锻压技术

应变速率对7050铝合金性能的影响及强化机理

英文标题：Influence of strain rate on properties for 7050 aluminum alloy and strengthening mechanism

作者：张鹏1 陈诚2 袁武华2

分类号：TG146.2

出版年,卷(期):页码：2021,46(10):225-232

摘要：

通过压机进行双道次压缩工艺，结合热处理，利用室温拉伸测试和微观组织表征方法，研究了应变速率对7050铝合金力学性能的影响，并在微观组织定量分析的基础上，研究了不同应变速率压缩时合金的强化机理。第1/2道次的应变速率由0.003 s-1/0.006 s-1增至0.1 s-1/0.2 s-1，平均晶粒尺寸由52 μm减小至36 μm，小角度晶界分数由47%降至37%，位错密度由2.50×1014 m-2降至1.68×1014 m-2，大角度晶界强化对屈服强度贡献值均为11 MPa，小角度晶界强化对屈服强度贡献值分别为5和4 MPa，位错强化对屈服强度贡献值由88 MPa降至69 MPa。结果表明：合金固溶时效后的强度随着应变速率的增加而减小；应变速率引起的合金强度变化主要由位错强化主导，大、小角度晶界对合金的强度变化影响不明显，且随着应变速率的增大，位错、大角度晶界、小角度晶界对合金屈服强度的贡献值之和减小，从而导致合金强度降低。

Through the double-pass compression process of press, combined with the heat treatment, the influences of strain rate on the mechanical properties of 7050 aluminum alloy were studied by room temperature tensile test and microstructure characterization method, and based on the quantitative analysis of microstructure, the strengthening mechanism of alloy during the compression at different strain rates was investigated. As the strain rates of the first/second pass increased from 0.003 s-1/0.006 s-1 to 0.1 s-1/0.2 s-1, the average grain size decreased from 52 μm to 36 μm, the small-angle grain boundary fraction decreased from 47% to 37%, the dislocation density reduced from 2.50×1014 m-2 to 1.68×1014 m-2, the contribution value of the large-angle grain boundary strengthening to the yield strength was 11 MPa, the contribution values of the small-angle grain boundary strengthening to the yield strength was 5 MPa and 4 MPa, respectively, and the contribution value of the dislocation strengthening to the yield strength decreased from 88 MPa to 69 MPa. The results show that the strength of alloy after solution-aging treatment decreases with the increasing of the strain rate, the strength change of alloy caused by the strain rate is mainly dominated by the dislocation strengthening, and the large-angle and small-angle grain boundaries have no obvious influence on the strength of alloy. As the strain rate increases, the sum of the contribution values for dislocations, large-angle grain boundary and small-angle grain boundary to the yield strength of alloy decreases resulting in a decrease in the strength of alloy.

基金项目：

作者简介：张鹏（1977-），男，博士研究生，高级工程师 E-mail：ezwhzp@163.com 通信作者：袁武华（1973-），男，博士，教授，博士生导师 E-mail：yuan46302@163.com

参考文献：

[1]张星临，陈送义，周亮，等.成分对Al-Zn-Mg-Cu超强铝合金淬火敏感性及组织性能的影响[J]. 稀有金属，2019, 43(6): 561-570.

Zhang X L, Chen S Y, Zhou L, et al. Effect of composition on quenching sensitivity and microstructures-properties of super-strength Al-Zn-Mg-Cu aluminum alloys[J]. Chinese Journal of Rare Metals, 2019, 43(6): 561-570.

[2]Luo J,Li M Q, Ma D W. The deformation behavior and processing maps in the isothermal compression of 7A09 aluminum alloy[J]. Materials Science and Engineering: A, 2012, 532(3):548-557.

[3]Wu H, Wen S P, Huang H,et al. Hot deformation behavior and constitutive equation of a new type Al-Zn-Mg-Er-Zr alloy during isothermal compression[J]. Materials Science & Engineering A，2016, 651:415-424.

[4]Zhao J, Deng Y, Tang J, et al. Influence of strain rate on hot deformation behavior and recrystallization behavior under isothermal compression of Al-Zn-Mg-Cu alloy[J]. Journal of Alloys and Compounds, 2019, 809:151788.

[5]Mao W M, Zhao X B. Metal Recrystallization and Grain Growth [M]. Beijing: Metallurgical Industry Press,1994.

[6]Humphrys F J, Hatherly M. Recrystallization and Related Annealing Phenomena [M]. UK：Elsevier, 2004.

[7]Cubero-Sesin J M, Arita M, Watanabe M, et al. High strength and high electrical conductivity of UFG Al-2%Fe alloy achieved by high-pressure torsion and aging[J]. IOP Conference Series: Materials Science and Engineering,2014,63(1): 012117.

[8]李周兵,沈健,闫亮明,等. 应变速率对7055铝合金显微组织和力学性能的影响[J].稀有金属,2010,34(5):643-647.

Li Z B, Shen J, Yan L M, et al. Influence of hot process strain rate on microstructures and tensile properties of 7055 aluminum alloy[J]. Chinese Journal of Rare Metals, 2010, 34(5):643-647.

[9]GB/T 228—2016, 金属材料室温拉伸实验方法[S].

GB/T 228—2016, Metallic materials—Tensile testing at ambient temperature [S].

[10] Sun Y Q, Peng L J, Huang G J, et al. Effect of Mg on the stress relaxation resistance of Cu-Cr alloys[J]. Materials Science and Engineering A, 2021, 799: 140144.

[11] 陈军洲. AA7055 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.

Chen J Z. Aging Precipitation Behavior and Mechanical Properties of AA7055 Aluminum Alloy[D]. Harbin: Harbin Institute of Technology，2008.

[12] Gang S, Cerezo A. Early-stage precipitation in Al-Zn-Mg-Cu alloy (7050)[J]. Acta Mater, 2004, 52: 4503-4516.

[13] Lee S H, Jung J G, Baik S I, et al. Precipitation strengthening in naturally aged Al-Zn-Mg-Cu alloy[J]. Materials Science and Engineering A, 2020, 803: 140719.

[14] Dixit M, Mishra R S, Sankaran K K. Structure-property correlations in Al7050 and Al7055 high-strength aluminum alloys[J]. Materials Science and Engineering A,2008, 478(1-2): 163-172.

[15] Cabibbo M. Microstructure strengthening mechanisms in different equal channel angular pressed aluminium alloys[J]. Materials Science and Engineering A，2013, 560: 413-432.

[16] Taylor G I. The mechanism of plastic deformation of crystals-Part II：Comparison with observations[J]. Proceedings of The Royal Society A, 1934, 145(855): 388-404.

[17] 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 Materialia, 1999, 47(14): 3855-3868.

服务与反馈：

【文章下载】【加入收藏】