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Microstructure and Mechanical Properties of X80 Pipeline Steel Joints by Friction Stir Welding Under Various Cooling Conditions

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Acta Metallurgica Sinica(English Letters) 2020年第1期33卷 88-102页

作者： G.M.Xie R.h.Duan P.Xue Z.Y.ma h.L.Liu Z.A.Luo State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China Shenyang National Laboratory for materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

X80 pipeline steel plates were friction stir welded(FSW)under air,water,liquid CO2+water,and liquid CO2 cooling conditions,producing defect-free *** microstructural evolution and mechanical properties of these FSW joints were *** granular bainite was observed in the nugget zone(NZ)under air cooling,and lath bainite and lath martensite increased signifi cantly as the cooling medium temperature *** particular,under the liquid CO2 cooling condition,a dual phase structure of lath martensite and fi ne ferrite appeared in the *** to the case under air cooling,a strong shear texture was identifi ed in the NZs under other rapid cooling conditions,because the partial deformation at elevated temperature was retained through higher cooling *** liquid CO2 cooling,the highest transverse tensile strength and elongation of the joint reached 92%and 82%of those of the basal metal(BM),respectively,due to the weak tempering softening.A maximum impact energy of up to 93%of that of the BM was obtained in the NZ under liquid CO2 cooling,which was attributed to the operation of the dual phase of lath martensite and fi ne ferrite.

关键词： Friction stir welding Pipeline steel Microstructure Mechanical properties Cooling

Real-time vehicle-to-grid control for frequency regulation with high frequency regulating signal

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Protection and Control of Modern Power Systems 2018年第1期3卷 151-158页

作者： h.Liu K.huang Y.Yang h.Wei S.ma College of Electrical Engineering Guangxi UniversityNanning 530004China China Electric Power Research Institute Beijing 100192China

The large-scale popularization of electric vehicles(EVs)brings the potential for grid frequency *** the characteristics of fast response and adjustment of EVs,two control strategies of automatic generation control(AGC)with EVs are proposed responding to two high frequency regulating signals extracted from area control error(ACE)and area regulation requirement(ARR)by a digital filter,*** order to dispatch regulation task to EVs,the capacity of regulation is calculated based on maximum V2G power and the present V2G power of ***,simulations based on a two-area interconnected power system show that the proposed approaches can significantly suppress frequency deviation and reduce the active power output of traditional generation units.

关键词： Area control error(ACE) Automatic generation control(AGC) Electric vehicle Frequency regulation high frequency regulating signal

Experimental and Numerical Investigation of an End Plate Connection with Using Long Shank Sma Bolts

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Journal of harbin Institute of Technology(New Series) 2015年第3期22卷 22-30页

作者： hongwei ma Yongbing Zhu Michael C.h.Yam Yang Wang School of Civil Engineering and Transportation South China University of Technology State Key Laboratory of Subtropical Architecture Science South China University of Technology Department of Building and Real Estate The Hong Kong Polytechnic University

Superelastic shape memory alloys( Smas) have the ability to recover their original shape after experiencing large strains. End-plate connection with using superelastic long shank Sma bolts is proposed in this paper. By using strong beam-weak bolt cluster design methodology and special configurations to strength beam ends,a superelastic hinge is expected to form in column flange. To validate the mechanical behavior of the proposed beam-to-column connection,both quasi-static tests and numerical analysis are conducted with cyclic transverse loads applied on the beam ends. The results indicate the connection deformations concentrate on the long shank Sma bolts upon loading and the bolt cluster rotates around the axis near beam flange. By using the super elastic effect,the Sma bolts recover most elongations and the connection recovers to its original shape after experiencing 0. 02 rad interstorey drift angle. The connection shows obvious self-centering properties.

关键词： finite element connection shape memory alloy ductility self-centering

Structure evolution of the Fe_(3)C/Fe interface mediated by cementite decomposition in cold-deformed pearlitic steel wires

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Journal of materials Science & Technology 2022年第6期101卷 28-36页

作者： Y.T.Zhou X.h.Shao S.J.Zheng X.L.ma Shenyang National Laboratory for materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Tianjin Key Laboratory of materials Laminating Fabrication and Interface Control Technology School of Materials Science and EngineeringHebei University of TechnologyTianjin 300130China

Cold-drawn pearlitic steel wire is irreplaceably used in industry owing to its outstanding mechanical property which is dominated by the cementite/ferrite(Fe_(3)C/Fe) interfaces in the material. however, the fine structures of the Fe3C/Fe interfaces in the deformed wires are less known to date. In this work, transmission electron microscopic investigation was performed on the atomic structures of the interfaces with the Isaichev orientation relationship(OR) in the wires with progressive deformation strains. In addition to the effect of the dislocation/interface interactions, this work revealed that the deformation-induced partial decomposition of cementite plays an important role in the interface reconstruction during deformation. The interfacial carbon vacancies generated by cementite decomposition and particularly, the amorphization of cementite layers in the sample with ε > 1 could effectively annihilated the interfacial dislocations and consequently relaxed the interfacial stress. The correlations between the interface structure changes and the mechanical properties of the wires were discussed.

关键词： Pearlitic steel Cementite decomposition Interface structure Deformation Transmission electron microscopy

A survey of learning-based robot motion planning

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IET Cyber-Systems and Robotics 2021年第4期3卷 302-314页

作者： Jiankun Wang Tianyi Zhang Nachuan ma Zhaoting Li han ma Fei Meng max Q.-h.Meng Department of Electronic and Electrical Engineering Southern University of Science and TechnologyShenzhenChina Department of Electronic Engineering The Chinese University of Hong KongHong KongChina Shenzhen Research Institute of the Chinese University of hong Kong ShenzhenChina

A fundamental task in robotics is to plan collision-free motions among a set of ***,learning-based motion-planning methods have shown significant advantages in solving different planning problems in high-dimensional spaces and complex *** article serves as a survey of various different learning-based methods that have been applied to robot motion-planning problems,including supervised,unsupervised learning,and reinforcement *** learning-based methods either rely on a human-crafted reward function for specific tasks or learn from successful planning *** classical definition and learning-related definition of motion-planning problem are provided in this *** learning-based motion-planning algorithms are introduced,and the combination of classical motion-planning and learning techniques is discussed in detail.

关键词： robot learning motion

Different Diffusion Behavior of Cu and Ni Undergoing Liquidesolid Electromigration

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Journal of materials Science & Technology 2014年第12期30卷 1235-1242页

作者： M.L.huang Z.J.Zhang h.T.ma L.D.Chen Electronic Packaging materials Laboratory School of Materials Science & Engineering Dalian University of Technology IC Packaging Department Xi'an Institute of Microelectronic Technology

The diffusion behavior of Cu and Ni atoms undergoing liquidesolid electromigration（L-S EM） was investigated using Cu/Sn/Ni interconnects under a current density of 5.0 103A/cm2 at 250℃. The flowing direction of electrons significantly influences the cross-solder interaction of Cu and Ni atoms, i.e., under downwind diffusion, both Cu and Ni atoms can diffuse to the opposite interfaces; while under upwind diffusion,Cu atoms but not Ni atoms can diffuse to the opposite interface. When electrons flow from the Cu to the Ni, only Cu atoms diffuse to the opposite anode Ni interface, resulting in the transformation of interfacial intermetallic compound（IMC） from Ni3Sn4into（Cu,Ni）6Sn5and further into [（Cu,Ni）6Sn5t Cu6Sn5], while no Ni atoms diffuse to the opposite cathode Cu interface and thus the interfacial Cu6Sn5 *** electrons flow from the Ni to the Cu, both Cu and Ni atoms diffuse to the opposite interfaces,resulting in the interfacial IMC transformation from initial Cu6Sn5into（Cu,Ni）6Sn5and further into[（Cu,Ni）6Sn5t（Ni,Cu）3Sn4] at the anode Cu interface while that from initial Ni3Sn4into（Cu,Ni）6Sn5and further into（Ni,Cu）3Sn4at the cathode Ni interface. It is more damaging with electrons flowing from the Cu to the Ni than the other way.

关键词： Cu/Sn/Ni Electromigration Cross-solder interaction Interfacial reaction Diffusion

Effect of alloying elements on mechanical properties in Cu-15%Cr in-situ composites

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中国有色金属学会会刊：英文版 2004年第2期14卷 284-290页

作者： h.G.Suzuki J.ma K.Mihara S.Sakai S.Sun Japan Society for Promotion of Science Department of Materials Science and EngineeringFurukawa Electric COFurukawa Electric CONational Institute for Materials Science 4-1-8 Hon-machi Kawaguchi332-0012 JapanDepartment of Materials Science and EngineeringTsinghua UniversityBeijing 100084 China Tsinghua UniversityBeijing 100084China LTDNikko 321-0014JapanLTDNikko 321-0014JapanTsukuba 305-0047Japan

The effects of alloying elements on the mechanical properties as well as electrical conductivity in Cu-15%Cr(mass fraction) in-situ composites were systematically studied and high strength and high electrical conductive Cu base in-situ composites have been developed. The best combination is the addition of 0.1% to 0.2% Zr, Ti, or Sn in Cu-15%Cr in-situ composite, thermomechanical treatment to refine the microstructure and optimizing the precipitation of second phase. The strength is controlled by high density of dislocations in the Cu matrix, the lamellar spacing of the second phase, and the fine Cr precipitates. The aging treatment to reduce solute atoms has a beneficial effect on the increase of electrical conductivity. The addition of Zr, or Ti of about 0.15% to 0.2% promotes the precipitation of Cr particles.

关键词： CuCr合金铜合金内生复合材料机械性能合金化电导率

Numerical study of convective heat transfer of a supersonic combustor with varied inlet flow conditions

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Acta Mechanica Sinica 2019年第5期35卷 943-953页

作者： W.h.Fan F.Q.Zhong S.G.ma X.Y.Zhang State Key Laboratory of high Temperature Gas Dynamics Institute of MechanicsChinese Academy of SciencesBeijing 100190 China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China

Characteristics of convective heat transfer of a supersonic model combustor with variable inlet flow conditions were studied by numerical simulation in this *** three-dimensional flow and wall heat flux at different air inlet mach numbers of 2.2,2.8 and 3.2 were studied numerically with Reynolds-averaged Navier-Stokes equations with a shear-stress transport(SST)k-ωturbulence model and a three-step reaction ***,ethylene was chosen as the fuel,and the fixed fuel-to-air equivalence ratio is 0.8 in all cases in this *** results of the simulations indicate that wall heat flux distribution of the combustor is very non-uniform with several peaks of wall heat flux at varied *** the low inlet mach number of 2.2,a shock train structure is formed in the isolator,and three peaks of wall heat flux are located respectively on the backward face of the cavity,on the side wall near the fuel injection and on the bottom wall near the injection holes,and a maximum wall heat flux reaches 5.4 MW/*** the medium inlet mach number of 2.8,there exists a much shorter shock structure with three peaks of wall heat flux similar to that of mach number ***,as the inlet mach number increased to 3.2,there is no shock structure upstream of fuel injections,and the combustor flow is in a supersonic mode with different locations and values of wall heat flux *** statistical results of wall heat loading show that the change of total wall heat is not monotonic with the increase of inlet mach number,and the maximum appears in the case of mach number being ***,for all the cases,the bottom wall takes up more than 50%of the total heat loading.

关键词： Wall heat flux Numerical simulation Ethylene Supersonic combustor

MICROSTRUCTURE ANALYSIS AND MEChANICAL PROPERTIES OF Zn-Al ALLOY ROD PRODUCED BY hEATED MOLD CONTINUOUS CASTING

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Acta Metallurgica Sinica(English Letters) 2003年第3期16卷 241-248页

作者： Y.ma Y.hao F.Y.Yan h.J.Liu State Key Laboratory of Advanced Nonferrous materials Lanzhou University of Science & Technology Lanzhou 730050 ChinaState Key Laboratory of Advanced Nonferrous Materials Lanzhou University of Science & Technology Lanzhou 730050 ChinaState Key Laboratory of Advanced Nonferrous Materials Lanzhou University of Science & Technology Lanzhou 730050 ChinaSchool of Mechano-Electronic EngineeringHua Qian University Quanzhou 362011China

The new technology of continuous casting by heated mold was used to produce directional solidification ZA alloy lines to eliminate the inter defects of these lines and increase their mechanical properties. The results are as follows: (1) The microstruc-ture of the ZA alloy lines is the parallel directional dendritic columnar crystal. Every dendritic crystal of eutectic alloy ZA5 was composed of many layer eutectic β and η phases. The micro structure of hypereutectic ZA alloys is primary dendritic crystal and interdendritic eutectic structure. The primary phase of ZA8 and ZA12 is β, among them, but the primary phase of ZA22 and ZA27 is a. (2) Through the test to the as-cast ZA alloy lines made in continuous casting by heated mold, it is found that the tensile strength and hardness increase greatly, but the elongation decreases. With the increase of aluminum amount from ZA 5 to ZA 12, ZA22 and ZA27, the tensile strength increases gradually. ZA27 has the best comprehensive mechanical properties in these four kinds of ZA alloys. (3) heat treatment can decrease the dendritic segregation and improve the elongation of ZA alloy, but make their strength decrease slightly.

关键词： zinc-aluminum alloy heated mold continuous casting mechanical properties heat treatment