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金属学报  2017, Vol. 53 Issue (9): 1110-1124    DOI: 10.11900/0412.1961.2016.00547
  本期目录 | 过刊浏览 |
Al-7Si-Mg铝合金拉伸过程应变硬化行为及力学性能模拟研究
陈瑞1, 许庆彦1(), 郭会廷2, 夏志远2, 吴勤芳2, 柳百成1
1 清华大学材料学院先进成形制造教育部重点实验室 北京 100084
2 明志科技有限公司 苏州 215006
Modeling of Strain Hardening Behavior and Mechanical Properties of Al-7Si-Mg Cast Aluminum AlloysDuring Tensile Process
Rui CHEN1, Qingyan XU1(), Huiting GUO2, Zhiyuan XIA2, Qinfang WU2, Baicheng LIU1
1 Key Laboratory for Advanced Materials Processing Technology (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
2 Mingzhi Technology Co. Ltd., Suzhou 215006, China
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摘要: 

建立了时效析出动力学模型、强化模型以及应变硬化模型,针对Al-7Si-Mg合金开展拉伸性能模拟研究。时效析出动力学模型可以模拟析出相密度、尺寸、分布、体积分数、基体中元素含量等微观组织参数,并结合强化模型获得合金的屈服强度。通过应变硬化模型可模拟合金在拉伸过程的应力-应变曲线,并结合关系式(σUTSY)=Y+n+f (Tss)获得合金的抗拉强度和延伸率。本工作首先模拟了Al-7Si-0.4Mg合金的析出相特征参数及屈服强度并进行实验验证,分析了模拟结果与实验结果之间存在偏差的可能原因。采用应变硬化模型模拟了Al-7Si-0.36Mg合金在拉伸过程的应力-应变曲线,分析时效处理和铸态组织细化程度对位错存储速率、动态回复速率及合金的应力-应变曲线的影响规律。采用本模型预测了Al-7Si-0.4Mg合金在不同时效温度下的抗拉强度和延伸率,并与实验结果进行对比,分析了二次枝晶臂间距对拉伸性能的影响。最后,对模型存在的局限性及影响拉伸性能预测精度的因素进行了分析。

关键词 Al-7Si-Mg铝合金  拉伸性能  应变硬化 析出相 时效处理  模拟    
Abstract

Al-7Si-Mg alloy castings have extensive applications in automotive industries, and the tensile properties of these alloys including yield strength, ultimate tensile strength and elongation are commonly used to judge their mechanical properties. In this work, the modified precipitation kinetics model, yield strength model and strain hardening model have been proposed to predict the tensile properties of Al-7Si-Mg alloys. The precipitation kinetics model can be used to predict the precipitate microstructure parameters including the precipitate density, size, size distribution, volume fraction, and composition and so on in these alloys, combining which with the strength model, their yield strengths can be obtained. The strain hardening model can be applied to simulate the stress-strain curves during tensile process, and the ultimate tensile strengths and elongations can be obtained by combining this model with the experimental data fitted with the expression (σUTSY)=Y+n+f (Tss). First, the evolution of precipitate microstructure parameters and yield strengths as a function of ageing time were simulated, and then their comparisons with the experimental results were performed. The possible reasons resulting in the deviations between simulated and experimental yield strengths were analyzed. The stress-strain curves during tensile process of Al-7Si-0.36Mg alloy were simulated using strain hardening model, and the influences of ageing treatment and as-cast microstructure refining scale on the parameters of dislocation storage rate, dynamic recovery rate and the stress-strain curves were analyzed. Then, the ultimate tensile strengths and elongations of Al-7Si-0.4Mg alloy aged at different temperatures were predicted which are in better agreement with the experimental results, and the influence of secondary dendrite arm spacing on tensile properties was also analyzed. Finally, the limitation of present model and the factors influencing the prediction precision of tensile properties were outlined.

Key wordsAl-7Si-Mg alloy    tensile property    strain hardening    precipitate    ageing treatment    modeling
收稿日期: 2016-12-05      出版日期: 2017-06-08
ZTFLH:  TG146.2  
基金资助: 国家重点基础研究发展计划项目No.2011CB706801及国家自然科学基金项目Nos.51374137和51171089
作者简介:

作者简介 陈瑞,男,1989年生,博士生

引用本文:

陈瑞, 许庆彦, 郭会廷, 夏志远, 吴勤芳, 柳百成. Al-7Si-Mg铝合金拉伸过程应变硬化行为及力学性能模拟研究[J]. 金属学报, 2017, 53(9): 1110-1124.
Rui CHEN, Qingyan XU, Huiting GUO, Zhiyuan XIA, Qinfang WU, Baicheng LIU. Modeling of Strain Hardening Behavior and Mechanical Properties of Al-7Si-Mg Cast Aluminum AlloysDuring Tensile Process. Acta Metall Sin, 2017, 53(9): 1110-1124.

链接本文:

http://www.ams.org.cn/CN/10.11900/0412.1961.2016.00547      或      http://www.ams.org.cn/CN/Y2017/V53/I9/1110

图1  Al-7Si-Mg合金拉伸过程工程应力-工程应变曲线及硬化速率随应力变化示意图
图2  Al-7Si-Mg合金的Young's模量随屈服强度的变化曲线
图3  片状和棒状拉伸试样的几何尺寸
Sample shape ST temperature ST time Ageing Ageing
h temperature / ℃ time / h
Cylindrical 550 2 200 0~36
Cylindrical 550 2 180 0~72
Cylindrical 550 2 160 0~120
Cylindrical 535 2 180 0~72
Plat 550 2 180 0~72
表1  拉伸试样采用的固溶及时效工艺方案
图4  Al-7Si-0.4Mg合金在180 ℃时效不同时间后的TEM和HRTEM像
图5  Al-7Si-0.4Mg合金在160和180 ℃下随时效时间的拉伸性能
图6  不同热处理条件下及在180 ℃不同二次枝晶臂间距(d)条件下Al-7Si-0.36Mg合金(σUTS-σY)随σY的变化规律
Ageing temperature / ℃ Ageing time / h Mean radius / nm Mean aspect ratio
160 8 1.46±0.167 7.4±2.12
160 24 1.76±0.188 7.8±2.31
160 120 1.91±0.290 8.0±3.08
180 0.33 1.07±0.085 -
180 1 1.40±0.240 7.1±2.20
180 4 1.75±0.271 7.5±2.88
180 24 2.01±0.320 7.8±2.36
180 120 2.28±0.274 6.8±1.98
200 2 1.89±0.274 8.2±3.16
表2  Al-7Si-0.4Mg合金在不同时效工艺下的析出相平均半径和长径比
Parameter Unit Value
Atomic fraction of Mg in β" precipitate xMgβ % 5/11[36]
Atomic fraction of Si in β" precipitate xSiβ % 6/11[36]
Aspect ratio of precipitate ? - 7
Interface energy γ Jm-2 0.35[38]
Shear modulus of matrix G Nm-2 2.7×1010[7]
Magnitude of the burgers vector b m 2.84×10-10[7]
Taylor factor M - 3.1[7]
Precipitate Young's modulus Ep GPa 59[16]
Ratio of volume fraction of matrix and β" precipitate ω - 1
Factor for adjusting the effective diffusion distance ξ - 1
Constant depends on the shape and nature of dislocation δ - 0.25[39]
Precipitate shearing/bypassing transition radius rpc nm 2.4
Precipitate coherency/incoherency transition radius rcl nm 4.0
Maximum number of loops around a precipitate np* - 9[16]
Parameter associated with the rate of dislocation storage k1 m-1 Varying
Parameter associated with the rate of dynamic recovery k20 - Varying
Parameter associated with dislocation loop k2p - 600
表3  Al-7Si-Mg合金拉伸性能和应力-应变曲线计算所用的参数
图7  3组时效温度下Al-7Si-0.4Mg合金析出相密度和半径随时效时间的变化
图8  Al-7Si-0.4Mg合金在3组时效温度下的屈服强度模拟结果与实验结果对比
Ageing time / h xMgα / % k1 / m-1 k20 θ0 / MPa%-1 K
0 0.400 1.65 13 14.6 0.175
0.5 0.363 2.10 14 20.2 0.185
1 0.268 2.65 20 25.8 0.273
2 0.083 2.65 26 26.1 0.359
4 0.008 2.65 28 25.5 0.377
8 0.007 2.65 39 23.8 0.496
12 0.006 2.65 42 25.1 0.575
24 0.005 2.65 42 23.7 0.564
表4  180 ℃时效条件下基体中xMgα∞,k1,k20,θ0和K随时效时间的变化
图9  Al-7Si-0.36Mg合金(d=24.9 μm)在180 ℃时效不同时间后的应力-应变曲线实验和模拟结果对比
图10  Al-7Si-0.36Mg合金中晶界和共晶硅颗粒所引起的随动硬化效果Δσkin_e对合金应力-应变曲线(σ-σY~ε-εY)以及硬化速率的影响
d / μm k1 / m-1 k20 D / μm
53.2 2.38 26 5.8
43.0 2.46 26 5.5
36.7 2.55 26 5.0
24.9 2.65 26 5.0
表5  计算不同二次枝晶臂间距试样的应力-应变曲线时所采用的参数k1、k20和D
图11  二次枝晶臂间距对Al-7Si-0.36Mg合金拉伸过程的应力-应变曲线和硬化速率的影响
图12  Al-7Si-0.4Mg合金拉伸试样在160和180 ℃下时效0~36 h的工程应力-工程应变曲线模拟结果以及抗拉强度和延伸率的模拟结果和实验值的比较
图13  不同二次枝晶臂间距的Al-7Si-0.4Mg合金拉伸试样在180 ℃时效0~24 h的屈服强度、抗拉强度和延伸率模拟结果
[1] Y?ld?r?m M, ?zyürek D.The effects of Mg amount on the microstructure and mechanical properties of Al-Si-Mg alloys[J]. Mater. Des., 2013, 51: 767
[2] Chen R, Shi Y F, Xu Q Y, et al.Effect of cooling rate on the solidification parameters and microstructure of Al-7Si-0.3Mg-0.15Fe alloy[J]. Trans. Nonferrous Met. Soc. China, 2014, 24: 1645
[3] Ceschini L, Morri A, Morri A, et al.Correlation between ultimate tensile strength and solidification microstructure for the sand cast A357 aluminium alloy[J]. Mater. Des., 2009, 304: 4525
[4] Samuel A M, Samuel F H.A metallographic study of porosity and fracture behavior in relation to the tensile properties in 319.2 end chill castings[J]. Metall. Mater. Trans., 1995, 26A: 2359
[5] Shivkumar S, Ricci S, Keller C, et al.Effect of solution treatment parameters on tensile properties of cast aluminum alloys[J]. J. Heat. Treating, 1990, 8: 63
[6] Myhr O R, Grong ?.Modelling of non-isothermal transformations in alloys containing a particle distribution[J]. Acta Mater., 2000, 48: 1605
[7] Myhr O R, Grong ?, Andersen S J.Modelling of the age hardening behaviour of Al-Mg-Si alloys[J]. Acta Mater., 2001, 49: 65
[8] Bahrami A, Miroux A, Sietsma J.An age-hardening model for Al-Mg-Si alloys considering needle-shaped precipitates[J]. Metall. Mater. Trans., 2012, 43A: 4445
[9] Hollomon J H.Tensile deformation[J]. Trans. Metall. Soc. AIME, 1945, 162: 269
[10] Ludwigson D C.Modified stress-strain relation for FCC metals and alloys[J]. Mech. Transact., 1971, 2: 2825
[11] Voce E.The relationship between stress and strain for homogeneous deformation[J]. J. Inst. Met., 1948, 74: 537
[12] Cheng L M, Poole W J, Embury J D, et al.The influence of precipitation on the work-hardening behavior of the aluminum alloys AA6111 and AA7030[J]. Metall. Mater. Trans., 2003, 34A: 2473
[13] Myth O R, Grong ?, Pedersen K O.A combined precipitation, yield strength, and work hardening model for Al-Mg-Si alloys[J]. Metall. Mater. Trans., 2010, 41A: 2276
[14] Bahrami A, Miroux A, Sietsma J.Modeling of strain hardening in the aluminum alloy AA6061[J]. Metall. Mater. Trans., 2013, 44A: 2409
[15] Zhao Q L, Holmedal B.Modelling work hardening of aluminium alloys containing dispersoids[J]. Philos. Mag., 2013, 93: 3142
[16] Fribourg G, Bréchet Y, Deschamps A, et al.Micorstructure-based modelling of isotropic and kinematic strain hardening in a precipitation-hardened aluminum alloy[J]. Acta Mater., 2011, 59: 3621
[17] Bardel D, Perez M, Nelias D, et al.Cyclic behaviour of a 6061 aluminium alloy: Coupling precipitation and elastoplastic modeling[J]. Acta Mater., 2015, 83: 256
[18] Drouzy M, Jacob S, Richard M.Interpretation of tensile results by means of quality index and probable yield strength[J]. Int. J. Cast Met. Res., 1980, 5: 43
[19] Tiryakio?lu M, Staley J T, Campbell J.Evaluating structural integrity of cast Al-7Si-Mg alloys via work hardening characteristics II. A new quality index[J]. Mater. Sci. Eng., 2004, A368: 231
[20] Mondal C, Singh A K, Mukhopadhyay A K, et al.Tensile flow and work hardening behavior of hot cross-rolled AA701 aluminum alloy sheets[J]. Mater. Sci. Eng., 2013, A577: 87
[21] Chen R, Xu Q Y, Liu B C.Modelling investigation of precipitation kinetics and strengthening for needle/rod-shaped precipitates in Al-Mg-Si alloys[J]. Acta Metall. Sinc., 2016, 52: 987(陈瑞, 许庆彦, 柳百成. Al-Mg-Si合金中针棒状析出相时效析出动力学及强化模拟研究[J]. 金属学报, 2016, 52: 987)
[22] Du Q, Poole W J, Wells M A.A mathematical model coupled to CALPHAD to predict precipitation kinetics for multicomponent aluminum alloys[J]. Acta Mater., 2012, 60: 3830
[23] Chen Q, Jeppsson J, ?gren J.Analytical treatment of diffusion during precipitate growth in multicomponent systems[J]. Acta Mater., 2008, 56: 1890
[24] Bardel D, Perez M, Nelias D, et al.Coupled precipitation and yield strength modelling for non-isothermal treatments of a 6061 aluminium alloy[J]. Acta Mater., 2014, 62: 129
[25] Ardell A J.Precipitation hardening[J]. Metall. Trans., 1985, 16A: 2131
[26] Zhao Q L, Holmedal B.Modelling work hardening of aluminium alloys containing dispersoids[J]. Philos. Mag., 2013, 93: 3142
[27] Callister W D, David G R.Fundamentals of Materials Science and Engineering: An integrated approach[M]. 4th Ed., New York: John Wiley & Sons Inc, 2012: 1
[28] Proudhon H, Poole W J, Wang X, et al.The role of internal stresses on the plastic deformation of the Al-Mg-Si-Cu alloy AA6111[J]. Philos. Mag., 2008, 88: 621
[29] Simar A, Bréchet Y, de Meester B, et al. Sequential modeling of local precipitation, strength and strain hardening in friction stir welds of an aluminum alloy 6005A-T6[J]. Acta Mater., 2007, 55: 6133
[30] Sinclair C W, Poole W J, Bréchet Y.A model for the grain size dependent work hardening of copper[J]. Scr. Mater., 2006, 55: 739
[31] Zolotorevsky N Y, Solonin A N, Churyumov A Yu, et al.Study of work hardening of quenched and naturally aged Al-Mg and Al-Cu alloys[J]. Mater. Sci. Eng., 2009, A502: 111
[32] Chen R, Xu Q Y, Wu Q F, et al.Nucleation model and dendrite growth simulation in solidification process of Al-7Si-Mg alloy[J]. Acta Metall. Sinc., 2015, 51: 733(陈瑞, 许庆彦, 吴勤芳等. Al-7Si-Mg合金凝固过程形核模型建立及枝晶生长过程数值模拟[J]. 金属学报, 2015, 51: 733)
[33] Liu F, Yu F X, Zhao D Z, et al.Transmission electron microscopy study of precipitates in an artificially aged Al-12.7Si-0.7Mg alloy[J]. Mater. Charact., 2015, 107: 211
[34] 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
[35] Chomsaeng N, Haruta M, Chairuangsri T, et al.HRTEM and ADF-STEM of precipitates at peak-ageing in cast A356 aluminium alloy[J]. J. Alloys Compd., 2010, 496: 478
[36] Son S K, Matsumura S, Fukui K, et al.The compositions of metastable phase precipitates observed at peak hardness condition in an Al-Mg-Si alloy[J]. J. Alloys Compd., 2011, 509: 241
[37] Wang X, Embury J D, Poole W J, et al.Precipitation strengthening of the aluminum alloy AA6111[J]. Metall. Mater. Trans., 2003, 34A: 2913
[38] Sj?lander E, Seifeddine S, Svensson I L.Modelling yield strength of heat treated Al-Si-Mg casting alloys[J]. Int. J. Cast Metal. Res., 2011, 24: 338
[39] Brown L M, Stobbs W M.The work-hardening of cooper-silica[J]. Philos. Mag., 1971, 23: 1185
[40] Andersen S J, Marioara C D, Fr?seth A, et al.Crystal structure of the orthorhombic U2-Al4Mg4Si4 precipitate in the Al-Mg-Si alloy system and its relation to the β' and β" phases[J]. Mater. Sci. Eng., 2005, A390: 127
[41] Ceschini L, Morri A, Toschi S, et al.Microstructural and mechanical properties characterization of heat treated and overaged cast A354 alloy with various SDAS at room and elevated temperature[J]. Mater. Sci. Eng., 2015, A648: 340
[42] Haghdadi N, Zarei-Hanzaki A, Roostaei Ali A, et al.Evaluating the mechanical properties of a thermomechanically processed unmodified A356 Al alloy employing shear punch testing method[J]. Mater. Des., 2013, 43: 419
[43] Maisonnette D, Suery M, Nelias D, et al.Effects of heat treatments on the microstructure and mechanical properties of a 6061 aluminium alloy[J]. Mater. Sci. Eng., 2011, A528: 2718
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