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Journal of magnesium and alloys 2024年第1期12卷 98-109页

作者： Shi Shengnan Wang Hongyu Teng Fei Jiang Lei Sun Juncai Sun Jie Zhang Shunhu Transportation Engineering College Dalian Maritime UniversityDalianLiaoning 106026China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyangLiaoning 110819China Shagang School of Iron and Steel Soochow UniversitySuzhouJiangsu 215021China

magnesium alloy is one of the lightest metal structural materials.The weight is further reduced through the hollow structure.However,the hollow structure is easily damaged during processing.In order to maintain the hollow structure and to transfer the stresses during the high temperature deformation,the sand mandrel is proposed.In this paper,the hollow az31 magnesium alloy three-channel joint is studied by hot extrusion forming.Sand as one of solid granule medium is used to fill the hollow magnesium alloy.The extrusion temperatures are 230℃ and 300℃,respectively.The process parameters(die angle,temperature,bottom thickness,sidewall thickness,edge-to-middle ratio in bottom,bottom shape)of the hollow magnesium alloy are analyzed based on the results of experiments and the finite element method.The results are shown that the formability of the hollow magnesium alloy will be much better when the ratio of sidewall thickness to the bottom thickness is 1:1.5.Also when edge-to-middle ratio in bottom is about 1:1.5,a better forming product can be received.The best bottom shape in these experiments will be convex based on the forming results.The grain will be refined obviously after the extrusion.Also the microstructures will be shown as streamlines.And these lines will be well agreement with the mold in the corner.

关键词： az31 magnesium alloy Three-channel joint Sand Experiments and the finite element Die angle

Microstructure evolution and corrosion resistance of az31 magnesium alloy tube by stagger spinning

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International Journal of Minerals,Metallurgy and Materials 2022年第7期29卷 1361-1372页

作者： Fanlin Zheng Hongsheng Chen Yuanqi Zhang Wenxian Wang Huihui Nie College of Mechanical and Vehicle Engineering Taiyuan University of TechnologyTaiyuan 030024China Shanxi Key Laboratory of Advanced magnesium-Based Materials Taiyuan 030024China College of Materials Science and Engineering Taiyuan University of TechnologyTaiyuan 030024China

This study fabricates an az31 magnesium alloy tube by spinning technology-power stagger forward spinning.The microstructure evolution of the tube is investigated by combining electron backscatter diffraction and transmission electron microscopy analysis,and the corrosion resistance is measured by an electrochemical corrosion test.Results show that the grains are obviously more uniform and finer along the wall thickness’s direction of the az31 alloy tube after the third spinning pass.The number of twins ascends first and then descends,while the varying trend of low-angle grain boundaries(LAGBs)is opposite to that of the twins as the spinning pass increases.With the increase of the total spinning deformation,the deformation texture initially increases and the c-axis of the{0001}crystal plane gradually rotates to the axial direction of the tube;the deformation texture then decreases and the orientation of grains becomes more random.The main mechanism of grain refinement is dynamic recrystallization by the twin-induced way and bowing out of the nucleation at grain boundaries during the first and second pass.However,the dominant mechanism of the refined grain is the high-temperature dynamic recovery in the third pass,and the microstructure mainly consists of substructured grains.After the spinning deformation,the corrosion resistance of the az31 alloy tube decreases due to the combined effect of twins and high density-dislocations.

关键词： az31 magnesium alloy power stagger forward spinning microstructure evolution corrosion resistance

Edge crack damage analysis of az31 magnesium alloy hot-rolled plate improved by vertical roll pre-rolling

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镁合金学报(英文) 2023年第6期11卷 2151-2164页

作者： Zhiquan Huang Chuanlu Qi Jinchao Zou Hongyu Lai Hao Guo Junpeng Wang School of Mechanical Engineering Taiyuan University of Science and TechnologyTaiyuan 030024China Nsk(China)Research&Development Co. Ltd.Kunshan 215332China

In the present study,through vertical roll pre-rolling of az31 magnesium alloy hot-rolled plate at room temperature,the effect of different vertical roll pre-rolling reduction on edge crack of the plate during flat rolling was systematically studied.The evolution of microstructure and texture in the edge and middle of the plate after vertical roll pre-rolling,heating and rolling was analyzed by using EBSD technology.The results show that during the vertical roll pre-rolling,{10–12}primary twins and{10–12}-{10–12}secondary twins dominated the edge deformation,while{10–12}primary twins dominated the middle deformation.With the increase of vertical roll pre-rolling reduction,the twin volume fraction of the edge and the middle increased,and the difference between them decreased gradually.After heating,the twin orientation caused by vertical roll pre-rolling was still maintained,and there was a significant difference in grain size between the edge and the middle.When the reduction rate of flat rolling was 30%,cracks have already appeared in the initial plate,while the vertical roll pre-rolled samples showed extremely high rolling performance.When the reduction rate of flat rolling was 50%,the 8PR sample still had no crack initiation.In addition,after flat rolling of 50%,the initial plate showed a strong basal texture,while the maximum pole density of the 8PR plate was small,and the texture distribution was very scattered,showing the characteristics of weak orientation.

关键词： az31 magnesium alloy Vertical roll pre-rolling Edge crack {10–12}Twins Texture

Research on deformation mechanism of az31 magnesium alloy sheet with non-basal texture during uniaxial tension at room temperature:A visco-plastic self-consistent analysis

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Journal of magnesium and alloys 2022年第7期10卷 1994-2008页

作者： Li Hu Huyuan Lv Laixin Shi Yu Chen Qiang Chen Tao Zhou Mingao Li Mingbo Yang College of Material Science and Engineering Chongqing University of TechnologyChongqing 400054China Southwest Technology and Engineering Research Institute Chongqing 400039China

The relationship between activities of involved deformation mechanisms and the evolution of microstructure and texture during uniaxial tension of az31 magnesium alloy with a rare non-basal texture has been thoroughly investigated in the present study by means of electron backscattered diffraction(EBSD) measurement and visco-plastic self-consistent(VPSC) modeling. These results show that except basal slip and prismatic slip, {10■2} extension twin(ET) also plays a significant role during plastic deformation. With the increasing tilted angle between loading direction and rolling direction(RD) of sheet, the activity of {10■2} ET possesses a decreasing tendency and its role in plastic deformation changes from the one mainly sustaining plastic strain to the one mainly accommodating local strain between individual grains. When {10■2} ET serves as a carrier of plastic strain, it mainly results in the formation of basal texture component(c-axis//ND, normal direction). By comparison, when the role of {10■2} ET is to accommodate local strain, it mainly brings about the formation of prismatic texture component(c-axis//TD, transverse direction). At large plastic deformation, the competition between basal slip and pyramidal slip is responsible for the concentration of tilted basal poles towards ND within all deformed samples. The larger difference is between the activities of basal slip and pyramidal slip, the smaller separation is between these two tilted basal poles. Besides,VPSC modeling overesttmates volume fractions of {10■2} ET in samples with angle of 0 to 30° between loading direction and RD of sheet because interactions between twin variants are not included in VPSC modeling procedure at the present form. In addition, as compatible deformation between individual grains cannot be considered in VPSC modeling, the predicted volume fractions of {10■2} ET in samples with angle of 45 to 90° between loading direction and RD of sheet are smaller than the correspondingly measured results.

关键词： az31 magnesium alloy Non-basal texture Plastic deformation VPSC

Effect of grain refinement induced by wire and arc additive manufacture (WAAM) on the corrosion behaviors of az31 magnesium alloy in NaCl solution

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Journal of magnesium and alloys 2023年第1期11卷 217-229页

作者： Jianwei LI Youmin QIU Junjie YANG Yinying SHENG Yanliang YI Xun ZENG Lianxi CHEN Fengliang YIN Jiangzhou SU Tiejun ZHANG Xin TONG Bin GUO School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001PR China Beijing Hangxing Machinery Manufacture Limited Corporation Beijing 100013PR China Institute of Advanced Wear&Corrosion Resistant and Functional Materials Jinan UniversityGuangzhou 510632PR China The Third Academy of CASIC Beijing 100074PR China MOE Key Lab of Disaster Forecast and Control in Engineering Jinan UniversityGuangzhou510632P.R.China Institute of Materials and Process Design Helmholtz-Zentrum HereonMax-Planck-Str.121502 GeesthachtGermany School of Materials Science and Hydrogen Energy Foshan UniversityFoshan 528000PR China

Additive manufacturing(AM)of Mg alloys has become a promising strategy for producing complex structures,but the corrosion performance of AM Mg components remains unexploited.In this study,wire and arc additive manufacturing(WAAM)was employed to produce single az31 layer.The results revealed that the WAAM az31 was characterized by significant grain refinement with non-textured crystallographic orientation,similar phase composition and stabilized corrosion performance comparing to the cast az31.These varied corrosion behaviors were principally ascribed to the size of grain,where cast az31 and WAAM az31 were featured by micro galvanic corrosion and intergranular corrosion,respectively.

关键词： az31 magnesium alloy Wire and arc additive manufacturing(WAAM) Grain refinement Microstructure Intergranular corrosion

Dependence of Microstructure Evolution and Mechanical Properties on Loading Direction for az31 magnesium alloy Sheet with Non-basal Texture During In-Plane Uniaxial Tension

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Acta Metallurgica Sinica(English Letters) 2022年第2期35卷 223-234页

作者： Li Hu Mingao Li Qiang Chen Tao Zhou Laixin Shi Mingbo Yang College of Material Science and Engineering Chongqing University of TechnologyChongqing 400054China Southwest Technology and Engineering Research Institute Chongqing 400039China

In-plane uniaxial tension of az31 magnesium alloy sheet with non-basal texture has been conducted in order to demonstrate the effects of loading direction on the microstructure evolution and mechanical properties at ambient temperature.Loading axes are chosen to be along five directions distributed between rolling direction(RD)and transverse direction(TD),allowing various activities in involved slip and twinning modes to take place.As for twinning modes,electron backscattered diffraction observations confirm that the contribution of{1011}compression twinning is minimal to the plastic deformation of all deformed samples.By comparison,{1012}extension twinning(ET)not only serves as an important carrier on sustaining and accommodating plastic strain but also contributes to the emergence of TD-component texture with the progression of plastic strain.In terms of slip modes,analysis on Schmid factor demonstrates that the increasing tilted angle between loading direction and RD of sheet is unfavorable to the activation of basalslip,whereas it contributes to the activation of prismaticslip.These observations consequently explain the increasing tendency of 0.2%proof yield stress.Moreover,the activations of basalslip and{1012}ET collectively contribute to the concentration of two tilted basal poles toward normal direction.With increasing angle between loading direction and RD,the activations of basalslip and{1012}ET are gradually weakened.This leads to a weakening tendency about concentration of two tilted basal poles,a generally increasing tendency about Lankford value(r-value)and a generally decreasing tendency about strain-hardening exponent(n-value).

关键词： az31 magnesium alloy Non-basal texture Plastic deformation Microstructure evolution

Synergistic strengthening mechanism of gradient structure az31 magnesium alloy plate in hard plate rolling

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Progress in Natural Science:Materials International 2023年第5期33卷 652-659页

作者： Wen Tao Niu Feng Li Jia Yang Zhang Chao Li Lu Sun School of Materials Science and Chemical Engineering Harbin University of Science and Technology Key Laboratory of Advanced Manufacturing and Intelligent Technology Ministry of Education Harbin University of Science and Technology Heilongjiang Provincial Key Laboratory of Light Metal Materials Modification & Green Forming Technology Harbin University of Science and Technology

Compared with homogeneous structural materials, gradient structural materials are easier to realize the strengthductility optimization. Research on the strengthening mechanism of different gradient structure materials is a meaningful way to broaden the application of gradient structure materials. In this paper, the az31 magnesium alloy plate was rolled by hard plate rolling. The gradient structure was controlled by changing the initial plate thickness. When the initial plate thickness was 4 mm, az31 magnesium alloy shows excellent strength and ductility, the tensile strength was 282.2 MPa, and the ductility was 28.4 %. The change of the initial plate thickness changes the stress state which forming a gradient structure with different characteristic layers. The extra strengthening between different characteristic layers improves the properties of gradient structure, which makes the magnesium alloy change from a uniaxial stress state to a multi-axial stress state during the tensile process. The increase of the characteristic layer induces more geometrically necessary dislocation accumulation, improving the gradient structure’s strength and ductility. This research provides a new design strategy for the forming and performance optimization of gradient structure magnesium alloy plate by hard plate rolling, which has good industrial production and application potential.

关键词： Hard plate rolling Gradient structure az31 magnesium alloy Extra strengthening Geometrically necessary dislocation

Roles of pH in the NH_(4)^(+)-induced corrosion of az31 magnesium alloy in chloride environment

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Journal of magnesium and alloys 2022年第11期10卷 3167-3178页

作者： Feng Ge Jiaxuan Yin Yue Liu Wenjun Leng Xin Wang Zhongyu Cui School of Materials Science and Engineering Ocean University of ChinaQingdao 266100China

Corrosion behavior of az31 magnesium alloy in NH_(4)^(+)-bearing chloride solution with controlled pH was investigated by weight loss experiment, hydrogen collection, and electrochemical test combined with surface morphology and topography observation. The results show that NH_(4)^(+) and pH of the solution can affect the corrosion of az31 magnesium alloy. The existence of NH4+affects the formation and dissolution of corrosion products, which makes the protective effect of the corrosion product layer weaker. The change of pH value not only affects the corrosion mechanism of az31, but also alters the concentration of NH_(4)^(+) ions in the solution, which further influences the corrosion product layer of az31, and finally makes the corrosion of az31 change significantly.

关键词： NH_(4)^(+) pH az31 magnesium alloy Corrosion

Review on the effect of different processing techniques on the microstructure and mechanical behaviour of az31 magnesium alloy

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Journal of magnesium and alloys 2021年第5期9卷 1709-1732页

作者： Rakshith M. Seenuvasaperumal P. School of Mechanical Engineering Vellore Institute of TechnologyVellore632014India

magnesium(Mg)alloys despite being the ideal candidate for structural applications,owing to their high specific strength and low density,are not widely used due to lack of active slip systems at room temperature in their hexagonal close-packed crystal structure,eliciting poor ductility and formability.Amongst the various series of Mg alloys,the az and ZK series alloys have been standouts,as they inherit better room temperature strength and flow characteristics through their solute elements.Grain refinement,as well as eliminating casting defects through metal processing techniques are vital for the commercial viability of these alloys since they play a key role in controlling the mechanical behaviour.As such,this review highlights the effect of different Bulk-deformation and Severe Plastic Deformation techniques on the crystal orientation and the corresponding mechanical behaviours of the az31 alloy.However,every process parameter surrounding these techniques must be well thought of,as they require specially designed tools.With the advent of finite element analysis,these processes could be computationally realized for different parameters and optimized in an economically viable manner.Hence,this article also covers the developments made in finite element methods towards these techniques.

关键词： az31 magnesium alloy Severe plastic deformation process Rolling Extrusion Finite element simulation

Effects of RE on Microstructures and Mechanical Properties of Hot-Extruded az31 magnesium alloy

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Journal of Rare Earths 2004年第4期22卷 527-532页

作者：刘英陈维平张卫文张大童李元元 Key Laboratory for Advanced Metallic Materials Processing and Forming of Guangdong South China University of Technology Guangzhou 510640 China

Effects of rare earth (RE) additions on microstructure and mechanical properties of the wrought az31 magnesium alloy were investigated. The results show that, by adding 0.3%, 0.6% and 1.0% RE elements, the as-cast microstructure can be refined, and the as-cast alloys′ elongation and tensile strength can be improved. After extrusion, the alloy with 0.3% and 0.6% RE additions obtain a finer microstructure and the best mechanical properties, but the alloy with 1.0% RE addition has the coarse Al-RE compound particles in grain boundaries which decreased elongation and tensile properties. Usually, Rare earth (RE) elements were used to improve the creep properties of aluminium-containing magnesium pressure die cast alloys at elevated temperatures. In this paper, it is also found that the high temperature strength of extruded materials can be increased by RE elements additions.

关键词： metal materials az31 magnesium alloy rare earth element microstructure mechanical properties