Flow Behavior and Microstructure of 7A85 Aluminum Alloy During Hot Compression
QIU Li-li1, GAO Wen-li1, LU Zheng2, FENG Zhao-hui2
1. College of Materials Science and Engineering, Hunan University, Changsha 410082, China;
2. Beijing Institute of Aeronautical Materials, Beijing 100095, China
Abstract：The flow stress behavior and the microstructure evolution of as-cast 7A85 aluminum alloy were studied by the hot compression test, which was performed on Gleeble-3500 thermal simulation machine at 300-450℃ and strain rate 0.01-10s-1. The results show that the true stress is rising to peak stress rapidly in the initial deformation period, then the flow stress decreases due to dynamic recovery and dynamic recrystallization, finally the flow stress tends to be stable. The peak flow stress increases with decreasing deformation temperature and increasing strain rate. It can be described by Zener-Hollomon parameter. The constitutive equation of 7A85 aluminum alloy is obtained by linear regression, and the hot deformation activation energy Q is 253.68kJ/mol. With the decreasing of lnZ, the grains are elongated radially, the sub-grains grow up, the dislocation density and the quantity of second phase particles decrease. The softening mechanism is mainly dynamic recrystallization.
STARINK M J, WANG S C. A model for the yield strength of overaged Al-Zn-Mg-Cu alloys[J]. Acta Materialia, 2003, 51(17):5131-5150.
[2]
王少华,马志锋,张显峰,等. Al-Zn-Mg-Cu-Zr-0.5Er合金型材组织性能研究[J].材料工程, 2014,(3):27-33. WANG Shao-hua, MA Zhi-feng, ZHANG Xian-feng, et al. Investigation on microstructure and properties of Al-Zn-Mg-Cu-Zr-0.5Er alloy profile[J]. Journal of Materials Engineering, 2014,(3):27-33.
[3]
SHUEY R T, BARLAT F, KARABIN M E, et al. Experimental and analytical investigations on plane strain toughness for 7085 aluminum alloy[J]. Metallurgical and Materials Transactions A, 2009, 40(2):365-376.
[4]
LI X M, STARINK M J. Identification and analysis of intermetallic phases in overaged Zr-containing and Cr-containing Al-Zn-Mg-Cu alloys[J]. Journal of Alloys and Compounds, 2011, 509(2):471-476.
[5]
TALEGHANI J, RUIZ NAVAS E M, SALEHI M, et al. Hot deformation behaviour and flow stress prediction of 7075 aluminum alloy powder compacts during compression at elevated temperatures[J]. Materials Science and Engineering:A, 2012, 534:624-631.
[6]
ZHANG H, JIN N P, CHEN J H. Hot deformation behavior of Al-Zn-Mg-Cu-Zr aluminum alloys during compression at elevated temperature[J]. Transactions of Nonferrous Metals Society of China, 2011, 21(3):437-442.
[7]
陈学海,陈康华,梁信,等. 7085铝合金热变形的流变应力行为和显微组织[J].粉末冶金材料科学与工程, 2011, 16(2):225-230. CHEN Xue-hai, CHEN Kang-hua, LIANG Xin, et al. Flow stress behavior and microstructure of 7085 aluminum alloy during hot deformation[J]. Materials Science and Engineering of Powder Metallurgy, 2011, 16(2):225-230.
[8]
陈学海,陈康华,董朋轩,等. 7085铝合金的热变形组织演变及动态再结晶模型[J].中国有色金属学报, 2013, 23(1):44-50. CHEN Xue-hai, CHEN Kang-hua, DONG Peng-xuan, et al. Microstructure evolution and dynamic recrystallization model of 7085 aluminum alloy during hot deformation[J]. The Chinese Journal of Nonferrous Metals, 2013,23(1):44-50.
[9]
CHEN S Y, CHEN K H, PENG G S, et al. Effect of heat treatment on hot deformation behavior and microstructure evolution of 7085 aluminum alloy[J]. Journal of Alloys and Compounds, 2012, 537:338-345.
[10]
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.
[11]
贾逢博,易幼平,黄施全,等. 7A85铝合金热压缩流变行为与本构方程研究[J].热加工工艺, 2010,39(16):19-21. JIA Feng-bo, YI You-ping, HUANG Shi-quan, et al. Study on flow behavior and constitutive equation of 7A85 aluminum alloy during hot compression[J]. Hot Working Technology, 2010,39(16):19-21.
[12]
ROKNI M R, ZAREI-HANZAKI A, ROOSTAEI A A, et al. An investigation into the hot deformation characteristics of 7075 aluminum alloy[J]. Materials & Design, 2011, 32(4):2339-2344.
SHEPPARD T, JACKSON A. Constitutive equations for use in prediction of flow stress during extrusion of aluminum alloys[J]. Materials Science and Technology, 1997, 13(3):203-209.
[15]
陶乐晓,臧金鑫,张坤,等.新型高强Al-Zn-Mg-Cu合金的热变形行为和热加工图[J].材料工程, 2013, (1):16-20. TAO Le-xiao, ZANG Jin-xin, ZHANG Kun, et al. Hot deformation behavior and processing map for new Al-Zn-Mg-Cu alloy[J]. Journal of Materials Engineering,2013,(1):16-20.
[16]
HU H E, ZHEN L, YANG L, et al. Deformation behavior and microstructure evolution of 7050 aluminum alloy during high temperature deformation[J]. Materials Science and Engineering:A, 2008, 488(1):64-71.
[17]
WUSATOWSKA-SARNEK A M, MIURA H, SAKAI T. Nucleation and microtexture development under dynamic recrystallization of copper[J]. Materials Science and Engineering:A, 2002, 323(1):177-186.
2016, Vol. 44 
