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Hot deformation behavior of Mg-7.22Gd-4.84Y-1.26Nd-0.58Zr magnesium alloy

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Rare Metals 2011年第1期30卷 87-93页

作者： ZHANG Kui MA Minglong li xinggang li Yongjun liANG lichao BING Mengfen State Key Lab of Non-ferrous Metals and Processes General Research Institute for Nonferrous Metals Beijing 100088 China CNGC Shenyang Dong Ji Industries Group Corporation Shenyang 110045 China

The behavior evolvement of Mg-7.22Gd-4.84Y-1.26Nd-0.58Zr（GWN751K） magnesium alloy during the hot deformation process was *** flow stress behavior of the magnesium alloy over the strain rate range of 0.002 to 2.000 s^-1 and in the temperature range of 623 to 773 K was studied on a Gleeble-1500D hot simulator under the maximum deformation degree of 60%.The experimental results showed that the relationship between stress and strain was obviously affected by strain rate and deformation *** flow stress of GWN751K magnesium alloy during high temperature deformation could be represented by the Zener-Hollomon parameter in the hyperbolic Arrhenius-type *** stress exponent n and deformation activation energy Q were evaluated by linear regression *** stress exponent n was fitted to be *** hot deformation activation energy of the alloy during hot deformation was 230.03 kJ/*** microstructures of hot deformation were also influenced by strain rate and compression temperature *** was found that the alloy could be extruded at 723 K with the mechanical properties of σ0.2 = 260 MPa,σb = 320 MPa,and δ = 18%.

关键词： magnesium alloys rare earth elements microstructure activation energy deformation hot working

Hot deformation behavior and finite element simulation of Mg-8.3Gd-4.4Y-1.5Zn-0.8Mn alloy

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Journal of Rare Earths 2022年第5期40卷 831-839,I0006页

作者： Jiabin Fan Minglong Ma Kui Zhang Yongjun li xinggang li Guoliang Shi Jiawei Yuan State Key Laboratory of Nonferrous Metals and Process GRINM Co.Ltd..Beijing 100088China GRIMAT Engineering Institute Co.Ltd Beijing 101407China General Research Institute for Nonferrous Metals Beijing 100088China

To study the hot deformation behavior of Mg-8.3 Gd-4.4 Y-1.5 Zn-0.8 Mn(wt%) alloy,hot compression tests were conducted using a Gleeble-3500 thermal simulator at temperatures ranging from 653 to773 K,true strain rates of 0.001-1 s^(-1),and a deformation degree of 60%.Results of hot compression experiments show that the flow stress of the alloy increases with the strain *** true stress-true strain curves are corrected by correcting the effect of temperature rise in the deformation *** energy,Q,equal to 287380 J/mol and material constant,n,equal to 4.59 were calculated by fitting the true stress-true strain ***,the constitutive equation was established and verified via finite element *** of the hot processing map show that the probability of material instability increases with the degree of deformation,which indicates that the material is not suitable for large deformation in a single *** the whole,the alloy is appropriate for multipass processing with small deformation and a suitable processing temperature and strain rate are 733 K and 0.01 s-1,respectively.

关键词： Mg-Gd-Y-Zn-Mn alloy Hot deformation Constitutive relationship Finite element simulation Processing map Rare earths

Microstructure evolution,mechanical properties and creep mechanisms of Mg-12Gd-1MM-0.6Zr(wt%)magnesium alloy

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Journal of Rare Earths 2021年第5期39卷 600-608页

作者： Bibo li Kui Zhang Guoliang Shi Kaikun Wang Yongjun li xinggang li Minglong Ma Jiawei Yuan State Key Laboratory of Nonferrous Metals and Process GRINM Group Co.Ltd.(GRINM)Beijing 100088China School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China GRIMAT Engineering Institute Co. Ltd.Beijing 101407China General Research Institute for Nonferrous Metals Beijing 100088China

In this research,the microstructure evolution,mechanical properties,and creep mechanisms of Mg-12 Gd-1 MM-0.6 Zr(wt%)alloy under different conditions were systematically studied using scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray diffraction(XRD),and tensile creep *** the microstructure of the as-cast sample,the average grain size is about 42μm,and the eutectic compounds were determined to be Mg_(5)(Gd_(0.8)MM_(0.2)).During homogenization,these eutectic compounds gradually dissolve,and Mg_(12)MM particles are *** hot extrusion,complete dynamic recrystallization(DRX)occurs,resulting in equiaxial grains with an average grain size of about 12μm and the formation of streamlines consisting of Mg_(12)MM particles along the extrusion direction(ED).After T5 treatment(225℃for 7 h),a large number ofβ'(Mg_(7)Gd)phases are precipitated on the{11-20}αhabit plane and are interconnected,forming an interlaced network *** ultimate tensile strength(R_(m)=405 MPa)and yield strength(R_(P0.2)=288 MPa)of the T5 sample are significantly higher than those of the as-extruded sample(R_(m)=289 MPa,R_(P0.2)=185 MPa),but the elongation(A=4%)was remarkably lower than that of the as-extruded sample(A=18%).When crept at225℃under 100 MPa,the steady-state creep rates of the as-cast,as-extruded,and T5 samples are1.59×10^(-8),1.08×10^(-8),and 1.40×10^(-8)s^(-1),respectively,and their total strains within 100 h are respectively breaking,0.81%,and 0.92%,indicating that the as-extruded alloy exhibits the best creep *** analysis reveals that,during the creep process of the T5 sample,theβ'particles coarsen and the precipitate-free zones(PFZs)widen,which increase the steady-state creep rate and the total strain within 100 h as compared with the as-extruded sample.

关键词： Magnesium alloy Extrusion Creep mechanism Microstructure evolution Precipitation Rare earths

Hot Deformation Behavior of AZ40 Magnesium Alloy at Elevated Temperatures

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Journal of Wuhan University of Technology(Materials Science) 2017年第6期32卷 1470-1475页

作者：赖林张奎 MA Minglong li xinggang li Yongjun SHI Guoliang YUAN Jiawei State Key Laboratory for Fabrication and Processing of Nonferrous Metals Beijing General Research Institute for Nonferrous Metals

Hot compression tests on AZ40 magnesium alloy were conducted on a Gleeble 1500 d hot simulation testing machine in a deformation temperature range of 330 ℃-420 ℃ and a strain rate range of 0.002-2 s^-1. Hot deformation behaviors were investigated on the basis of the analysis of the flow stressstrain curves, constitutive equation, and processing map. The stress exponent and apparent activation energy were calculated to be 5.821 and 173.96 k J/mol, respectively. Deformation twins and cracks located in grain boundaries were generated at 330 ℃ and 0.02 s^-1, which are associated with a high strain rate and a limited number of available slip systems. With increasing temperature and decreasing strain rate, the twins disappeared and the degree of dynamic recrystallization increased. The alloy was completely dynamically recrystallized at 420 ℃ and 0.002 s^-1, with a homogenous grain size of approximately 13.7 μm. The instability domains of the deformation behavior can be recognized by processing maps. By considering the processing maps and characterizing the microstructure, the optimum hot deformation parameters in this experiment were determined to be 420 ℃ and 0.002 s^-1.

关键词： AZ40 magnesium alloy hot compression processing map recrystallization

Phase constitutions,growth pattern and mechanical properties of Mg-1.4Gd-1.2Y-xZn-0.15Zr(at%) alloys

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Journal of Rare Earths 2020年第3期38卷 315-323页

作者： Dongjie Chen Yongjun li Kui Zhang xinggang li Minglong Ma Guoliang Shi Jiawei Yuan Ting li State Key Laboratory of Nonferrous Metals and Process GRINM Group Co.Ltd. Beijing 100088 China GRIMAT Engineering Institute Co. Ltd. Beijing 101407 China General Research Institute for Nonferrous Metals Beijing 100088 China National Center of Analysis and Testing for Nonferrous Metals and Electronic Materials GRINM Group Co.Ltd. Beijing 100088 China Guobiao(Beijing)Testing&Certification Co. Ltd. Beijing 100088 China

The effects of minor Zn(0.2 at%,0.4 at%,0.6 at%) on the microstructures and mechanical properties of Mg-1.4 Gd-1.2 Y-0.15 Zr(at%) alloys were systematically *** reveal that increasing Zn content leads to the increase of the intergranular phases and the change of their composition from Mg24(Gd,Y)5 phase and(Mg,Zn)3(Gd,Y) phase to 18 R-LPSO phase and(Mg,Zn)3(Gd,Y) ***24(Gd,Y)5 phase is body-centered cubic structure and shares the same lattice constant with Mg24Y5 while(Mg,Zn)3(Gd,Y)phase is face-centered cubic structure with lattice constant of 0.72 nm,slightly lower than Mg3Gd.18RLPSO structure is identified to be monoclinic with c-axis not strictly vertical to the bottom surface but93.5°.The growth patterns of intergranular phases change from the divorced growth to coupled growth as compositions ***,the mechanical performance improves with Zn rising,ascribed to the decrease of brittle phases at grain boundaries and the increase of LPSO structure phases.

关键词： Mg-Gd-Y-Zn alloy Long period stacking ordered(LPSO) Phase growth Mechanical properties Rare earths

Metallurgical characterization of Ti-bearing 9Cr low activation martensitic steel

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Acta Metallurgica Sinica(English Letters) 2011年第1期24卷 9-17页

作者： Rong MA Yafeng YANG Qingzhi YAN Ying YANG xinggang li Changchun GE Institute of Nuclear Materials University of Science and Technology Beijing Beijing 100083 China

Two heats of low activation martensitic （LAM） steels with Ti and Ta （denominated as 9Cr-Ti and 9Cr-Ta）, respectively, developed as candidate structure materials for nuclear reactor were characterized. This paper was focused on the effect of titanium on the microstructures and mechanical properties of 9Cr LAM steel in as-received condition （normalized at 950 ℃ for 30 min with water quenching plus tempered at 780 ℃ for 90 min with air cooling）. Chemical analysis and microstructure observation were conducted on 9Cr-Ti and 9Cr-Ta with optical microscopy, X-ray diffraction analysis, scanning electron microscopy and transmission electron microscopy. Impact properties and tensile strengths were measured with Charpy impact experiments and tensile tests. The results indicated that 9Cr-Ti and 9Cr-Ta were fully martensitic steels in as-received condition. MX type and M23C6 type precipitates were observed distributing along boundaries of prior austenite grains and martensite laths in *** addition of titanium accelerated the precipitation of TiC and TiN, and produced much finer grains in 9Cr-Ti than 9Cr-Ta at the same normalization temperature. Mechanical properties tests showed the ductile brittle transition temperatures of 9Cr- Ti and 9Cr-Ta were about -90℃ and -85℃, respectively. The ultimate tensile strengths at room temperature and 600℃,were 680 MPa and 365 MPa for 9Cr-Ti, and 660 MPa and 335 MPa for 9Cr-Ta, respectively. The favorite impact toughness and tensile properties of 9Cr-Ti could be attributed to the fine grains in as-received condition.

关键词： 9Cr low activation martensitic steel Alloying effect Microstructure Mechanical properties

复合型建筑城市一体化深化设计方法初探--以北京隆福寺东院为例

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建筑技艺（中英文） 2024年第6期30卷 50-59页

作者：侯新觉邱涧冰李兴钢中国建筑设计研究院有限公司胜景几何设计研究中心中国建筑设计研究院有限公司中国建科中国工程院

以北京隆福寺东院项目作为实例,探讨复合型建筑城市更新项目在深化设计阶段的设计方法。在复杂客观条件的多重考验下,常规深化设计方法在保证设计成果的深度与完成度方面暴露出局限性。设计团队对此进行了针对性创新,通过动态控制策略,... 详细信息

以北京隆福寺东院项目作为实例,探讨复合型建筑城市更新项目在深化设计阶段的设计方法。在复杂客观条件的多重考验下,常规深化设计方法在保证设计成果的深度与完成度方面暴露出局限性。设计团队对此进行了针对性创新,通过动态控制策略,在设计效果保持系统特征的前提下,将其拆解为多种相对独立的效果控制策略,获得设计的灵活度。旨在通过对本实例深化设计重点的展开,为探索以建筑师为主导的复合型建筑城市更新项目的高质量深化设计路径提供支撑。

关键词：复合型建筑城市更新项目深化设计路径动态控制策略高质量设计

“双碳目标下的建筑城市一体化与立体化关键技术研究”项目概述

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世界建筑 2024年第10期 10-14页

作者：李兴钢曹颖赵希翟建宇中国工程院中国建设科技集团中国建筑设计研究院有限公司

“双碳目标下的建筑城市一体化与立体化关键技术研究”(2023YFC3804100)项目属于“十四五”国家重点研发计划“城镇可持续发展关键技术与装备”重点专项。项目以多站点聚合的城市综合功能地段为主要研究对象,将构建、集成并示范建筑城... 详细信息

“双碳目标下的建筑城市一体化与立体化关键技术研究”(2023YFC3804100)项目属于“十四五”国家重点研发计划“城镇可持续发展关键技术与装备”重点专项。项目以多站点聚合的城市综合功能地段为主要研究对象,将构建、集成并示范建筑城市一体化与立体化成套设计方法和关键技术,为城市优化布局、完善功能、提高效能和转变发展方式提供科学量化依据,通过促进空间立体集约、交通动态优化、减碳技术集成的方式推动实现城市高质量发展及双碳目标。

关键词：双碳目标建筑城市一体化城市形态立体化

Effect of alloying on the properties of 9Cr low activation martensitic steels

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Acta Metallurgica Sinica(English Letters) 2010年第6期23卷 451-460页

作者： Rong MA Yafeng YANG Qingzhi YAN Ying YANG xinggang li Changchun GE Institute of Nuclear Materials University of Science and Technology Beijing Beijing 100083 China

Two types of 9Cr low activation martensitic steels （named 9Cr-1 and 9Cr-2） were developed in University of Science and Technology Beijing. 9Cr-1 and 9Cr-2 were produced by vacuum induction melting method, and examinations of the microstruc- tures were carried out with X-ray diffraction analysis, optical microscopy, scanning electron microscopy and transmission electron microscopy. The ultimate tensile strength and yield tensile strength were evaluated with tensile tests. The impact properties were characterized with Charpy impact experiments. The results indi- cated that 9Cr-1 and 9Cr-2 on as-received condition （95 ~C/30 min/water quenching plus 780 ~C/90 min/air cooling） were flflly martensitic steels free of ^-ferrite. The ul- timate tensile strength of 9Cr-1 and 9Cr-2 were 695 MPa and 680 MPa, respectively. However, 9Cr-2 showed a fine grain size of 4.8 pm, and its value of ductile-brittle transition temperature （DBTT） was -90 ~C under as-received condition. The additions of vanadium, titanium and boron accelerated the formation of MX precipitates and resulted in fine grains and precipitates. The fine grains effectively reduced the value of DBTT from -60 ℃ to -90 ℃ with identical upper shelf energy （USE）. The decrease in silicon concentration of 9Cr-2 induced a slight reduction in ultimate tensile strength from 695 MPa to 680 MPa.

关键词： 9Cr low activation martensitie steel Grain size Mechanical properties