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Designing new low alloyed Mg-RE alloys with high strength and ductility via high-speed extrusion

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International Journal of Minerals,Metallurgy and Materials 2023年第1期30卷 82-91页

作者： Jinshu Xie Zhi Zhang Shujuan Liu Jinghuai Zhang Jun Wang Yuying He Liwei Lu Yunlei Jiao Ruizhi Wu Key Laboratory of Superlight Material and Surface Technology Ministry of EducationCollege of Materials Science and Chemical EngineeringHarbin Engineering UniversityHarbin 150001China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China Ningbo Branch Ordnance Science Institute of ChinaNingbo 315103China School of Materials Science and Engineering Hunan University of Science and TechnologyXiangtan 411201China

Two new low-alloyed Mg-2RE-0.8Mn-0.6Ca-0.5Zn(wt%,RE=Sm or Y)alloys are developed,which can be produced on an in-dustrial scale via relatively high-speed extrusion.These two alloys are not only comparable to commercial AZ31 alloy in extrudability,but also have superior mechanical properties,especially in terms of yield strength(YS).The excellent extrudability is related to less coarse second-phase particles and high initial melting point of the two as-cast alloys.The high strength-ductility mainly comes from the formation of fine grains,nano-spaced submicron/nano precipitates,and weak texture.Moreover,it is worth noting that the YS of the two alloys can maintain above 160 MPa at elevated temperature of 250°C,significantly higher than that of AZ31 alloy(YS:45 MPa).The Zn/Ca solute segregation at grain boundaries,the improved heat resistance of matrix due to addition of RE,and the high melting points of strengthening particles(Mn,MgZn_(2),and Mg-Zn-RE/Mg-Zn-RE-Ca)are mainly responsible for the excellent high-temperature strength.

关键词： magnesium alloys high-speed extrusion high strength high ductility solute segregation

high ductility and Toughness of a Micro-duplex Medium-Mn Steel in a Large Temperature Range from—196 ℃ to 200 ℃

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Journal of Iron and Steel Research(International) 2015年第12期22卷 1126-1130页

作者： Si-lian CHEN Jun HU Xiao-dan ZHANG Han DONG Wen-quan CAO Central Iron and Steel Research Institute School of Materials Science and Engineering Huazhong University of Science and Technology Danish-Chinese Centre for Nanometals Section for Materials Science and Advanced CharacterizationDepartment of Wind EnergyTechnical University of Denmark

A medium-Mn steel （0.2C5Mn） was processed by intercritical annealing at different temperatures （625 ℃ and 650 ℃ ）. An ultrafine-grained micro-duplex structure consisting of alternating austenite and ferrite laths was de- veloped by austenite reverse transformation （ART） during intercritical annealing after forging and hot rolling. Ultra- high ductility with a total elongation higher than 30% was achieved in the temperature range from -196 ℃ to 200 ℃, and high impact toughness no less than 200 J at -40 ℃ was obtained. Based on the analysis of microstructure and mechanical properties, it was found that the enhanced ductility was determined by the phase transformation effect of austenite （TRIP effect）, while the delayed ductile to brittle transition was controlled by austenite stability.

关键词： high strength high ductility intercritical annealing medium-Mn steel ultrafine grain size

Toward the development of Mg alloys with simultaneously improved strength and ductility by refining grain size via the deformation process

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International Journal of Minerals,Metallurgy and Materials 2021年第1期28卷 30-45页

作者： Zhi Zhang Jing-huai Zhang Jun Wang Ze-hua Li Jin-shu Xie Shu-juan Liu Kai Guan Rui-zhi Wu Key Laboratory of Superlight Material and Surface Technology Ministry of EducationCollege of Material Science and Chemical EngineeringHarbin Engineering UniversityHarbin 150001China Ningbo Branch Ordnance Science Institute of ChinaNingbo 315103China Department of Materials Physics and Chemistry Harbin Institute of TechnologyHarbin 150001China

Magnesium(Mg) alloys, as the lightest metal engineering materials, have broad application prospects.However, the strength and ductility of traditional Mg alloys are still relativity low and difficult to improve simultaneously.Refining grain size via the deformation process based on the grain boundary strengthening and the transition of deformation mechanisms is one of the feasible strategies to prepare Mg alloys with high strength and high ductility.In this review, the effects of grain size on the strength and ductility of Mg alloys are summarized, and fine-grained Mg alloys with high strength and high ductility developed by various severe plastic deformation technologies and improved traditional deformation technologies are introduced.Although some achievements have been made, the effects of grain size on various Mg alloys are rarely discussed systematically and some key mechanisms are unclear or lack direct microscopic evidence.This review can be used as a reference for further development of high-performance fine-grained Mg alloys.

关键词： magnesium alloys grain refinement high strength high ductility deformation process

Recent developments of the high strength and high ductility nanostructured materials

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Baosteel Technical Research 2010年第S1期4卷 93-页

作者： Jian LU,Aiying CHEN,Hongning KOU,Ying LI,Leyu WANG and Chunsheng WEN Department of Mechanical Engineering,The Hong Kong Polytechnic University,Hung Hom Kowloon,Hong Kong,China

This talk will summarize the recent work related to a kind of new nanomaterials produced by the SMAT (surface mechanical attrition treatment).The concept of surface nanocrystallization of materials will be presented.In terms of the grain refinement mechanism induced by plastic deformation,a novel surface mechanical attrition(SMA) technique was developed for synthesizing a nanostructured surface layer on metallic materials in order to upgrade the overall properties and performance.The grain refinement mechanism of the surface layer during the SMA treatment will be analyzed in terms of the nanostructure observations in several typical materials.Very high yield stress(5 times of the base material) on the surface layer of the material obtained by the SMAT has been observed.The effect of surface nanostructures on the mechanical behavior and on the failure mechanism of metallic material shows the possibility to develop a new strength gradient composite using co-rolling and nitriding.The role of residual stress induced during the treatment will be investigated and discussed.The developed materials are also porosity free materials which can be used as reference material for the local mechanical behavior investigation technique such as the nanoindentation.A general concept for obtaining high strength and high ductility nanostructured materials will be presented.The exceptional high strength and high ductility steels have developed.The simulation of the mechanisms for improving ductility of high strength nanostructured materials will be presented.The potential applications for the land transportation vehicles(car,bus,train) and wind energy have been investigated.Some examples of concept design for the integration of the advanced nanostructured steels will be presented.

关键词： nanostructured materials high strength high ductility surface mechanical attrition treatment(SMAT)

Microstructure and mechanical properties of friction-stir-welded high-Mg-alloyed Al-Mg alloy plates at different rotating rates

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Rare Metals 2021年第8期40卷 2167-2178页

作者： Ying-Li Li Wei-Jun Xia Hong-Ge Yan Ji-Hua Chen Tian Ding You-Ping Sun Xin-Yu Li School of Materials Science and Engineering Hunan UniversityChangsha410082China Hunan Provincial Key Laboratory of Spray Deposition Technology and Application Hunan UniversityChangsha410082China School of Mechanical and Transportation Engineering Guangxi University of Science and TechnologyLiuzhou545006China

Hot-rolled high-Mg-alloyed Al-Mg alloy(Al-9.2 Mg-0.8 Mn-0.2 Zr-0.15 Ti,labeled as 5 A12)plates were successfully friction stir welded at rotating rates ranging from 750 to 1500 r·min^(-1) at a constant welding speed of50 mm·min^(-1).The joints were characterized by optical microscopy(OM),electron backscatter diffraction(EBSD),transmission electron microscopy(TEM),scanning electron microscopy(SEM),electron-dispersive spectroscopy(EDS),and tensile testing.All the joints are volume defectfree and exhibit fine,equiaxed dynamic recrystallization(DRX)grains with high-angle grain boundaries(HAGBs)fractions of 88.6%-93.3%in the nugget zones(NZs).The DRX grain size and the second-phase particle size in the NZs have a parabolic relation with the rotating rate.Furthermore,among the joints tested,the joint prepared at1000 r·min^(-1),which has the highest ultimate tensile strength((478±3)MPa)and the largest elongation to rupture(22.5%±1.4%)—approximately 87.5%and145.2%those of the base metal,respectively,exhibits the smallest grain size of 2.93μm,as well as the smallest particle size in the NZs.These excellent mechanical properties can be ascribed to the combined effects of the fine DRX grains with high fraction of HAGBs and the fine second-phase particles with a uniform distribution.

关键词： Al-Mg alloy Friction stir welding Dynamic recrystallization high ductility

A Study of the Microstructure and Properties of Dual-Phase Steels Processed Using A Continuous Galvanizing Line Simulation: The Benefits of Optimized Hot and Cold Rolling and the Addition of Vanadium

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A Study of the Microstructure and Properties of Dual-Phase S...