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Effect of Friction Coefficient on Deep Drawing of 6A16 Aluminum Alloy for Automobile Body

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Journal of Wuhan University of Technology(Materials Science) 2020年第1期35卷 208-214页

作者：刘钊扬熊柏青 li xiwu YAN lizhen li Zhihui ZHANG Yongan liU Hongwei State Key Laboratory of Nonferrous Metals and Processes GRIMAT Engineering Institute Co.Ltd.Beijing 101407China GRINM Engineering Institute Co. LTD.Beijing 101407China General Research Institute for Nonferrous Metal Beijing 100088China

Based on the ABAQUS/Explicit finite element method,the forming force changing trend of deep drawing test for 6A16 aluminum alloy plate after pre-aging and storage at room temperature for one month was simulated under friction coefficient ranging from 0 to *** lubricants selected for the tests were mechanical oil,butter and dry film lubricant,and the friction coefficient of these lubricants were 0.05,0.10 and 0.15,*** evolution of 6 A16 aluminum alloy plate during drawing forming was investigated by OM,SEM and *** results showed that,with the increase of friction coefficient,the stress,strain and deformation degree in deformation zone increased,while the grain size in deformation zone ***,the hardness of the cup-typed component increased with the increase of friction ***-lubricated cups had the highest tensile strength and yield strength after paint-bake *** combination of simulation results and microstructure analysis of 6A16 aluminum alloy plate after drawing forming indicates that the appropriate lubricant is butter.

关键词： finite element method 6A16 aluminum alloys deep drawing test friction coefficient

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Comprehensive investigation on the structural,electronic and mechanical properties of T-Mg_(32)(Al,Zn)_(49)phases in Al-Mg-Zn alloys

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Journal of Materials Science & Technology 2024年第6期173卷 237-246页

作者： Boyu Xue Wei Xiao xiwu li Guanjun Gao Xiaowu li Yongan Zhang ligen Wang Baiqing Xiong State Key Laboratory of Nonferrous Metals and Processes China GRINM Group Co.Ltd.Beijing 100088China GRIMAT Engineering Institute Co. Ltd.Beijing 101407China General Research Institute for Nonferrous Metals Beijing 100088China Department of Materials Physics and Chemistry School of Materials Science and EngineeringKey Laboratory for Anisotropy and Texture of MaterialsMinistry of EducationNortheastern UniversityShenyang 110819China

In the development process of crossover aluminum alloys,T-Mg_(32)(Al,Zn)_(49)phases play a significant role in the precipitation strengthening ***,comprehensive understandings of the structural characteristics,interactions among alloying elements,mechanical property dependence on composition variation,effects of doping and defects *** still inadequate.A combination of density functional theory(DFT)calculations and special quasi-random structures(SQSs)was applied to investigate the formation energies,lattice parameters,electronic structures and mechanical properties of the disordered T-phases,as well as the effects of possible defects and alloying *** formation energy and lattice constant of the T-phase gradually vary from 0 to-0.12 eV/atom and from 1.460 to 1.405 nm,respectively,with increasing Zn ***-3d orbitals exhibit stronger hybridization with Al-3s than Mg-3s orbitals,and this is further enhanced by increasing Zn contents,leading to improved covalency and mechanical properties of the *** T-phases show good ductility according to the Poisson's ratio ν,Cauchy's pressure and G/*** A site is more favorable to remain vacant in Al-rich and Zn-poor environments,which is consistent with the previous experimental *** alloying elements,Zn atoms tends to occupy Al atoms at the B,C and F sites and Mg atoms at the G *** Cu and Ag elements can decrease the formation energy of T-phases and possibly produce a greater number of T-phases during the precipitation *** effect of Ag is more significant relative to Cu due to the deeper orbital *** computational results show good agreement with previous experimental data and provide new insights into the compositional design of new Al-Mg-Zn alloys.

关键词： Al-Mg-Zn alloys Precipitation Mechanical properties Thermodynamic stability Density functional theory

Experimental and DFT Investigations of AlNbTiVZr High Entropy Alloys with Excellent Mechanical Properties

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Acta Metallurgica Sinica(English Letters) 2024年第9期37卷 1480-1490页

作者： Hongwei Yan Yong'an Zhang Wei Xiao Boyu Xue Rui liu xiwu li Zhihui li Baiqing Xiong State Key Laboratory of Nonferrous Metals and Processes China GRINM Group Co.Ltd.Beijing100088China GRIMAT Engineering Institute Co. Ltd.Beijing101407China General Research Institute for Nonferrous Metals Beijing100088China

This study investigated the microstructure and mechanical properties of AlNbTiVZr series high-entropy alloys(HEAs)through both experimental studies and density functional theory *** improvements in the microstructures and mechanical properties were achieved for the AlNbTiVZr series HEAs by meticulously adjusting the alloy composition and employing homogenization heat ***,the specimen designated as Al_(0.5)NbTiVZr_(0.5) demonstrated excellent mechanical properties including a compressive yield strength of 1162 MPa and a compressive strength of 1783 *** homogenization heat treatment at 1000℃ for 24 h,the Al_(0.5)NbTiVZr_(0.5) alloy exhibits brittle-to-ductile *** atomic-scale theoretical simulations reveal that the decrease of Al content intrinsically enhances the ductility of the alloys,thereby indicating that the mechanical properties of the AlNbTiVZr series HEAs were significantly influenced by the chemical ***,specific atomic pair formations were observed to adversely affect the microstructure of the AlNbTiVZr series HEAs,particularly in terms of *** findings provide valuable insights for the design and optimization of light weight HEAs,emphasizing the synergistic adjustment of alloy composition and heat treatment processes to achieve a balance between the strength and ductility.

关键词： High-entropy alloy Microstructure Mechanical properties Density functional theory

Aging behavior and fatigue crack propagation of high Zn-containing Al-Zn-Mg-Cu alloys with zinc variation

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Progress in Natural Science:Materials International 2017年第2期27卷 217-227页

作者： Kai Wen Yunqiang Fan Guojun Wang Longbing Jin xiwu li Zhihui li Yongan Zhang Baiqing Xiong State Key Laboratory of Non-ferrous Metals and Processes General Research Institute for Nonferrous Metals Northeast light Alloy Co. Ltd.

In the present work, the influence of two-step aging treatments on hardness, electrical conductivity and mechanical properties of two high Zn-containing Al-Zn-Mg-Cu alloys with zinc content variation was investigated and the detailed T76 aging parameters were proposed. The microstructure of the precipitates were studied by transmission electron microscopy(TEM) and high-resolution transmission electron microscopy(HREM) and then quantitatively investigated with the aid of an image analysis. The fatigue performances were researched by the fatigue crack propagation(FCP) rate test and fracture morphology was observed with scanning electron microscopy(SEM). The results show that the matrix precipitate size distributions of both alloys had significant difference, so as to fatigue crack propagation rates and fracture appearance. The shear and bypass mechanisms of dislocation-precipitate interactions were employed to explain the difference. Among the shearable precipitates, the proportion of larger size precipitates for the higher zinc content alloy is bigger than that for the lower zinc content alloy. The coarse shearable precipitates hinder the propagation of the fatigue cracks, leading to inferior FCP rate. For both alloys, the shear mechanism possesses the dominant factor, finally causing a preponderance in the FCP resistance for the higher zinc content alloy than the lower one.

关键词： Al-Zn-Mg-Cu alloy Fatigue crack propagation Precipitate Aging treatment

Dynamic Recrystallization Behavior of 7056 Aluminum Alloys during Hot Deformation

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Journal of Wuhan University of Technology(Materials Science) 2022年第1期37卷 90-95页

作者： SHI Guohui ZHANG Yong'an li xiwu li Zhihui YAN lizhen YAN Hongwei liU Hongwei XIONG Baiqing State Key Laboratory of Nonferrous Metals and Processes GRIMAT Engineering Institute Co.Ltd.Beijing 101407China GRINM Group Co. Ltd.Beijing 100088China

To investigate the dynamic recrystallization behavior of 7xxx aluminum alloys,the isothermal compression tests were carried on the 7056 aluminum alloy in the temperatures range of 320-440℃and in the strain rates range of 0.001-1 s^(-1).In addition,the microstructure of samples were observed via electron back scanning diffraction *** to the results,true stress and true strain curves were established and an Arrhenius-type equation was established,showing the flow stress increases with the temperature decreasing and the strain rate *** critical strain(ε_(c))and the critical stress(σ_(c))of the onset of dynamic recrystallization were identified via the strain hardening rate and constructed relationship between deformation parameters as follows:ε_(c)=6.71×10^(-4)Z^(0.1373) and σ_(p)=1.202σ_(c)+*** DRX is incomplete in this alloy,whose volume fraction is only 20%even if the strain reaches *** this study,the flow stress behavior and DRX behavior of 7056 aluminum alloys are deeply understood,which gives benefit to control the hot working process.

关键词： Al-Zn-Mg-Cu alloys flow stress behavior dynamic recrystallization hot deformation

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Macro-micro dynamic behaviors and fracture modes of roll bonded 7A52/7A01/7B52 aluminum laminates in high velocity deformation

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Progress in Natural Science:Materials International 2018年第4期28卷 510-519页

作者： Guochuan Zhu Shuhui Huang xiwu li Zhihui li Youzhi Tong Yongan Zhang Baiqing Xiong State Key Laboratory of Nonferrous Metals and Processes General Research Institute for Nonferrous Metals Northeast light alloy limited liability Company Heilongjiang

Damage tolerance improvement in the lamination of aluminum alloy plates and composites has been reported in many studies. In the present study the macro-micro dynamic deformation behavior and related mechanisms of 7A52/7A01/7B52 laminated plates processed by hot roll bonding of 7A52, 7A01 and 7B52 plate at high strain rates and quasi-static compression has been investigated. The microstructure of the laminated plates was examined with backscatter diffraction(EBSD) techniques, scanning and transmission electron microscopies. The results showed that with increased strain rate, obvious strain rate hardening was observed in the single layer specimens. The peak flow stress of the multilayer samples was slightly higher than that of the 7A52 monolayer samples and much lower than that of the 7B52 monolayer samples at the same strain rate. Beyond the peak stress state, the strain hardening was replaced by thermal softening in the 7A52 layer, leading to low resistance of deformation and high tendency to facilitate deformation-induced adiabatic shear bands(ASBs) that consist of dynamic recrystallized grains. ASBs in laminated samples were deflected and bifurcated at the interface of 7A52 layer. In addition, bifurcated ASBs converged at the interface between the 7A52 and 7A01 layers. The high deformation resistance observed in the laminate under dynamic loading was a consequence of the high capacity for strain hardening in the 7A01 layer. This hardening effectively overcame the influences of thermal softening and dynamic recovery during dynamic loading. This study provides an understanding of the laminate’s microstructure evolution during dynamic deformation and its relevance to the fracture modes of a multilayer structure under dynamic loading.

关键词： Laminated plate Fracture mode Microstructure Aluminum alloy Mechanical properties

Pre-aging on early-age behavior and bake hardening response of an Al-0.90Mg-0.80Si-0.64Zn-0.23Cu alloy

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Progress in Natural Science:Materials International 2016年第4期26卷 398-403页

作者： lizhen Yan Zhihui li Yong-an Zhang Baiqing Xiong xiwu li Hongwei liu Shuhui Huang Hongwei Yan State Key Laboratory for Nonferrous Metals and Processes General Research Institute for Nonferrous Metals

Pre-aging on early-age behavior and bake hardening response of an Al-0.90Mg-0.80Si-0.64 Zn alloy was investigated by differential scanning calorimetry(DSC), high resolution transmission electron microscopy(HRTEM), 3-dimensional atom probe(3DAP), Erichsen test and tensile test. The results indicated that pre-aged alloy exhibited excellent formability and bake-hardening response, while bake hardening response was poor in samples with natural aging. Clustering behavior during natural aging was inhibited by pre-aging. Numerous GP zones formed in pre-aged samples. GP zones were the nuclei of β′′ precipitates or directly transformed β′′ phases during paint baking process. A large number of β′′ phases were observed in pre-aged samples after paint bake treatment. There was no sign to indicate that β′′phase precipitated in natural aged samples after bake hardening treatment.

关键词： Al-Mg-Si-Zn-Cu alloy Pre-aging Bake hardening response Atom probe tomography

Near-microscopic grain boundary facilitates fatigue crack propagation in a polycrystalline Al–Zn–Mg–Cu alloy

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Progress in Natural Science:Materials International 2023年第1期33卷 120-125页

作者： Kai Wen xiwu li Baiqing Xiong Haitao lin Qinghong Wen Yanan li Hongwei Yan lizhen Yan Yongan Zhang Zhihui li Hongwei liu State Key Laboratory of Nonferrous Metals and Processes China GRINM Group Co. LTD. GRIMAT Engineering Institute Co. LTD. General Research Institute for Nonferrous Metals Southwest Aluminum(Group) Co. Ltd.

In present study, grain characteristics with sizes within 10–30 μm were fabricated from a same Al–Zn–Mg–Cu alloy, FCP behaviors of the alloys with small grain(SG alloy), medium grain(MG alloy) and large grain(LG alloy)were investigated and related fatigue fracture morphology was analyzed. With the enhancement of stress intensity factor range(ΔK), the alloy with larger grains possessed faster FCP rate, which were successively arranged as SG alloy > MG alloy > LG alloy at initial stage while turned to LG alloy > MG alloy > SG alloy at final stage for the stable expanding region. Except for conventional characteristics of striations, tearing ridges, secondary cracks,second phases, voids and dimples, more prominent grain boundary features appeared on fracture surface, especially for MG and LG alloy. The calculation of cyclic plastic zone(CPZ) sizes proved that grain boundary participated and promoted FCP behavior when CPZ covered grain and grain boundary together.

关键词： Fatigue crack propagation Grain size Grain boundary Cyclic plastic zone Al–Zn–Mg–Cu alloy

Disclosing the formation mechanisms of Ag-containing Laves phases at the atomic scale in an Al-Cu-Mg-Ag alloy

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Journal of Materials Science & Technology 2024年第17期184卷 111-121页

作者： Qilong liu xiwu li Wei Xiao Zhihui li Kai Zhu Kai Wen lizhen Yan Yanan li Yongan Zhang Manling Sui Baiqing Xiong State Key Laboratory of Nonferrous Metals and Processes China GRINM Group Co.LTD.Beijing 100088China GRIMAT Engineering Institute Co. LTD.Beijing 101407China General Research Institute for Nonferrous Metals Beijing 100088China Beijing Key Laboratory of Microstructure and Properties of Solids Faculty of Materials and ManufacturingBeijing University of TechnologyBeijing 100124China

In addition to the three well-known Ag-related precipitates(Ω,X′and Z)in the Al-Cu-Mg-Ag alloys,Ag can also be involved in the formation of the as-cast second ***,the effect of Ag ad-dition in Al-Cu-Mg-Ag alloys has not been completely studied and even the structure of the as-cast Ag-containing phases is still *** employing the focused ion beam(FIB)combined with transmis-sion electron microscopy(TEM)techniques and density functional theory(DFT)calculations,the forma-tion mechanisms of the Ag-containing phases in the as-cast Al-Cu-Mg-Ag alloys have been *** Ag-containing phases are a series of hexagonal C14-type Laves phases with continuously varying Ag concentrations,described as(Al_(x)Cuy Ag_(1-x-y))_(2)***,the specific occupancy sites of the atoms in(Al_(x)Cuy Ag_(1-x-y))_(2)Mg were *** formation of the(Al_(x)Cuy Ag_(1-x-y))_(2)Mg can be attributed to the stronger Ag-induced aggregation of solute atoms in the initial stage and the establishment of strong Ag-X(X=Al,Mg and Ag)bonding in the Ag-containing ***,our experiments have revealed the solidification sequence of Al-Cu-Mg-Ag alloys,and pointed out that(Al_(x)Cuy Ag_(1-x-y))_(2)Mg is formed at a lower temperature(493.9°C)through the reaction L■Al_(2)CuMg+(Al_(x)Cuy Ag_(1-x-y))_(2)*** study could have positive implications for refinement of the Al-Cu-Mg-Ag quaternary phase diagram and promote the composition-property design of novel aluminum alloys based on(Al_(x)Cuy Ag_(1-x-y))_(2)Mg in the future.

关键词： Al-Cu-Mg-Ag alloys Laves phases HAADF-STEM First-principles calculation Formation mechanisms