The strength, elongation, and fracture time of the samples after SSRT in oil and NaCl solution were obtained, and the crack features on and near the fracture surface were examined using SEM. SCC susceptibility was evaluated using the reduction rates of strength, elongation, fracture time, and stress corrosion sensitivity index (ISSRT). The mechanism is discussed herein based on microstructural examination using SEM, EBSD, STEM in a HAADF mode, and EDS. Results show that the SCC susceptibility of the alloy first increases and then decreases with the decrease in the quenching rate. The SCC susceptibility is the highest at the quenching rate of approximately 5.3°C/s with the Ithe number and size of quench-induced precipitates increase gradually, and the precipitate free zones (PFZs) near grain boundary (GB) and subgrain boundary (SGB) widen; and the contents of Zn and Mg in precipitates at grain boundaries increase rapidly when the quenching rate is greater than 5.3oC/s, and Cu content increases rapidly when the quenching rate is lower than 5.3oC/s. The quench-induced changes in the morphology and chemical composition of precipitates at GB/SGB are the main reasons for the SCC susceptibility to increase first and then decrease with the decrease in the quenching rate.

Key words:  aluminum alloy      stress corrosion cracking      quenching rate      microstructure     
Received:  29 January 2021     
ZTFLH:  TG146.2  
Fund: National Key Research and Development Program of China(2016YFB0300901);Scientific Research Project of Inner Mongolia Colleges and Universities(NJZY21092)
About author:  LIU Shengdan, professor, Tel: (0731)88830265, E-mail: lsd_csu@csu.edu.cn

URL: 

https://www.ams.org.cn/EN/10.11900/0412.1961.2021.00053     OR     https://www.ams.org.cn/EN/Y2022/V58/I9/1118

Fig.1  Schematic of end quenching and drawing of slow strain rate tensile sample (unit: mm; ED—extruded direction, ND—normal direction, TD—transverse direction; blue indicates the part in the water, gray indicates the part in the air)
Fig.2  Cooling curves and average quenching rates at different positions of the 7136 aluminum alloy sample
(a) time-temperature curve
(b) average quenching rate
Fig.3  Stress-strain curves of the 7136 aluminum alloy samples under quenching rates of 263.0, 5.3, and 1.8oC/s
Fig.4  The strength, elongation, and fracture time of 7136 aluminum alloy samples under different quenching rates, and corresponding reduction rate
(a) strength (RmOil is the strength in silicone oil, and RmNaCl is the strength in NaCl solution) and strength reduction rate (KR)
(b) elongation (AOil is the elongation in silicone oil, and ANaCl is the elongation in NaCl solution) and elongation reduction rate (KA)
(c) fracture time (tOil is the fracture time in silicone oil, and tNaCl is the fracture time in NaCl solution) and fracture time reduction rate (Kt)
Fig.5  Stress corrosion sensitivity index (ISSRT) of 7136 aluminum alloy samples under different quenching rates
Fig.6  Low (a-c) and locally high (a1-c1) magnified fracture SEM images of 7136 aluminum alloy samples in NaCl solution under quenching rates of 263.0oC/s (a, a1), 5.3oC/s (b, b1), and 1.8oC/s (c, c1)
Fig.7  SEM images near the fracture surface of 7136 aluminum alloy in NaCl solution under quenching rates of 263.0oC/s (a, a1, a2), 5.3oC/s (b, b1, b2), and 1.8oC/s (c, c1, c2)
(a-c) low magnification
(a1-c1) locally magnified images of box regions in Figs.7a-c, respectively
(a2-c2) locally magnified images of box regions in Figs.7a1-c1, respectively (GB—grain boundary, GBP—precipitate at grain boundary, SGB—sub-grain boundary)
Fig.8  Grain orientation maps of 7136 aluminum alloy samples under quenching rates of 263.0oC/s (a) and 1.8oC/s (b)
Fig.9  SEM images of 7136 aluminum alloy samples under quenching rates of 263.0oC/s (a) and 1.8oC/s (b)
Fig.10  STEM-HAADF images of 7136 aluminum alloy samples under quenching rates of 263.0oC/s (a), 5.3oC/s (b), and 1.8oC/s (c) (SGBP—precipitate at sub-grain boundary, PFZ—precipitate free zone)
Fig.11  Parameters of GBP, SGBP, and PFZ in 7136 aluminum alloy samples under different quenching rates
Fig.12  STEM-HAADF image (a) and EDS element maps of Al (b), Zn (c), Mg (d), and Cu (e) for 7136 aluminum alloy sample under quenching rate of 263.0oC/s
Fig.13  Contents of Zn, Mg, and Cu in GBPs of 7136 aluminum alloy samples under different quenching rates
Fig.14  Schematics of crack propagation of stress corrosion cracking (SCC) in 7136 aluminum alloy under quenching rates of 263.0oC/s (a), 5.3oC/s (b), and 1.8oC/s (c)
Fig.15  Proportions of grain boundaries and sub-grain boundaries with different PFZ widths in 7136 aluminum alloy samples under quenching rates of 5.3 and 1.8oC/s
1 Deng Y L, Zhang X M. Development of aluminium and aluminium alloy [J]. Chin. J. Nonferrous Met., 2019, 29: 2115
邓运来, 张新明. 铝及铝合金材料进展 [J]. 中国有色金属学报, 2019, 29: 2115
2 Rometsch P A, Zhang Y, Knight S. Heat treatment of 7xxx series aluminium alloys—Some recent developments [J]. Trans. Nonferrous Met. Soc. China, 2014, 24: 2003
doi: 10.1016/S1003-6326(14)63306-9
3 Knight S P, Pohl K, Holroyd N J H, et al. Some effects of alloy composition on stress corrosion cracking in Al-Zn-Mg-Cu alloys [J]. Corros. Sci., 2015, 98: 50
doi: 10.1016/j.corsci.2015.05.016
4 Chen S Y, Li J Y, Hu G Y, et al. Effect of Zn/Mg ratios on SCC, electrochemical corrosion properties and microstructure of Al-Zn-Mg alloy [J]. J. Alloys Compd., 2018, 757: 259
doi: 10.1016/j.jallcom.2018.05.063
5 Liu L, Jia Y Y, Jiang J T, et al. The effect of Cu and Sc on the localized corrosion resistance of Al-Zn-Mg-X alloys [J]. J. Alloys Compd., 2019, 799: 1
doi: 10.1016/j.jallcom.2019.05.189
6 Yu M Y, Zhang Y A, Li X W, et al. Effect of recrystallization on plasticity, fracture toughness and stress corrosion cracking of a high-alloying Al-Zn-Mg-Cu alloy [J]. Mater. Lett., 2020, 275: 128074
doi: 10.1016/j.matlet.2020.128074
7 Xie P, Chen S Y, Chen K H, et al. Enhancing the stress corrosion cracking resistance of a low-Cu containing Al-Zn-Mg-Cu aluminum alloy by step-quench and aging heat treatment [J]. Corros. Sci., 2019, 161: 108184
doi: 10.1016/j.corsci.2019.108184
8 Chen J F, Zhang X F, Zou L C, et al. Effect of precipitate state on the stress corrosion behavior of 7050 aluminum alloy [J]. Mater. Charact., 2016, 114: 1
doi: 10.1016/j.matchar.2016.01.022
9 Yuan D L, Chen K H, Chen S Y, et al. Enhancing stress corrosion cracking resistance of low Cu-containing Al-Zn-Mg-Cu alloys by slow quench rate [J]. Mater. Des., 2019, 164: 107558
doi: 10.1016/j.matdes.2018.107558
10 Jiang F Q, Huang J W, Jiang Y G, et al. Effects of quenching rate and over-aging on microstructures, mechanical properties and corrosion resistance of an Al-Zn-Mg (7046A) alloy [J]. J. Alloys Compd., 2021, 854: 157272
doi: 10.1016/j.jallcom.2020.157272
11 Chen S Y, Chen K H, Peng G S, et al. Effect of quenching rate on microstructure and stress corrosion cracking of 7085 aluminum alloy [J]. Trans. Nonferrous Met. Soc. China, 2012, 22: 47
doi: 10.1016/S1003-6326(11)61138-2
12 Xiao Q F, Xu Y M, Huang J W, et al. Effects of quenching agents, two-step aging and microalloying on tensile properties and stress corrosion cracking of Al-Zn-Mg-Cu alloys [J]. J. Mater. Res. Technol., 2020, 9: 10198
doi: 10.1016/j.jmrt.2020.07.014
13 Liu S D, Chen B, Li C B, et al. Mechanism of low exfoliation corrosion resistance due to slow quenching in high strength aluminium alloy [J]. Corros. Sci., 2015, 91: 203
doi: 10.1016/j.corsci.2014.11.024
14 Liu S D, Zhong Q M, Zhang Y, et al. Investigation of quench sensitivity of high strength Al-Zn-Mg-Cu alloys by time-temperature-properties diagrams [J]. Mater. Des., 2010, 31: 3116
doi: 10.1016/j.matdes.2009.12.038
15 Ma Z M, Liu J, Yang Z S, et al. Effect of cooling rate and grain structure on the exfoliation corrosion susceptibility of AA 7136 alloy [J]. Mater. Charact., 2020, 168: 110533
doi: 10.1016/j.matchar.2020.110533
16 Sun Y W, Pan Q L, Sun Y Q, et al. Localized corrosion behavior associated with Al7Cu2Fe intermetallic in Al-Zn-Mg-Cu-Zr alloy [J]. J. Alloys Compd., 2019, 783: 329
doi: 10.1016/j.jallcom.2018.12.151
17 Fang H C, Chao H, Chen K H. Effect of recrystallization on intergranular fracture and corrosion of Al-Zn-Mg-Cu-Zr alloy [J]. J. Alloys Compd., 2015, 622: 166
doi: 10.1016/j.jallcom.2014.10.044
18 Liao Y G, Han X Q, Zeng M X, et al. Influence of Cu on microstructure and tensile properties of 7xxx series aluminum alloy [J]. Mater. Des., 2015, 66: 581
doi: 10.1016/j.matdes.2014.05.003
19 Chemin A, Marques D, Bisanha L, et al. Influence of Al7Cu2Fe intermetallic particles on the localized corrosion of high strength aluminum alloys [J]. Mater. Des., 2014, 53: 118
doi: 10.1016/j.matdes.2013.07.003
20 Godard D, Archambault P, Aeby-Gautier E, et al. Precipitation sequences during quenching of the AA 7010 alloy [J]. Acta Mater., 2002, 50: 2319
doi: 10.1016/S1359-6454(02)00063-0
21 Chen J S, Li X W, Xiong B Q, et al. Quench sensitivity of novel Al-Zn-Mg-Cu alloys containing different Cu contents [J]. Rare Met., 2020, 39: 1395
doi: 10.1007/s12598-017-0981-y
22 Du Y, Chang Y A, Huang B Y, et al. Diffusion coefficients of some solutes in fcc and liquid Al: Critical evaluation and correlation [J]. Mater. Sci. Eng., 2003, A363: 140
23 Garner A, Euesden R, Yao Y C, et al. Multiscale analysis of grain boundary microstructure in high strength 7xxx Al alloys [J]. Acta Mater., 2021, 202: 190
doi: 10.1016/j.actamat.2020.10.021
24 Song R G, Dietzel W, Zhang B J, et al. Stress corrosion cracking and hydrogen embrittlement of an Al-Zn-Mg-Cu alloy [J]. Acta Mater., 2004, 52: 4727
doi: 10.1016/j.actamat.2004.06.023
25 Tanguy D, Bayle B, Dif R, et al. Hydrogen effects during IGSCC of pure Al-5Mg alloy in NaCl media [J]. Corros. Sci., 2002, 44: 1163
doi: 10.1016/S0010-938X(01)00140-8
26 Magnin T, Chambreuil A, Bayle B. The corrosion-enhanced plasticity model for stress corrosion cracking in ductile fcc alloys [J]. Acta Mater., 1996, 44: 1457
doi: 10.1016/1359-6454(95)00301-0
27 Song F X, Zhang X M, Liu S D, et al. The effect of quench rate and overageing temper on the corrosion behaviour of AA7050 [J]. Corros. Sci., 2014, 78: 276
doi: 10.1016/j.corsci.2013.10.010
28 Christodoulou L, Flower H M. Hydrogen embrittlement and trapping in Al-6%-Zn-3%-Mg [J]. Acta Metall., 1980, 28: 481
doi: 10.1016/0001-6160(80)90138-8
29 Tsai T C, Chuang T H. Role of grain size on the stress corrosion cracking of 7475 aluminum alloys [J]. Mater. Sci. Eng., 1997, A225: 135
30 Wang L, Dong C F, Zhang D W, et al. Effect of alloying elements on initial corrosion behavior of aluminum alloy in Bangkok, Thailand [J]. Acta Metall. Sin., 2020, 56: 119
王 力, 董超芳, 张达威 等. 合金元素对铝合金在泰国曼谷地区初期腐蚀行为的影响 [J]. 金属学报, 2020, 56: 119
31 Sarkar B, Marek M, Starke E A. The effect of copper content and heat treatment on the stress corrosion characteristics of Al-6Zn-2Mg-XCu alloys [J]. Metall. Trans., 1981, 12A: 1939
32 Rao A C U, Vasu V, Govindaraju M, et al. Stress corrosion cracking behaviour of 7xxx aluminum alloys: A literature review [J]. Trans. Nonferrous Met. Soc. China, 2016, 26: 1447
doi: 10.1016/S1003-6326(16)64220-6
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