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Dynamic tensile behavior of az31b magnesium alloy at ultra-high strain rates

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Chinese Journal of Aeronautics 2015年第2期28卷 593-599页

作者： Geng Changjian Wu baolin Liu Fang Tong Wenwei Han Zhenyu Aviation Industry Corporation of China Engine Design and Research Institute School of Materials Science and Engineering Shenyang Aerospace University

The samples having {0001 } parallel to extruding direction （ED） present a typical true stress-true strain curve with concave-down shape under tension at low strain rate. Ultra-rapid ten- sile tests were conducted at room temperature on a textured az31b magnesium alloy. The dynamic tensile behavior was investigated. The results show that at ultra-high strain rates of 1.93 × 10^2 s^-1 and 1.70 × 10^3 s^-1, the alloy behaves with a linear stress-strain response in most strain range and exhibits a brittle fracture. In this case, {10-12} 〈 10-11 〉 extension twinning is basic deformation mode. The brittleness is due to the macroscopic viscosity at ultra-high strain rate, for which the external critical shear stress rapidly gets high to result in a cleavage fracture before large amounts of dislocations are activated. because { 10-12} tension twinning, { 10-11 } compressive twinning, basal 〈 a 〉 slip, prismatic 〈 a 〉 slip and pyramidal 〈 c ＋ a 〉 slip have different critical shear stresses （CRSS）, their contributions to the degree of deformation are very differential. In addition, Schmid factor plays an important role in the activity of various deformation modes and it is the key factor for the samples with different strain rates exhibit various mechanical behavior under dynamic tensile loading.

关键词： az31b magnesium alloy Schmid factor Slip Texture Twinning

As-extruded az31b magnesium alloy Fatigue Crack Propagation behavior

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Journal of Wuhan University of Technology(Materials Science) 2011年第6期26卷 1114-1120页

作者：张红霞王文先 College of Material Science and Engineering Taiyuan University of Technology

The fatigue crack propagation rate of as-extruded az31b magnesium alloy was studied. Compact tension [C（T）] of the notch direction parallel （T-L）, vertical （L-T）, and inclined at 45o to the extrusion direction was investigated. The experimental results indicate that the crack propagation direction is parallel to the extrusion direction for T-L and L-T specimens, whereas the specimen inclined at 45o has an angular deflection of 9° to 11° toward the extrusion direction. The T-L specimen has the fastest fatigue crack propagation rate, and the L-T specimen has the slowest rate, the fatigue crack propagation rate of the specimen inclined at 45o is between the two directions. The crack tip propagates by both transgranular and intergranular fractures. Fatigue fractures consist of cleavage plane or quasi-cleavage and are brittle fractures. The fatigue striation occurs for specimens inclined at 45o and its size is 3-15 μm.

关键词： az31b magnesium alloy fatigue crack propagation rate brittle fracture

Microstructure and mechanical properties of friction stir welding of az31b magnesium alloy added with cerium

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Journal of Rare Earths 2010年第2期28卷 316-320页

作者：于思荣陈显君黄志求刘耀辉 Key Laboratory of Automobile Materials (Jilin University) Ministry of Educationand College of Materials Science and EngineeringJilin University College of Materials Science and Engineering Jiamusi University

The az31b magnesium alloy sheet added with 0.5 wt.% Ce was welded with friction stir welding(FSW).The microstructures and mechanical properties of the welded joint were investigated.The results showed that the microstructures in the weld nugget zone were uniform and with small equiaxed grains.The grains in the heat-affected zone and the thermo-mechanical affected zone were coarser than those in the base metal zone and the weld nugget zone.The ultimate tensile strength of az31b magnesium alloy added with 0.5...

关键词： az31b magnesium alloy friction stir welding microstructure mechanical property rare earths

Laser Cladding Al-Si/Al_2O_3-TiO_2 Composite Coatings on az31b magnesium alloy

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Journal of Wuhan University of Technology(Materials Science) 2012年第6期27卷 1042-1047页

作者：崔泽琴 YANG Hongwei 王文先 WU Hongliang XU bingshe College of Materials Science and Engineering Taiyuan University of Technology Key Laboratory of Interface Science and Engineering in Advanced Materials(Taiyuan University of Technology) Ministry of Education

To improve the wear resistance and corrosion resistance of magnesium alloys, a 5 kW continuous wave CO2 laser was used to investigate the laser surface cladding on az31 b magnesium alloys with Al-Si/Al2O3-TiO2 composite powders. A detailed microstructure, chemical composition, and phase analysis of the composite coatings were studied by scanning electron microscopy （SEM）, energy dispersive spectroscopy （EDS）, and X-ray diffraction （XRD）. The laser cladding shows good metallurgical bonding with the substrate. The composite coatings are composed of Mgl7Al12, Al3Mg2, Mg2Si, Al2O3, and TiO2 phases. Compared to the average microhardness （50HV0.05） of the az3 1 b substrate, that of the composite coatings （230HV0.05） is improved significantly. The wear resistances of the surface layers were evaluated in detail. The results demonstrate that the wear resistances of the laser surface-modified samples are considerably improved compared to the substrate. It also show that the composite coatings exhibit better corrosion resistance than that of the substrate in 3.5wt% NaCI solution.

关键词： az31b magnesium alloy laser cladding Al-Si/Al2O3-TiO2 composite coating wear resistance corrosion resistance

Effects of cold and warm cross-rolling on microstructure and texture evolution of az31b magnesium alloy sheet

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Journal of magnesium and alloys 2018年第2期6卷 121-133页

作者： Litzy Lina Choquechambi Catorceno Hamilton Ferreira Gomes de Abreu Angelo Fernando Padilha Department of Metallurgical and Materials Engineering Federal University of Ceará-UFCCampus do Pici-Bloco 729CEP 60440-554 FortalezaCEBrazil Department of Metallurgical and Materials Engineering Polytechnic SchoolUniversity of São Paulo-USPAv.Professor Mello de Moraes2463CEP 05508-030 São PauloSPBrazil

Mg alloys conventionally rolled often present strong basal textures that affect negatively further deformations,limiting their applications.The present research found that cross-rolling experiences in adequate conditions can weaken those intense basal textures as a result of the interaction of deformation mechanisms and dynamic recrystallization.The effects of rolling temperature and strain rate on the microstructure and texture of an az31b magnesium alloy sheet generated heterogeneous microstructure where the initial basal texture was strengthened during cold cross-rolling and it was gradually weakening by the rolling reduction and the rolling temperature increases in such a way that a rather weak basal fiber was produced applying reductions higher than 15%at temperatures higher than 200℃.Their ODF functions supported the texture weakening,exhibiting a combination of two crystallographic orientations represented by{0001}and{0001}.

关键词： az31b magnesium alloy Microstructure Texture Cross rolling.

Microscopic Structure and Property of Double-Electrode Gas Metal Arc Welding of az31b magnesium alloy

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Journal of Shanghai Jiaotong university(Science) 2017年第3期22卷 286-290页

作者：马国红沈旭平奇文聂军叶佳 School of Mechanical Engineering Nanchang University Electronic Lens Center University of Kentucky

This paper focuses on the research on double-electrode gas metal arc welding(DE-GMAW) of az31 b magnesium alloy sheet with 2 mm thickness. During the welding process, stable hybrid arc of metal inert gas(MIG) and tungsten inert gas(TIG) is employed as welding heat source. Optical and electron microscopes are used to observe the microstructures of the weld joint. X-ray diffraction(XRD) and energy dispersive spectroscopy(EDS) are employed to identify the components in fusion zone. Microhardness is also tested. When the MIG current is 80 A, the perfect weld joint is obtained, though figures of fish scales are observed in all joints in the research. The fusion zone is formed by dendrites, where β-Mg17(Al, Zn)12is dispersed. The hardness in fusion zone and heat affected zone(Haz) is lower than that in base metal(bM). The average Vickers hardness of fusion zone and Haz is about 58 and 56 respectively, while the Vickers hardness of bM is about 63.

关键词： double-electrode gas metal arc welding(DE-GMAW) dendrite eutectic reaction az31b magnesium alloy

Mechanical strength and corrosion resistance of Al-additive friction stir welded az31b joints

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Journal of magnesium and alloys 2023年第5期11卷 1519-1535页

作者： Jae-Yeon Kim Eun-Woo Kim Dong-O Kim Eun-Kyo Ju Ji-Eun Lee Jaeheon Lee Jai-Won byeon Mining Engineering Department Colorado School of MinesGoldenCO 80401USA Department of Materials Science and Engineering Seoul National University of Science and TechnologySeoul 01811Republic of Korea

Compared to other structural alloys,magnesium alloys have a relatively poor corrosion resistance and low mechanical strength,which can be further deteriorated when these alloys are subjected to joining processes using the existing joining methods.Herein,we propose for the first time an additive friction stir-welding(AFSW)using fine Al powder as an additive to improve the mechanical strength as well as corrosion resistance of az31b weld joints.AFSW is a solid-state welding method of forming a high-Al az31b joint via an in-situ reaction between pure Al powders filled in a machined groove and the az31b matrix.To optimize the process parameters,AFSW was performed under different rotational and transverse speeds,and number of passes,using tools with a square or screw pin.In particular,to fabricate a weld zone,where the Al was homogenously dispersed,the effects of the groove shape were investigated using three types of grooves:surface one-line groove,surface-symmetric grooves,and inserted symmetric grooves.The homogenous and defect-less AFS-welded az31b joint was successfully fabricated with the following optimal parameters:1400 rpm,25 mm/min,four passes,inserted symmetric grooves,and the tool with a square pin.The AFSW fully dissolved the additive Al intoα-Mg and in-situ precipitated Mg_(17)Al_(12)particles,which was confirmed via scanning electron microscopy,transmission electron microscope,and X-ray diffraction analyses.The microhardness,joint efficiency,and elongation at the fracture point of the AFS-welded az31b joint were 80 HV,101%,and 8.9%,respectively.These values are higher than those obtained for the FS-welded az31 joint in previous studies.The corrosion resistance of the AFS-welded az31b joint,evaluated via hydrogen evolution measurements and potentiodynamic polarization tests,was enhanced to 55%relative to the FS-welded az31b joint.

关键词： az31b magnesium alloy Additive friction stir-welding In-situ reaction Mg_(17)Al_(12)particles Joint efficiency Corrosion resistance

The effect of extrusion conditions on the properties and textures of az31b alloy

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Journal of magnesium and alloys 2017年第2期5卷 202-209页

作者： Qiang Liu Xiao Zhou Haitao Zhou Xiaohui Fan Keming Liu Key Laboratory of Nonferrous Metal Materials Science and Engineering of Ministry of Education School of Materials Science and EngineeringCentral South UniversityChangsha 410083China Jiangxi Key Laboratory of Advanced Copper and Tungsten Materials Jiangxi Provincial Academy of ScienceNanchang 330029China

The effect of extrusion conditions on the tensile properties and texture of az31b alloy has been investigated by means of optical microscopy(OM),scanning electron microscopy(SEM),electron backscattered diffraction(EbSD)and tensile tests.It is found that the ultimate tensile strength(UTS),the yield strength(YS)and elongation(EN)of the extruded az31b alloy are more significantly influenced by extrusion velocities in contrast with temperature.Although the extrusion conditions are different,the {1102} texture is the chief texture in the az31b after extrusion.Moreover,the extrusion textures become scattered with increasing the temperatures at the same extrusion velocity.As the extrusion velocity is raised at the same temperature,the orientation density of textures increases and the separated textures become relatively concentrated.This leads to the changes of tensile properties at different extrusion conditions.©2017 Production and hosting by Elsevier b.V.on behalf of Chongqing University.

关键词： az31b magnesium alloy Hot extrusion Textures Properties Temperature

Microstructure and Mechanical Properties of Mg–3Al–Zn magnesium alloy Sheet by Hot Shear Spinning

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Acta Metallurgica Sinica(English Letters) 2020年第9期33卷 1226-1234页

作者： Fenghua Wang Peng Su Linxin Qin Shuai Dong Yunliang Li Jie Dong National Engineering Research Center of Light alloy Net Forming and State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong UniversityShanghai 200240China Sinopec Northwest Oilfield Company Urumqi 830011China School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200240China Shanghai Light alloy Net Forming National Engineering Research Center Co.Ltd Shanghai 201615China

Hot shear spinning experiments with Mg–3.0 Al–1.0 Zn–0.5 Mn(az31 b, wt%) magnesium alloy sheets were conducted at various temperatures, spindle speeds and feed ratios to investigate the effects of these processing parameters on the microstructure, crystallographic texture and mechanical properties. The az31 b sheet displayed good shear formability at temperatures from 473 to 673 K, spindle speeds from 300 to 600 rev/min and feed ratios from 0.1 to 0.5 mm/rev. During the dynamic recrystallization process, the grain size and texture were affected by the deformation temperature of the hot shear spinning process. Each of the spun sheets presented a strong basal texture, and the c-axis of most of the grains was parallel to the normal direction. The optimal hot shear spinning parameters were determined to be a temperature of 473 K, a spindle speed of 300 rev/min and a feed ratio of 0.1 mm/rev. The yield strength, ultimate tensile strength and elongation in the rolled direction reached 221 MPa, 288 MPa and 14.1%, and those in the transverse direction reached 205 MPa, 280 MPa and 12.4%, respectively. The improved strength and decreased mechanical anisotropy resulted from the fine grain size and strong basal texture.

关键词： az31b magnesium alloy Shear spinning Texture Grain refinement