Optimizing microstructure and mechanical properties of heat-treated Al-Zn-Mg-Cu alloy by indirect hot deformation technology

Abstract

In this paper, the indirect thermal tensile experiments of 7075 aluminum alloy including the pre-deformation process at room temperature and the final heat tensile process were carried out, the plastic deformation behavior and forming limit of the material in the compound forming process were investigated considering three pre-deformation amounts 4%, 9%, 14%, two strain rates 0.001 s⁻¹, 0.01 s⁻¹ and four forming temperatures 300 °C, 350 °C, 400 °C, 450 °C. In the indirect hot forming process, the material is sensitive to the pre-deformation, strain rate, and forming temperature, when the strain rate is 0.01 s⁻¹, the pre-deformation amount is 4%, and the forming temperature is 400 °C, respectively, the maximum tensile deformation is 50 mm. Finally, taking the process in which the forming temperature is 450 °C as an example, according to the observation of the microstructure appearance of fracture, the fracture type in the hot forming process was judged as the ductile fracture. By analyzing the microstructure of the specimen treated with the quenching and artificial aging process, the eutectic T (AlZnMgCu) phase and α(Al) matrix formed a network of non-equilibrium alpha binary eutectic.

Keywords

strain rate / pre-deformation / forming temperature / AA7075 / compound tensile

References

[1] HirschJ, Al-SammanT. Superior light metals by texture engineering: Optimized aluminum and magnesium alloys for automotive applications [J]. Acta Materialia, 2013, 61(3): 818-843

[2] SheH, ShuD, DongA-P, et al.. Relationship of particle stimulated nucleation, recrystallization and mechanical properties responding to Fe and Si contents in hot-extruded 7055 aluminum alloys [J]. Journal of Materials Science & Technology, 2019, 35(11): 2570-2581

[3] YangY-B, ZhangZ-M, LiX-B, et al.. The effects of grain size on the hot deformation and processing map for 7075 aluminum alloy [J]. Materials & Design, 2013, 51: 592-597

[4] FanX-G, JiangD-M, MengQ-C, et al.. The microstructural evolution of an Al-Zn-Mg-Cu alloy during homogenization [J]. Materials Letters, 2006, 60(12): 1475-1479

[5] LiuX-Y, PanQ-L, FanX, et al.. Microstructural evolution of Al-Cu-Mg-Ag alloy during homogenization [J]. Journal of Alloys and Compounds, 2009, 484(1–2): 790-794

[6] CheginiM, ShaeriM H. Effect of equal channel angular pressing on the mechanical and tribological behavior of Al-Zn-Mg-Cu alloy [J]. Materials Characterization, 2018, 140: 147-161

[7] ZhangX-F, LuZ, GaoW-L, et al.. Heat treatment process of 7AXX aluminum alloy [J]. Heat Treatment of Metals, 2012, 37(2): 65-69

[8] ZaeffererS, KuoJ C, ZhaoZ, et al.. On the influence of the grain boundary misorientation on the plastic deformation of aluminum bicrystals [J]. Acta Materialia, 2003, 51(16): 4719-4735

[9] MerrimanC C, FieldD P, TrivediP. Orientation dependence of dislocation structure evolution during cold rolling of aluminum [J]. Materials Science and Engineering A, 2008, 494(1–2): 28-35

[10] XiaoG-F, JiangJ-F, LiuY-Z, et al.. Recrystallization and microstructure evolution of hot extruded 7075 aluminum alloy during semi-solid isothermal treatment [J]. Materials Characterization, 2019, 156: 109874

[11] RokniM R, Zarei-HanzakiA, AbediH R. Microstructure evolution and mechanical properties of back extruded 7075 aluminum alloy at elevated temperatures [J]. Materials Science and Engineering A, 2012, 532593-600

[12] AbedrabboN, PourboghratF, CarsleyJ. Forming of aluminum alloys at elevated temperatures-Part 1: Material characterization [J]. International Journal of Plasticity, 2006, 22(2): 314-341

[13] XiaoW-CStudy of unified viscoplastic constitutive modeling and key technologies of hot stamping of 7075 aluminum sheet [D], 2018, Beijing, University of Science and Technology Beijing(in Chinese)

[14] OmerK, AbolhasaniA, KimS, et al.. Process parameters for hot stamping of AA7075 and D-7xxx to achieve high performance aged products [J]. Journal of Materials Processing Technology, 2018, 257: 170-179

[15] BarianiP F, BruschiS, GhiottiA, et al.. Hot stamping of AA5083 aluminum alloy sheets [J]. CIRP Annals Manufacturing Technology, 2013, 62(1): 251-254

[16] XiaoW-C, WangB-Y, ZhengK-L. An experimental and numerical investigation on the formability of AA7075 sheet in hot stamping condition [J]. The International Journal of Advanced Manufacturing Technology, 2017, 92(9–12): 3299-3309

[17] RokniM R, Zarei-HanzakiA, RoostaeiA A, et al.. An investigation into the hot deformation characteristics of 7075 aluminum alloy [J]. Materials & Design, 2011, 32(4): 2339-2344

[18] MaK-K, WenH-M, HuT, et al.. Mechanical behavior and strengthening mechanisms in ultrafine grain precipitation-strengthened aluminum alloy [J]. Acta Materialia, 2014, 62: 141-155

[19] MaK-K, HuT, YangH, et al.. Coupling of dislocations and precipitates: Impact on the mechanical behavior of ultrafine grained Al-Zn-Mg alloys [J]. Acta Materialia, 2016, 103: 153-164

[20] WertJ A, PatonN E, HamiltonC H, et al.. Grain refinement in 7075 aluminum by thermomechanical processing [J]. Metallurgical Transactions A, 1981, 12(7): 1267-1276

[21] MohamedM S, FosterA D, LinJ-G, et al.. Investigation of deformation and failure features in hot stamping of AA6082: Experimentation and modelling [J]. International Journal of Machine Tools and Manufacture, 2012, 53(1): 27-38

[22] El-MagdE, AbouridouaneM. Characterization, modelling and simulation of deformation and fracture behaviour of the light-weight wrought alloys under high strain rate loading [J]. International Journal of Impact Engineering, 2006, 32(5): 741-758

[23] LiX CMicrostructure and metallographic atlasof aluminum alloy [M], 2010, Beijing, Metallurgical Industry Press(in Chinese)

[24] SongZ. Flow stress characteristics and constitutive equation at high temperature for 7050 aluminum alloy [J]. Journal of Wuhan University of Technology, 2006, 28: 113-116

[25] FuX, AiX, LiuZ, WanY. Study on shear angle model of aluminum alloy 7050-T7451 in high speed machining [J]. China Mechanical Engineering, 2007, 18: 220-224(in Chinese)

[26] HuH E, ZhenL, YangL, et al.. Deformation behavior and microstructure evolution of 7050 aluminum alloy during high temperature deformation [J]. Materials Science and Engineering A, 2008, 488(1–2): 64-71

[27] GaoY-H. Dynamic compression and tensile properties of Al alloys LC4 and LY12CZ at high strain rate [J]. Material Science and Technology, 1994, 2(2): 24-29

[28] PengK-P, ChenW-Z, QianK-W. Study on dynamic strain aging phenomenon of 3004 aluminum alloy [J]. Materials Science and Engineering A, 2006, 415(1–2): 53-58

[29] LeeW S, SueW C, LinC-F, et al.. The strain rate and temperature dependence of the dynamic impact properties of 7075 aluminum alloy [J]. Journal of Materials Processing Technology, 2000, 100(1–3): 116-122

[30] YangH T, LuZ, GuJ L. Study on the flow stress of 7A60 ultra high strength aluminum alloy [J]. Journal of Aeronautical Materials, 2005, 2: 12-15

[31] YangY, KeY-L, DongH-Y. Study on correlation between parameters of “single factor” constitutive model and temperature for 7050 aviation aluminum-alloy [J]. Journal of Aeronautical Materials, 2007, 27(4): 19-24(in Chinese)

[32] YANG Yong, KE Ying-lin, DONG Hui-yue. Constitutive model of aviation aluminum-alloy material in metal machining [J]. The Chinese Journal of Nonferrous Metals, 2005(6): 854–859. (in Chinese)

[33] PedersenK O, WestermannI, FuruT, et al.. Influence of microstructure on work-hardening and ductile fracture of aluminium alloys [J]. Materials & Design, 2015, 70: 31-44

[34] ThamY W, FuM W, HngH H, et al.. Bulk nanostructured processing of aluminum alloy [J]. Journal of Materials Processing Technology, 2007, 192–193: 575-581

[35] PagliaC S, JataK V, BuchheitR G. The influence of artificial aging on the microstructure, mechanical properties, corrosion, and environmental cracking susceptibility of a 7075 friction-stir-weld [J]. Materials and Corrosion, 2007, 58(10): 737-750