Precipitation Strengthening Model of AA 7055 Aluminium Alloy

doi:10.11900/0412.1961.2020.00328

Acta Metall Sin

2021, Vol. 57

Issue (3): 353-362 DOI: 10.11900/0412.1961.2020.00328

Research paper

Current Issue | Archive | Adv Search

Precipitation Strengthening Model of AA 7055 Aluminium Alloy

CHEN Junzhou¹^,²(

), LV Liangxing³, ZHEN Liang³, DAI Shenglong¹^,²

^1.AECC Beijing Institute of Aeronautical Materials, Beijing 100095, China
^2.Beijing Engineering Research Center of Advanced Aluminum Alloys and Applications, Beijing 100095, China
^3.School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China

Cite this article:

CHEN Junzhou, LV Liangxing, ZHEN Liang, DAI Shenglong. Precipitation Strengthening Model of AA 7055 Aluminium Alloy. Acta Metall Sin, 2021, 57(3): 353-362.

Download:

HTML

PDF(2077KB)
Export: BibTeX | EndNote (RIS)

Abstract

AA 7055 aluminium alloy has been widely applied in aviation and aerospace applications, especially after T7751 heat treatment, owing to its excellent properties, such as high strength and good stress corrosion and fatigue resistances. For 7XXX aluminium alloys, aging hardening is the main strengthening mechanism, and the hardening effect is determined by the microstructural features of precipitates including morphology, composition, volume fraction, nucleation density, and size distribution. To further improve the property of alloy and expand the breadth of applications, establishing a precise predictive model regarding strength performance associated with the precipitates is necessary. In this work, based on the quantitative results of the precipitates obtained using small angle X-ray scattering techniques, the strengthening models of AA 7055 Al alloys aged at 120 and 160^oC were investigated. Precipitation kinetics show that at the early stages of aging, the evolution of radius and the half thickness of plate-like precipitates are both linear with t^1/2 (t means the aging time). Conversely, at the later stages of aging, they are linear with t^1/3. The evolution of the volume fraction of the precipitates follows a JMA (Johnson-Mehl-Avrami)-type equation. Strength contributions from both GPI zones and η' precipitates are considered. Moreover, strengthening modeling considered both the modulus and coherency strain strengthening mechanisms of these two kinds of precipitates that had been built for the AA 7055 Al alloy aged at 120 and 160^oC. Therefore, yield strength during aging can be predicted.

Key words: AA 7055 aluminium alloy aging precipitation strengthening model

Received: 26 August 2020

ZTFLH:

TG146.2

	Service

	E-mail this article
	Add to citation manager
	E-mail Alert
	RSS
	（）
	Articles by authors
	Junzhou CHEN
	Liangxing LV
	Liang ZHEN
	Shenglong DAI

URL:

https://www.ams.org.cn/EN/10.11900/0412.1961.2020.00328 OR https://www.ams.org.cn/EN/Y2021/V57/I3/353

Fig.1 Schematic of tensile samples (unit: mm)

Fig.2 Diagrams of r² and h²vs aging time (t) for the AA 7055 Al alloy (r—radius of precipitate, h—half thickness of precipitate)

Fig.3 Diagrams of r³ and h³vst for the AA 7055 Al alloy

Fig.4 Evolutions of volume fraction of precipitates (f_p)vs t for the AA 7055 Al alloy during aging

Fig.5 Yield strength from the experiment compared with the predicted value using over-aged model (Eq.(40)) for the AA 7055 Al alloy aged at 160^oC

Fig.6 Evolution of the volume fraction of GPI zones (f_GPI) for the AA 7055 Al alloy aged at 160^oC for different time

Fig.7 Contributions of various precipitates to the yield strength for the under-aged AA 7055 Al alloy aged at 160^oC

Fig.8 Yield strength from the experiment compared with the predicted value using under-aged model (Eq.(42)) for the AA 7055 Al alloy aged at 160^oC

Fig.9 Yield strength from the experiment compared with the model predicted (Eq.(43)) for the AA 7055 Al alloy aged at 160^oC

Fig.10 Yield strength from the experiment compared with the predicted value using over-aged model (Eq.(40)) for the AA 7055 Al alloy aged at 120^oC

Parameter	Value	Data source
Taylor factor M	3.06	Present model
Coherency strain for η'ε_η'	0.0133	Present model
Coherency strain for GPI ε_GPI	0.0025	Present model
Constant depends on the precipitation κ	3.2	Present model
Maximum volume fraction of whole precipitation $f m a x$	0.1035	Ref.[13]
Maximum volume fraction of the GPI zone $f m a x, ? G P I$	0.025	Present model
Shear modulus G	27 GPa	Ref.[25]
Shear modulus between the η' and matrix ΔE_η'	0.7 GPa	Ref.[26]
Shear modulus between the GPI zones and matrix ΔE_GPI	1.5 GPa	Present model
Inherent strength of Al σ_i	15.7 MPa	Ref.[27]
Grain boundary strengthening value Δσ_GB	22 MPa	Present model
Constant depends on the solute atoms C₃	237.5 MPa	Present model
Magnitude of the Burgers vector b	0.286 nm	Ref.[25]

Table 1 Summaries of input data using under-aged model for the AA 7055 Al alloy aged at 120^oC

Fig.11 Evolution of the f_GPI for the AA 7055 Al alloy aged at 120^oC

Fig.12 Contributions of various precipitates to the yield strength for the AA 7055 Al alloy aged at 120^oC

Fig.13 Yield strength from the experiment compared with the predicted value using under-aged model (Eq.(46)) for the AA 7055 Al alloy aged at 120^oC

1	Williams J C, Starke Jr E A. Progress in structural materials for aerospace systems [J]. Acta Mater., 2003, 51: 5775
2	Deschamps A, Livet F, Bréchet Y. Influence of predeformation on ageing in an Al-Zn-Mg alloy-I. Microstructure evolution and mechanical properties [J]. Acta Mater., 1998, 47: 281
3	Liu J. Advanced aluminium and hybrid aerostructures for future aircraft [J]. Mater. Sci. Forum, 2006, 519-521: 1233
4	Cong F G, Zhao G, Tian N, et al. Research progress and development trend of strengthening-toughening of ultra-high strength 7XXX aluminum alloy [J]. Light Alloy Fabr. Technol., 2012, 40(10): 23
	丛福官, 赵刚, 田妮等. 7XXX系超高强铝合金的强韧化研究进展及发展趋势 [J]. 轻合金加工技术, 2012, 40(10): 23
5	Du Z W, Sun Z M, Shao B L, et al. Quantitative evaluation of precipitates in an Al-Zn-Mg-Cu alloy after isothermal aging [J]. Mater. Charact., 2006, 56: 121
6	Deschamps A, Bréchet Y. Influence of predeformation and ageing of an Al-Zn-Mg alloy-II. Modeling of precipitation kinetics and yield stress [J]. Acta Mater., 1998, 47: 293
7	Starink M J, Wang P, Sinclair I, et al. Microstructure and strengthening of Al-Li-Cu-Mg alloys and MMCS: II. Modelling of yield strength [J]. Acta Mater., 1999, 47: 3855
8	Starink M J, Wang S C. A model for the yield strength of overaged Al-Zn-Mg-Cu alloys [J]. Acta Mater., 2003, 51: 5131
9	Liu G, Zhang G J, Ding X D, et al. Modeling the strengthening response to aging process of heat-treatable aluminum alloys containing plate/disc- or rod/needle-shaped precipitates [J]. Mater. Sci. Eng., 2003, A344: 113
10	Chen J Z, Lv L X, Zhen L, et al. Quantitative characterization on the precipitation of AA 7055 Aluminum Alloy by SAXS [J]. Acta. Metall. Sin., 2017, 53: 897
	陈军洲, 吕良星, 甄良等. AA 7055铝合金时效析出过程的小角度X射线散射定量表征 [J]. 金属学报, 2017, 53: 897
11	Liu G. Modeling and experimental investigation into the mechanical properties of aged aluminum alloys containing multi-scaled second phase particles [D]. Xi'an: Xi'an Jiao Tong University, 2002
	刘刚. 含多尺度第二相时效铝合金力学性能的模型化与实验研究 [D]. 西安: 西安交通大学, 2002
12	Russell K C. Nucleation in solids: The induction and steady state effects [J]. Adv. Colloid Interface Sci., 1980, 13: 205
13	Werenskiold J C, Deschamps A, Bréchet Y. Characterization and modeling of precipitation kinetics in an Al-Zn-Mg alloy [J]. Mater. Sci. Eng., 2000, A293: 267
14	Horvay G, Cahn J W. Dendritic and spheroidal growth [J]. Acta Metall., 1961, 9: 695
15	Ferrante M, Doherty R D. Influence of interfacial properties on the kinetics of precipitation and precipitate coarsening in aluminium-silver alloys [J]. Acta Metall., 1979, 27: 1603
16	Davies C K L, Nash P, Stevens R N. The effect of volume fraction of precipitate on Ostwald ripening [J]. Acta Metall., 1980, 28: 179
17	Feng D. Physics of Metals. Volume II Phase Transition [M]. Beijing: Science Press, 1990: 150
	冯端. 金属物理学. 第二卷相变 [M]. 北京: 科学出版社, 1990: 150
18	Shercliff H R, Ashby M F. A process model for age hardening of aluminium alloys-I. The model [J]. Acta Metall. Mater., 1990, 38: 1789
19	Du Z W. Precipitation and strengthening of 7000 serials and their Li containing aluminum alloys [D]. Beijing: Beihang University, 2005
	杜志伟. Al-Zn-Mg-Cu及其含Li合金沉淀析出过程显微结构演化的研究 [D]. 北京: 北京航空航天大学, 2005
20	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
21	Sha G, Cerezo A. Early-stage precipitation in Al-Zn-Mg-Cu alloy (7050) [J]. Acta Mater., 2004, 52: 4503
22	Yang D Z. Dislocations and Strengthening Mechanisms of Metals [M]. Harbin: Harbin Institute of Technology Press, 1991: 178
	杨德庄. 位错与金属强化机制 [M]. 哈尔滨: 哈尔滨工业大学出版社, 1991: 178
23	Zhu A W, Starke Jr E A. Strengthening effect of unshearable particles of finite size: A computer experimental study [J]. Acta Mater., 1999, 47: 3263
24	Chen J Z, Zhen L, Yang S J, et al. Investigation of precipitation behavior and related hardening in AA 7055 aluminum alloy [J]. Mater. Sci. Eng., 2009, A500: 34
25	Song M. Modeling the hardness and yield strength evolutions of aluminum alloy with rod/needle-shaped precipitates [J]. Mater. Sci. Eng., 2007, A443: 172
26	Seidenkranz T, Hegenbarth E. Single-crystal elastic constants of MgZn₂ in the temperature range from 4.2 to 300 K [J]. Phys. Stat. Sol., 1976, 33A: 205
27	Spriano S, Doglione R, TextureBaricco M., hardening and mechanical anisotropy in AA8090-T851 plate [J]. Mater. Sci. Eng., 1998, A257: 134

[1]	WANG Changsheng, FU Huadong, ZHANG Hongtao, XIE Jianxin. Effect of Cold-Rolling Deformation on Microstructure, Properties, and Precipitation Behavior of High-Performance Cu-Ni-Si Alloys[J]. 金属学报, 2023, 59(5): 585-598.
[2]	GONG Xiangpeng, WU Cuilan, LUO Shifang, SHEN Ruohan, YAN Jun. Effect of Natural Aging on Artificial Aging of an Al-2.95Cu-1.55Li-0.57Mg-0.18Zr Alloy at 160^oC[J]. 金属学报, 2023, 59(11): 1428-1438.
[3]	YANG Wenchao WANG Mingpu SHENG Xiaofei ZHANG Qian WANG Zheng’an. STUDY OF THE AGING PRECIPITATION AND HARDENING BEHAVIOR OF 6005A ALLOY SHEET FOR RAIL TRAFFIC VEHICLE[J]. 金属学报, 2010, 46(12): 1481-1487.
[4]	. The Influence of the Aging on the Mechanical Property of a Drawn Pearlite Steel[J]. 金属学报, 2006, 42(10): 1009-1013 .

No Suggested Reading articles found!

Viewed

Full text

Abstract

Cited

Shared

Discussed