Influence of Deep Cryogenic Treatment on Microstructure and Properties of 7A99 Ultra-High Strength Aluminum Alloy
Abstract
:1. Introduction
2. Materials and Methods
3. Experimental Results
3.1. Tensile Properties
3.2. Microstructures
4. Discussion
5. Conclusions
- (1)
- The tensile strength, tensile yield strength, and elongation of the T6-DCT-treated 7A99 alloy are 6 MPa, 19 MPa, and 3% higher, respectively, than those of the T6-treated alloy.
- (2)
- The grain size of the T6-DCT-treated 7A99 aluminum alloy is slightly smaller and more uniform than that of the T6-treated alloy. The matrix precipitates of the T6-DCT-treated alloy transform from a single phase (η’-MgZn2) into two phases (η’-MgZn2 and η-MgZn2). Compared with those in the T6-treated alloy, the precipitates are smaller and are more uniformly distributed.
- (3)
- After the T6-DCT process, the segregation degree of Zn, Mg, and Cu elements decreases, the fraction of clusters with sizes of 10–20 nm and 20–50 nm increases, whereas the fraction of clusters with sizes of >1000 nm decreases.
- (4)
- DCT accelerates the precipitation process, refines the precipitates, and increases the uniformity of the precipitate distribution, thereby resulting in improved strength and elongation of the T6-DC-treated 7A99 alloy.
Author Contributions
Funding
Conflicts of Interest
References
- Heinz, A.; Haszler, A.; Keidel, C.; Moldenhauer, S.; Benedictus, R.; Miller, W.S. Recent development in aluminum alloys for aerospace applications. Mater. Sci. Eng. A 2000, 280, 102–107. [Google Scholar] [CrossRef]
- Chen, S.Y.; Chen, K.H.; Peng, G.S.; Chen, X.H.; Ceng, Q.H. Effect of heat treatment on hot deformation behavior and microstructure evolution of 7085 aluminum alloy. J. Alloys Compd. 2012, 537, 338–345. [Google Scholar] [CrossRef]
- Zhang, X.M.; Tan, Q.; Liu, S.D.; Wu, Y.L.; Song, F.X.; Liu, X.X. Effect of quenching rate on aging behavior of 7085 aluminum alloy. Trans. Nonferrous Met. Soc. China 2014, 24, 870–877. [Google Scholar]
- Liu, B.; Peng, C.Q.; Wang, R.C.; Wang, X.F.; Li, T.T. Recent development and prospects for giant plane aluminum alloys. Trans. Nonferrous Met. Soc. China 2010, 20, 1705–1715. [Google Scholar]
- Warner, T. Recently-developed aluminum solutions for aerospace applications. Mater. Sci. Forum 2006, 519–521, 1271–1278. [Google Scholar] [CrossRef]
- Nie, B.H.; Liu, P.Y.; Zhou, T.T. Effect of compositions on the quenching sensitivity of 7050 and 7085 alloys. Mater. Sci. Eng. A 2016, 667, 106–107. [Google Scholar] [CrossRef]
- Liu, S.D.; Li, C.B.; Han, S.Q.; Deng, Y.L.; Zhang, X.M. Effect of natural aging on quench-induced inhomogeneity of microstructure and hardness in high strength 7055 aluminum alloy. Mater. Sci. Eng. A 2015, 625, 34–35. [Google Scholar] [CrossRef]
- Yu, H.C.; Wang, M.P.; Sheng, X.F.; Li, Z.; Chen, L.B.; Lei, Q.; Chen, C.; Jia, Y.L.; Xiao, Z.; Chen, W.; et al. Microstructure and tensile properties of large-size 7055 aluminum billets fabricated by spray forming rapid solidification technology. J. Alloys Compd. 2013, 578, 208–214. [Google Scholar] [CrossRef]
- Xie, X.; Wu, X.C.; Min, N.; Shen, Y.L. Carbon Segregation Behavior of high carbon high-alloy steel during deep cryogenic treatment using 3DAP. Acta Metall. Sin. 2015, 3, 325–326. [Google Scholar]
- Wang, J.; Fu, R.D.; Li, Y.J.; Zhang, J.F. Effects of deep cryogenic treatment and low-temperature aging on the mechanical properties of friction-stir-welded joints of 2024-T351 aluminum alloy. Mater. Sci. Eng. A 2014, 609, 147–148. [Google Scholar] [CrossRef]
- Wu, H.Y.; Ai, Z.R.; Liu, X.H. Progress of research and application on cryogenic treatment of steels. Trans. Mater. Heat Treat. 2013, 34, 1–6. [Google Scholar]
- Wang, K.K.; Tan, Z.L.; Gu, K.X.; Gao, B.; Gao, G.H.; Misra, R.D.K.; Bai, B.Z. Effect of deep cryogenic treatment on structure-property relationship in an ultrahigh strength Mn-Si-Cr bainite/martensite multiphase rail steel. Mater. Sci. Eng. A 2017, 684, 559–566. [Google Scholar] [CrossRef]
- Li, H.Z.; Tong, W.P.; Cui, J.J.; Zhang, H.; Chen, L.Q.; Zuo, L. The influence of deep cryogenic treatment on the properties of high-vanadium alloy steel. Mater. Sci. Eng. A 2016, 662, 356–362. [Google Scholar] [CrossRef]
- Li, G.R.; Wang, H.M.; Yan, X.T.; Cai, Y.; Zhao, Y.T.; Wang, J.J. Structure evolution and properties of 7055Aluminum alloy with cycle cryogenic treatment. Rare Met. Mater. Eng. 2013, 42, 251–254. [Google Scholar]
- Chen, D.; Li, W.X. Cryogenic treatment of Al and Al alloys. Trans. Nonferrous Met. Soc. China 2000, 10, 891–895. [Google Scholar]
- Asl, K.M.; Tari, A.; Khomamizadeh, F. Effect of deep cryogenic treatment on microstructure, creep and wear behaviors of AZ91 magnesium alloy. Mater. Sci. Eng. A 2009, 523, 27–31. [Google Scholar] [CrossRef]
Zn | Mg | Cu | Zr | Ti | Fe | Si | Be |
---|---|---|---|---|---|---|---|
7.6–8.6 | 1.7–2.5 | 1.4–2.0 | 0.1–0.20 | 0.02–0.05 | ≤0.08 | ≤0.06 | ≤0.002 |
Tm/°C | Tp/°C | Tc/°C | λ | Vs/mm/min |
---|---|---|---|---|
400 ± 10 | 400 | 400 | 12:1 | 0.2 |
Parameters | Quenching | Aging Treatment | ||||||
---|---|---|---|---|---|---|---|---|
Cycle 1 | Cycle 2 | Cycle 3 | Subsequent Aging | |||||
Temperature (°C) | 473 | −120 | 120 | −120 | 120 | −120 | 120 | 120 |
Time (h) | 4 | 0.1 | 2 | 0.1 | 4 | 0.1 | 4 | 14 |
Heading | T6 | T6-DCT | Increasing Value |
---|---|---|---|
UTS (MPa) | 699 ± 0.8 | 705 ± 1 | 6 |
TYS (MPa) | 659 ± 1.4 | 678 ± 1.6 | 19 |
Elongation (%) | 11 ± 0.4 | 14 ± 0.6 | 3 |
© 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
Share and Cite
Gao, W.; Wang, X.; Chen, J.; Ban, C.; Cui, J.; Lu, Z. Influence of Deep Cryogenic Treatment on Microstructure and Properties of 7A99 Ultra-High Strength Aluminum Alloy. Metals 2019, 9, 631. https://doi.org/10.3390/met9060631
Gao W, Wang X, Chen J, Ban C, Cui J, Lu Z. Influence of Deep Cryogenic Treatment on Microstructure and Properties of 7A99 Ultra-High Strength Aluminum Alloy. Metals. 2019; 9(6):631. https://doi.org/10.3390/met9060631
Chicago/Turabian StyleGao, Wenlin, Xiangjie Wang, Junzhou Chen, Chunyan Ban, Jianzhong Cui, and Zheng Lu. 2019. "Influence of Deep Cryogenic Treatment on Microstructure and Properties of 7A99 Ultra-High Strength Aluminum Alloy" Metals 9, no. 6: 631. https://doi.org/10.3390/met9060631