The Non-Isothermal Double Ageing Behaviour of 7055 Aluminum Alloy

doi:10.11900/0412.1961.2020.00039

Acta Metall Sin

2020, Vol. 56

Issue (11): 1495-1506 DOI: 10.11900/0412.1961.2020.00039

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The Non-Isothermal Double Ageing Behaviour of 7055 Aluminum Alloy

LI Jichen¹, FENG Di¹^,²(

), XIA Weisheng², GUO Weimin³(

), WANG Guoying¹

1 School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, China
2 School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
3 State Key Laboratory for Marine Corrosion and Protection, Luoyang Ship Material Research Institute, Qingdao 266237, China

Cite this article:

LI Jichen, FENG Di, XIA Weisheng, GUO Weimin, WANG Guoying. The Non-Isothermal Double Ageing Behaviour of 7055 Aluminum Alloy. Acta Metall Sin, 2020, 56(11): 1495-1506.

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Abstract

Thick plates of 7055 aluminum alloy are widely used as structural components, especially in the aerospace industry, due to their high strength, low density, excellent hot workability, and high stress-corrosion resistance, which are dependent on the type of thermal treatment the alloy is subjected to. Because of the heating and cooling stages in such components, non-isothermal ageing has attracted a lot of research interests. Replacing isothermal ageing with non-isothermal ageing is needed for higher efficiency and practicability. Herein, a novel isothermal-ageing technique based on double ageing is developed. Hardness test, electrical conductivity test, room-temperature tensile test, exfoliation corrosion test, DSC, and TEM analyses were employed to study the influence of non-isothermal double ageing on microstructure and properties of the 7055 aluminum alloy. The results showed that in the heating stage of the second ageing treatment, inner grains of the microstructure evolved from a three-phase coexistence state containing the GP zone, η′ phase, and α-Al to that containing η′ phase, η phase, and α-Al. On the other hand, in the continuous cooling stage of the second ageing, GP zone and η′ phase re-precipitated, resulting in improved hardness. The η phase on the grain boundary became coarse and discontinuously distributed, which resulted in a progressive improvement of the electrical conductivity. The heating rate and highest ageing temperature (T_p) of the second ageing stage determined the final properties. With a standard electrical conductivity of 22 MS/m, 1 ℃/min heating rate corresponds to the T_p of 215 ℃, while T_p of 225 ℃ is needed when heating by 3 ℃/min. After pre-aged by 105 ℃, 24 h and non-isothermal ageing including heating and cooling stages, the strength and exfoliation corrosion resistance of approximately 610 MPa and EB level were achieved, respectively. The alloy showed a better comprehensive performance than the T6 and T73 state ones. Additionally, the non-isothermal ageing removing the heat preservation stage realized the short process preparation.

Key words: 7055 aluminum alloy non-isothermal ageing strength exfoliation corrosion

Received: 10 February 2020

ZTFLH:

TG146.2

Fund: National Natural Science Foundation of China(51801082);Open Research Fund of State Key Laboratory for Marine Corrosion and Protection(KF190409)

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	Jichen LI
	Di FENG
	Weisheng XIA
	Weimin GUO
	Guoying WANG

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https://www.ams.org.cn/EN/10.11900/0412.1961.2020.00039 OR https://www.ams.org.cn/EN/Y2020/V56/I11/1495

Fig.1 Schematic of the non-isothermal ageing process of 7055 aluminum alloy (T_p—the highest ageing temperature)

Fig.2 The electrical conductivity evolution curves of 7055 aluminum alloy during heating ageing stage under heating rates 1 ℃/min (a) and 3 ℃/min (b), respectively (The electrical conductivity evolution curves during the cooling stages followed heating ageing are also showed in Figs.2a and b (partial temperature points), respectively)

Fig.3 The hardness evolution curves of 7055 aluminum alloy during heating ageing stage under heating rates 1 ℃/min (a) and 3 ℃/min (b), respectively (The hardness evolution curves during the cooling stages followed heating ageing are also showed in Figs.3a and b (partial temperature points), respectively)

Table 1 Properties of 7055 aluminum alloy under different ageing states

Fig.4 The exfoliation corrosion morphologies of ageing states of T6 (a), T73 (b), 1/215/L (c), 3/225/L (d) and RRA (e)
Color online

Fig.5 TEM images and selected area electrom diffraction SAED patterns of the precipitates in the grain under ageing states of T6 (a), T73 (b), 1/215/L (c), 3/225/L (d), RRA (e) (The SAED patterns are shown at the upper right corners. The insets at the lower left corner in Figs.5a, b and e are the schematics of diffraction patterns along [001]_Al, and these in Figs.5c and d are the schematics of diffraction patterns along <112>_Al)

Fig.6 TEM images of grain boundary after ageing treated of T6 (a), T73 (b), 1/215/L (c), 3/225/L (d) and RRA (e)

Fig.7 TEM images and SAED patterns (insets) of the first ageing state and the precipitates formed during the heating ageing process (3 ℃/min)
Color online
(a) the first stage of 105 ℃, 24 h (The inset at the lower left corner is the schematic of SAED pattern along <112>_Al)
(b) heating the sample to 176 ℃ at 3 ℃/min and water cooling to room temperature (3/176/S)
(c) heating the sample to 207 ℃ at 3 ℃/min and water cooling to room temperature (3/207/S)
(d) heating the sample to 225 ℃ at 3 ℃/min and water cooling to room temperature (3/225/S)

Fig.8 DSC curves of the samples at the different heating temperatures (heating rate is 3 ℃/min. 3 represents the heating rate of 3 ℃/min. 130, 176, 207 and 225 are the different heating temperatures during the heating process. S represents water cooling treatment. The arrow indicates the movement of dissolution temperature to higher level because the precipitates became more and more thermal stable during the heating process)

Fig.9 DSC curves of the samples under different cooling temperature (T_p=225 ℃. 164 and 25 are the different temperatures during the cooling process. C represents the cooling ageing. The arrow indicates the movement of dissolution temperature to lower level because the secondary precipitation occurred during cooling)

[1]	Azarniya A, Taheri A K, Taheri K K. Recent advances in ageing of 7xxx series aluminum alloys: A physical metallurgy perspective [J]. J. Alloys Compd., 2019, 781: 945
[2]	Li S, Dong H G, Li P, et al. Effect of repetitious non-isothermal heat treatment on corrosion behavior of Al-Zn-Mg alloy [J]. Corros. Sci., 2018, 131: 278
[3]	Lin Y C, Zhang J L, Chen M S. Evolution of precipitates during two-stage stress-aging of an Al-Zn-Mg-Cu alloy [J]. J. Alloys Compd., 2016, 684: 177
[4]	Jiang J T, Tang Q J, Yang L, et al. Non-isothermal ageing of an Al-8Zn-2Mg-2Cu alloy for enhanced properties [J]. J. Mater. Process. Technol., 2016, 227: 110
[5]	Sun Y S, Jiang F L, Zhang H, et al. Residual stress relief in Al-Zn-Mg-Cu alloy by a new multistage interrupted artificial aging treatment [J]. Mater. Des., 2016, 92: 281
[6]	Moghanaki S K, Kazeminezhad M. Effects of non-isothermal annealing on microstructure and mechanical properties of severely deformed 2024 aluminum alloy [J]. Trans. Nonferrous Met. Soc. China, 2017, 27: 1
[7]	Hayoune A, Hamana D. Structural evolution during non-isothermal ageing of a dilute Al-Cu alloy by dilatometric analysis [J]. J. Alloys Compd., 2009, 474: 118
[8]	Yazdanmehr M, Bahrami A, Anijdan S H M. A precipitation-hardening model for non-isothermal ageing of Al-Mg-Si alloys [J]. Comput. Mater. Sci., 2009, 45: 385
[9]	Guo M X, Zhang Y, Zhang X K, et al. Non-isothermal precipitation behaviors of Al-Mg-Si-Cu alloys with different Zn contents [J]. Mater. Sci. Eng., 2016, A669: 20
[10]	Zhang X. Study on the microstructure evolution of 7050 aluminum alloy during non-isothermal aging process [D]. Harbin: Harbin Institute of Technology, 2012
	(张雪. 7050铝合金非等温时效过程组织演变研究 [D]. 哈尔滨: 哈尔滨工业大学, 2012)
[11]	Lin Y, Jiang D M, Li B Q, et al. Heating aging behavior of Al-8.35Zn-2.5Mg-2.25Cu alloy [J]. Mater. Des., 2014, 60: 116
[12]	Tang Q J. Study on cooling ageing process of 7A85 aluminum alloy [D]. Harbin: Harbin Institute of Technology, 2010
	(唐秋菊. 7A85铝合金降温时效工艺的研究 [D]. 哈尔滨: 哈尔滨工业大学, 2010)
[13]	Jiang D M, Liu Y, Liang S, et al. The effects of non-isothermal aging on the strength and corrosion behavior of Al-Zn-Mg-Cu alloy [J]. J. Alloys Compd., 2016, 681: 57
[14]	Liu Y, Jiang D M, Li B Q, et al. Effect of cooling aging on microstructure and mechanical properties of an Al-Zn-Mg-Cu alloy [J]. Mater. Des., 2014, 57: 79
[15]	Koziel J, Blaz L, Wloch G, et al. Precipitation processes during non-isothermal aging of fine-grained AA2219 [J]. J. Alloys Compd., 2016, 682: 468
[16]	Liu Y, Liang S, Jiang D M. Influence of repetitious non-isothermal aging on microstructure and strength of Al-Zn-Mg-Cu alloy [J]. J. Alloys Compd., 2016, 689: 632
[17]	Li J C, Feng D, Xia W S, et al. Effect of non-isothermal aging on microstructure and properties of 7B50 aluminum alloy [J]. Acta Metall. Sin., 2020, 46: 1255
	(李吉臣, 冯迪, 夏卫生等. 非等温时效对7B50铝合金组织及性能的影响 [J]. 金属学报, 2020, 46: 1255)
[18]	Feng D, Zhang X M, Chen H M, et al. Effect of non-isothermal retrogression and re-ageing on microstructure and properties of Al-8Zn-2Mg-2Cu alloy thick plate [J]. Acta Metall. Sin., 2018, 54: 100
	(冯迪, 张新明, 陈洪美等. 非等温回归再时效对Al-8Zn-2Mg-2Cu合金厚板组织及性能的影响 [J]. 金属学报, 2018, 54: 100)
[19]	Engdahl T, Hansen V, Warren P J, et al. Investigation of fine scale precipitates in Al-Zn-Mg alloys after various heat treatments [J]. Mater. Sci. Eng., 2002, A327: 59
[20]	Sha G, Cerezo A. Early-stage precipitation in Al-Zn-Mg-Cu alloy (7050) [J]. Acta Mater., 2004, 52: 4503
[21]	Li L, Wei L J, Xu Y J, et al. Study on the optimizing mechanisms of superior comprehensive properties of a hot spray formed Al-Zn-Mg-Cu alloy [J]. Mater. Sci. Eng., 2019, A742: 102
[22]	Berg L K, Gjønnes J, Hansen V, et al. GP-zones in Al-Zn-Mg alloys and their role in artificial aging [J]. Acta Mater., 2001, 49: 3443
[23]	Mazzer E M, Afonso C R M, Galano M, et al. Microstructure evolution and mechanical properties of Al-Zn-Mg-Cu alloy reprocessed by spray-forming and heat treated at peak aged condition [J]. J. Alloys Compd., 2013, 579: 169
[24]	Liu L L, Pan Q L, Wang X D, et al. The effects of aging treatments on mechanical property and corrosion behavior of spray formed 7055 aluminium alloy [J]. J. Alloys Compd., 2018, 735: 261
[25]	Ozer G, Karaaslan A. Properties of AA7075 aluminum alloy in aging and retrogression and reaging process [J]. Trans. Nonferrous Met. Soc. China, 2017, 27: 2357
[26]	Ranganatha R, Kumar V A, Nandi V S, et al. Multi-stage heat treatment of aluminum alloy AA7049 [J]. Trans. Nonferrous Met. Soc. China, 2013, 23: 1570
[27]	Marlaud T, Deschamps A, Bley F, et al. Evolution of precipitate microstructures during the retrogression and re-ageing heat treatment of an Al-Zn-Mg-Cu alloy [J]. Acta Mater., 2010, 58: 4814
[28]	Viana F, Pinto A M P, Santos H M C, et al. Retrogression and re-ageing of 7075 aluminium alloy: Microstructural characterization [J]. J. Mater. Process. Technol., 1999, 92-93: 54
[29]	Chen J Z. Ageing precipitation behavior and mechanical properties of AA 7055 aluminum alloy [D]. Harbin: Harbin Institute of Technology, 2008
	(陈军洲. AA 7055铝合金的时效析出行为与力学性能 [D]. 哈尔滨: 哈尔滨工业大学, 2008)
[30]	Nicolas M, Deschamps A. Characterisation and modelling of precipitate evolution in an Al-Zn-Mg alloy during non-isothermal heat treatments [J]. Acta Mater., 2003, 51: 6077 doi: 10.1016/S1359-6454(03)00429-4
[31]	Liu D M, Xiong B Q, Bian F G, et al. In situ studies of microstructure evolution and properties of an Al-7.5Zn-1.7Mg-1.4Cu-0.12Zr alloy during retrogression and reaging [J]. Mater. Des., 2014, 56: 1020 doi: 10.1016/j.matdes.2013.12.006
[32]	Liu D M, Xiong B Q, Bian F G, et al. Quantitative study of precipitates in an Al-Zn-Mg-Cu alloy aged with various typical tempers [J]. Mater. Sci. Eng., 2013, A588: 1
[33]	Nandana M S, Bhat K U, Manjunatha C M. Influence of retrogression and re-ageing heat treatment on the fatigue crack growth behavior of 7010 aluminum alloy [J]. Procedia Struct. Integr., 2019, 14: 314

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