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Application of phase diagram calculations to development of new ultra-high temperature structural materials

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中国有色金属学会会刊：英文版 2007年第6期17卷 1396-1404页

作者：杨莹 B.P. Bewlay 陈双林 Y.A. Chang CompuTherm LLC Madison Wisconsin 53719 USA general electric global research Schenectady New York 12301 USA Department of Materials Science and Engineering University of Wisconsin-Madison Madison Wisconsin 53705 USA

In-situ refractory metal intermetallic composites(RMICs) based either on (Nb, Si) or (Mo, Si, B) are candidate materials for ultra-high temperature applications (>1400 ℃). To provide a balance of mechanical and environmental properties, Nb-Si composites are typically alloyed with Ti and Cr, and Mo-Si-B composites are alloyed with Ti. Phase diagrams of Nb-Cr-Ti-Si and Mo-Si-B-Ti, as prerequisite knowledge for advanced materials design and processing development, are critically needed. The phase diagrams in the metal-rich regions of multicomponent Nb-Cr-Ti-Si and Mo-Si-B-Ti were rapidly established using the Calphad (Calculation of phase diagram) approach coupled with key experiments. The calculated isotherms, isopleths, and solidification paths were validated by experimental work. The important heterogeneous multiphase equilibria in both quaternary systems identified will offer engineers the opportunity to develop materials with a balance of properties for high-temperature applications.

关键词：金属间化合高温材料 Mo-Si-B-Ti Nb-Cr-Si-Ti

Impedance Analysis Considering Unstable Subsystem Poles for MMC-HVDC-based Wind Farm Integration System

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CSEE Journal of Power and Energy Systems 2022年第2期8卷 634-639页

作者： Ke Ji Hui Pang Shan Liu Guangfu Tang China electric Power research Institute Beijing100192China global Energy Interconnection research Institute Beijing 102211China

Employing the AC/DC impedance analysis method,extensive research has been conducted on issues pertaining to harmonic resonance observed in wind farm-connected MMCHVDC systems over the past 5 *** general,this method divides the studied system into two subsystems at AC and DC ***,the impedance produced by these subsystems can be used to determine the system stability by implementing Nyquist criterion or generalized Nyquist stability ***,the existing impedance analysis methods usually assume the subsystems to be stable and disregard certain special cases with potentially unstable subsystems,where the unstable poles of these subsystems must be evaluated before applying Nyquist *** view of this consideration,a simplified method for identifying unstable subsystem poles is presented in this ***,the shortcoming of existing impedance analyses is rectified by considering the unstable subsystem *** proposed method and the stability analyses are validated by the electromagnetic transient simulation performed in PSCAD/EMTDC.

关键词： AC/DC side impedance method harmonic resonance MMC-HVDC small-signal stability wind farm

research on big data applications in global Energy Interconnection

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global Energy Interconnection 2018年第3期1卷 352-357页

作者： Dongxia Zhang Robert Caiming Qiu China electric Power research Institute Shanghai Jiao Tong University Tennesse Technological University

Construction of global Energy Interconnection(GEI) is regarded as an effective way to utilize clean energy and it has been a hot research topic in recent years. As one of the enabling technologies for GEI, big data is accompanied with the sharing, fusion and comprehensive application of energy related data all over the world. The paper analyzes the technology innovation direction of GEI and the advantages of big data technologies in supporting GEI development, and then gives some typical application scenarios to illustrate the application value of big data. Finally, the architecture for applying random matrix theory in GEI is presented.

关键词： global Energy Interconnection Big data Clean energy Random matrix theory

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generalization performance of a deep learning based engine-out emissions model

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Energy and AI 2021年第3期5卷 325-329页

作者： Alok Warey Jian Gao Ronald O.Grover Jr. general Motors global research and Development 30500 Mound RoadWarrenMI 48090United States

In our previous work[1],an ensemble of Convolutional Neural Network(CNN)models was used to predict engine-out emissions of Carbon Monoxide(CO),Unburned Hydrocarbons(HC)and Smoke directly from in-cylinder con-tours of multiple scalar fields-Equivalence Ratio,Temperature,Velocity and Turbulent Kinetic Energy(TKE)at Exhaust Valve Opening(EVO)generated by physics based Computational Fluid Dynamics(CFD)simulations and experimentally measured emissions data.A dataset of 600 CFD generated images,one for each engine operating condition,from a 1.6L light-duty diesel engine was used for training,validation and testing of the CNN ensemble *** this short communication,several modifications were made to the image data generation and training *** ensemble of CNN models was re-trained per the new procedure on the modified image dataset from the 1.6L *** generalization capability of this re-trained deep learning model was investigated by evaluating its prediction performance on a test dataset from a 3.0L diesel engine that was not used previously for training,validation or *** CNN ensemble model re-trained on the 1.6L engine dataset captured the qual-itative trends for all three emissions species on the 3.0L engine test dataset,however,quantitatively its prediction performance was not as *** work with additional engines and input features is planned to improve the generalization performance of the CNN based emissions prediction model.

关键词： performance prediction engine

Effect of hot-humid exposure on static strength of adhesive-bonded aluminum alloys

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Defence Technology（防务技术） 2015年第3期11卷 220-228页

作者： Rui ZHENG Jian-ping LIN Pei-Chung WANG Yong-Rong WU School of Mechanical Engineering Tongji University global research & Development Center General Motors Corporation

The effect of hot-humid exposure(i.e., 40 C and 98% R.H.) on the quasi-static strength of the adhesive-bonded aluminum alloys was studied. Test results show that the hot-humid exposure leads to the significant decrease in the joint strength and the change of the failure mode from a mixed cohesive and adhesive failure with cohesive failure being dominant to adhesive failure being dominant. Careful analyses of the results reveal that the physical bond is likely responsible for the bond adhesion between L adhesive and aluminum substrates. The reduction in joint strength and the change of the failure mode resulted from the degradation in bond adhesion, which was primarily attributed to the corrosion of aluminum substrate. In addition, the elevated temperature exposure significantly accelerated the corrosion reaction of aluminum, which accelerated the degradation in joint strength.

关键词：铝合金粘接静强度粘结破坏接头强度粘结强度腐蚀反应静态强度

Sequential auto-reclosing strategy for hybrid HVDC breakers in VSC-based DC grids

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Journal of Modern Power Systems and Clean Energy 2019年第3期7卷 633-643页

作者： Xiangyu PEI Guangfu TANG Shengmei ZHANG China electric Power research Institute Beijing100192China global Energy Interconnection research Institute Co.Ltd. Beijing102209China North China electric Power University Beijing102206China

The use of overhead lines for power transmission in the future high-voltage and large-capacity voltagesource converter(VSC)-based direct current(DC) grid will significantly increase the probability of temporary *** eliminate potential adverse impacts such as erroneous protection, line-insulation failure, and even damage to power electronic devices resulting from a DC breaker reclosing operation with the traditional sequential autoreclosing strategy, a new sequential auto-reclosing strat-egy for hybrid HVDC breakers(HHBs) in VSC-based DC grids is proposed. This strategy is based on the step-by-step operation of the transfer branch in the HHB. As a result,du/dt resulting from the HHB reclosing operation is greatly reduced, and therefore those potential negative impacts can be eliminated. Several other advantages are also *** feasibility and validity of the proposed strategy are verified in a four-terminal annular VSC-based DC grid electromagnetic transient model.

关键词： Overhead line Voltage-sourced converter(VSC)-based direct current grid Temporary fault Hybrid HVDC breaker(HHB) Auto-reclosing strategy

Enhancing Fe content tolerance in A356 alloys for achieving low carbon footprint aluminum structure castings

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Journal of Materials Science & Technology 2023年第30期161卷 180-191页

作者： Guodong Niu Jianfeng Wang Jinwen Ye Jian Mao College of Materials Science and Engineering Sichuan UniversityChengdu 610065China China Science Lab General Motor’s Global Research and DevelopmentShanghai 201206China

Low carbon footprint aluminum structure castings are the mainstream development direction of alu-minum alloys in the *** the Fe content tolerance upper limit in casting aluminum alloys is considered an effective way to promote the application of recycled aluminum *** this work,it was found that with the Ce and TiCN NPs(nanoparticles)addition simultaneously to A356 alloys,the acicular Fe-rich phases(β-Al 5 FeSi)which damages the properties can be changed into beneficial phases(core-shell heterostructures)for the alloy,and hence the mechanical properties of A356 alloys can be *** TiCN nanoparticles and rare element Ce play crucial roles in the formation of core-shell *** formation mechanism of core-shell heterostructure was also systematically researched from the perspective of thermodynamics and *** study provides a simple and feasible strategy to eliminate the harmful effects of Fe impurity and contributes to the industrialization of low carbon footprint aluminum structure castings.

关键词： A356 casting aluminum alloys Heterostructure Carbon neutral TiCN nano particles Mechanical properties

Low‑Carbon‑Emission Hot Stamping:A Review from the Perspectives of Steel Grade,Heating Process,and Part Design

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Automotive Innovation 2023年第3期6卷 324-339页

作者： Zeran Hou Yi Liu Qi He Jianfeng Wang Junying Min School of Mechanical Engineering Tongji UniversityShanghai 201804China China Science Lab General Motors Global Research and DevelopmentShanghai 201206China

Hot stamping steels have become a crucial strategy for achieving lightweighting and enhancing crash safety in the automo-tive industry over the past two ***,the carbon emissions of the materials and their related stamping processes have been frequently *** is essential to consider these emissions during the design *** materials and technologies in hot stamping pose challenges to the automotive industry's future development in carbon emission *** review discusses the promising materials for future application and their special features,as well as the emerging manufacturing and part design processes that have extended the limit of application for new *** heating processes and corresponding equipment have been proven to improve heating efficiency and control temperature *** material utilization and the overall performance of the components are improved by tailored blanks and an integrated part design *** achieve low-carbon-emission(LCE)hot stamping,it is necessary to systematically consider the steel grade,heating process,and part design,rather than solely focusing on reducing carbon emissions during the manufacturing process *** review aims to present the latest progress in steel grade,heating process,and part design of hot stamping in the automotive industry,providing solutions for LCE from a holistic perspective.

关键词： Low-carbon-emission Hot stamping Steel grade Heating process Part design

Effect of retained austenite on the fracture behavior of a novel press-hardened steel

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Journal of Materials Science & Technology 2023年第4期135卷 34-45页

作者： Zhisong Chai Qi Lu Jun Hu Lingyu Wang Zhou Wang Jianfeng Wang Wei Xu State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China China Science Laboratory General Motors Global Research&DevelopmentShanghai 201206China

Tensile and bending properties are two critical attributes of press hardened steels(PHSs)for automotive body structural ***,the research on these properties of PHSs with retained austenite(RA),which is introduced to improve the mechanical properties,has not been well *** this study,the effect of RA on the quasi-static uniaxial tensile and three-point bending behaviors has been systematically investigated for a newly developed Cr and Si alloyed *** with various degrees of mechanical stabilities was obtained by tuning the auto-tempering of martensite through the control of the die contact pressure during the press hardening *** stable RA provides the optimal combination of tensile and bending performance,while the PHS with RA of poor mechanical stability has a deteriorated bending toughness as manifested by a reduction of bending angle from approximately 61.6°to56.8°.However,itstensileproperties,incontrast,arethebestintermsof theproductofulti-mate tensile strength and total elongation(15.9 GPa%).This is mainly attributed to the unstable RA on the outermost surface of the bending *** unstable RA can easily transform into brittle martensite under local plane strain and strain gradient conditions in the bending test compared with uniaxial stress in the tensile test,promoting crack initiation and ***,the effect of martensitic auto-tempering or contact pressure on the quantity and stability of RA are also *** study would provide a useful reference to guide hot stamping process optimization for the newly developed Cr and Si-containing press-hardened steel.

关键词： Press-hardened steel Retained austenite Tensile property Bending toughness Crack initiation