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Influence of Plastic Deformation on Thermal Stability of Low Carbon Bainitic Steel

Journal of Iron and Steel Research International 2015年第1期22卷 60-66页

作者： Chao SUN shan-wu YANG Rui ZHANG xian WANG Hui GUO School of Materials Science and Engineering University of Science and Technology Beijing

Bainite is metastable due to its high dislocation density, and consequently bainitic steel structures have the problem of thermal stability. Plastic deformation of bainite can further increase dislocation density and change dislo- cation configuration at the same time. The influence of plastic deformation on thermal stability of low carbon bainitic steel during isothermal holding at 650 ℃ was investigated with hardness analysis, in-situ tracing metallographic analysis and transmission electron microscopy, Bainite in the low carbon steel evolves into polygonal ferrite via recov- ery and reerystallization during isothermal holding at 650 ℃. There is a considerably long period （about 20 h） be tween end of recovery and commencement of recrystallization of undeformed bainite, in which the hardness of the sample maintains a constant value slightly lower than that before reheating. Slight plastic deformation of bainite in- duces rearrangement of pre existing dislocations and forming of low-energy dislocation cells inside bainite laths, which has little influence on thermal stability of bainite, whereas heavy plastic deformation results in obvious dislocation multiplication and accelerates recrystallization of bainite. Recrystallization of heavily-deformed bainite occurs preferen tially at prior austenite grains boundaries. The samples subjected to heavy torsion exhibit obviously higher thermal stability than the samples subjected to heavy compression despite their same initial hardness, which can be attributed to different influences of torsion and compression on dislocations and boundaries of bainite.

关键词： bainite thermal stability plastic deformation compression torsion

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Engineering high-performance dielectric chiral shells with enhanced chiral fields for sensitive chiral biosensor

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Rare Metals 2024年第3期43卷 1197-1206页

作者： Yi-Fan Wang shan-shan Huang Zhen-Dong Dai Shi-Lin xian Xuan-Nan Wu Fu-Hua Gao Yi-Dong Hou College of Physics Sichuan UniversityChengdu610065China Graduate School of Sichuan University Sichuan UniversityChengdu610065China

Chiral metamaterials have been a topic of significant research interest in recent years due to their potential for various applications in nanophotonic devices and chiral ***,the intrinsic Ohmic loss in surface plasmonic resonance has limited their practical use,resulting in large light dissipation and weak chiroptical ***,we report on the development of high-performance dielectric chiral shells(DCS)through a two-step Si deposition process on a self-assembled microsphere *** form DCS sample completely oyercomes the cancelation effect originated from the disorder property of the micro-sphere monolayer in macroscale,and at a wavelength of approximately 710 nm,the measured optimal chiral signal(g-factor)and transmittance can reach up to 0.7 and 0.3,*** strong chiroptical effect comes from the asymmetric circular displacement currents(i.e.,magnetic modes)enabled by the specific shell *** chiral shell geometry,electromagnetic properties,sensor sensitivity of chiral molecules and figure of merit are systematically *** DCSs demonstrate highly sensitive detection of chiral biomolecules owing to their easily accessible geometry and enhanced uniform chiral field.

关键词： Dielectric chiral shells(DCS) Si deposition Magnetic resonance Highly sensitive sensor Chiral field

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Design strategies of Pd-based electrocatalysts for efficient oxygen reduction

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Rare Metals 2023年第6期42卷 1778-1799页

作者： Chun-Jie Li Guang-Cun shan Chun-xian Guo Ru-Guang Ma School of Materials Science and Engineering Suzhou University of Science and TechnologySuzhou215009China School of Instrumentation Science and Opto-electronics Engineering Beihang UniversityBeijing100083China

Oxygen reduction reaction(ORR) occurs at the cathode of fuel cells and metal-air batteries,but usually suffers from sluggish *** solve this issue,efficient electrocatalysts are highly ***(Pd)-based nanomaterials,as the most promising substitute of platinum(Pt),exhibit superior activity and stability in ORR *** delicate regulation of the structure and/or composition shows great potential in improving the electrocatalytic ORR performance of Pd-based *** this review,we retrospect the recent advance of Pdbased ORR electrocatalysts,and analyses the relationship between nanostructure and catalytic *** start with the ORR mechanism and indicators of ORR performance in both alkaline and acidic media,followed by the synthetic methods for Pd-based ***,we emphasize the design strategies of efficient Pd-based ORR catalysts from the perspective of composition,crystal phase,morphology,and support *** but not least,we conclude with possible opportunities and outlook on Pd-based nanomaterials toward ORR.

关键词： Oxygen reduction reaction(ORR) Palladium(Pd) Electrocatalyst Overpotential Reaction kinetics

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Effect of Rare Earth and Cooling Process on Microstructure and Mechanical Properties of an Ultra-Cleaned X80 Pipeline Steel

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Acta Metallurgica Sinica(English Letters) 2021年第5期34卷 639-648页

作者： He Duan Yi-Yin shan Ke Yang xian-Bo Shi Wei Yan Yi Ren Institute of Metal Research Chinese Academy of SciencesShenyang110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang110016China State Key Laboratory of Metal Materials and Application for Marine Equipment Anshan114009China

In order to explore the eff ect of a small amount of rare earth addition in ultra-cleaned pipeline steel and the influence of the cooling process on the tensile and impact properties,three API X80 pipeline steels were fabricated by varying RE addition and the cooling process at the same *** microstructures with different features for a low C high Nb microalloyed high-strength pipeline steel and the corresponding mechanical properties were *** results showed that even in the ultra-cleaned steel with O and S contents less than 10 ppm,the addition of RE would still cause an increase in the volume fraction of inclusions consisting of complicated RE oxysulfide and RE *** inclusions formed in the 112 ppm RE steel were harmful to the low temperature toughness,while few inclusions formed in the 47 ppm RE steel had almost no influence on the low temperature *** two RE additions had no effect on strength of the *** the finishing cooling temperature was increased and the cooling rate was decreased within a certain range,the volume fractions of polygonal ferrite and quasi-polygonal ferrite as well as the number density and size of martensite–austenite islands were *** such combined effect,the strength of the steels had almost no *** the finishing cooling temperature was increased from 481 to 584℃and the cooling rate was reduced from 20 to 13℃/s,for the steel with 112 ppm addition of RE,there was an obvious decrease in the low temperature *** reduced value(about 33 J)of the USE of steel consisted of two parts including the influence(about 18 J)of more inclusions formed due to 112 ppm addition of RE and the eff ect(about 15 J)of the lower high-angle grain boundaries.

关键词： Low temperature toughness Cooling process High-angle grain boundaries(HAGBs) Ductile–brittle transition temperature(DBTT) Rare earth Inclusions

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Effect of thermal annealing on the microstructure, mechanical properties and residual stress relaxation of pure titanium after deep rolling treatment

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Journal of Materials Science & Technology 2019年第3期35卷 409-417页

作者： Jie Huang Kai-Ming Zhang Yun-Fei Jia Cheng-Cheng Zhang xian-Cheng Zhang xian-Feng Ma shan-Tung Tu Key Laboratory of Pressure Systems and Safety Ministry of Education School of Mechanical and Power Engineering East China University of Science and Technology AECC Commercial aircraft Engine Co. Ltd. Shanghai Engineering Research Center for Commercial Aircraft Engine Sino-French Institute of Nuclear Engineering and Technology SunYat-Sen University

The aim of this paper was to investigate the effect of thermal annealing on the microstructure, mechanical properties, and residual stress relaxation of deep rolled pure titanium. The microstructure and mechanical properties of the surface modified layer were analyzed by metallographic microscopy, transmission electron microscope and in-situ tensile testing. The results showed that the annealed near-surface layer with fine recrystallized grains had increased ductility but decreased strength after annealing below the recrystallization temperature, where the tensile strength was still higher than that of the substrate. After annealing at the recrystallization temperature, the recrystallized near-surface layer had smaller grain size,similar tensile strength, and higher proportional limit, comparable to those of the substrate. Moreover, the residual stress relaxation showed evidently different mechanisms at three different temperature regions:low temperature(T≤ 0.2 Tm), medium temperature(T≈(0.2–0.3) Tm), and high temperature(T≥ 0.3 Tm).Furthermore, a prediction model was proposed in terms of modification of Zener-Wert-Avrami model,which showed promise in characterizing the residual stress relaxation in commercial pure Ti during deep rolling at elevated temperature.

关键词： Deep rolling Ultra-fine grain Tensile strength Microstructure Residual stress

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On-chain is not enough:Ensuring pre-data on the chain credibility for blockchain-based source-tracing systems

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Digital Communications and Networks 2023年第5期9卷 1053-1060页

作者： Yilei Wang Zhaojie Wang Guoyu Yang shan ai Xiaoyu xiang Chang Chen Minghao Zhao School of Computer Science Qufu Normal UniversityRizhao276826China Guangxi Key Laboratory of Cryptography and Information Security Guilin University of Electronic TechnologyGuilin541004China Institute of Artificial Intelligence and Blockchain Guangzhou UniversityGuangzhou510006China School of Software Tsinghua UniversityTsinghua UniversityBeijing100191China

The blockchain provides a reliable and scalable method for enabling source-tracing functionality in large-scale Internet of Things(IoT)*** blockchain-based source tracing applications are generally based on the hypothesis that the raw data collected by each IoT node are credible and consistent,which however may not always be the *** no mechanism ensures the reliability of the original data collected from the IoT devices,these data may be accidently screwed up or maliciously tampered with before they are uploaded *** address this issue,we propose the Multi-dimensional Certificates of Origin(MCO)method to filter out the potentially incredible data-till all the data uploaded to the chain are *** achieve this,we devise the Multidimensional Information Cross-Verification(MICV)and Multi-source Data Matching Calculation(MDMC)*** verifies whether a to-be-uploaded datum is consistent or credible,and MDMC determines which data should be discarded and which data should be kept to retain the most likely credible/untampered ones in the circumstance when data inconsistency ***-scale experiments show that our scheme ensures on the credibility of data and off the chain with an affordable overhead.

关键词： Blockchain Traceability Blockchain security

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Sea surface temperature retrieval based on simulated microwave polarimetric measurements of a one-dimensional synthetic aperture microwave radiometer

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Acta Oceanologica Sinica 2021年第3期40卷 122-133页

作者： Mengyan Feng Weihua ai Wen Lu Chengju shan Shuo Ma Guanyu Chen College of Meteorology and Oceanography National University of Defense TechnologyNanjing 211101China Zhejiang University of Water Resources and Electric Power Hangzhou 310000China PLA Troop 32033 Haikou 570100China

Compared with traditional real aperture microwave radiometers,one-dimensional synthetic aperture microwave radiometers have higher spatial *** this paper,we proposed to retrieve sea surface temperature using a one-dimensional synthetic aperture microwave radiometer that operates at frequencies of 6.9 GHz,10.65 GHz,18.7 GHz and 23.8 GHz at multiple incidence *** used the ERA5 reanalysis data provided by the European Centre for Medium-Range Weather Forecasts and a radiation transmission forward model to calculate the model brightness *** brightness temperature measured by the spaceborne one-dimensional synthetic aperture microwave radiometer was simulated by adding Gaussian noise to the model brightness ***,a backpropagation(BP)neural network algorithm,a random forest(RF)algorithm and two multiple linear regression algorithms(RE1 and RE2)were developed to retrieve sea surface temperature from the measured brightness temperature within the incidence angle range of 0°-65°.The results show that the retrieval errors of the four algorithms increase with the increasing Gaussian *** BP achieves the lowest retrieval errors at all incidence *** retrieval error of the RE1 and RE2 decrease first and then increase with the incidence angle and the retrieval error of the RF is contrary to that of RE1 and RE2.

关键词： one-dimensional synthetic aperture microwave radiometer sea surface temperature retrieval neural network random forest multiple linear regression

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Noise Effects on Oscillator Network of Transcription Regulators

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Communications in Theoretical Physics 2002年第10期38卷 497-502页

作者： WANG xian-Ju ai Bao-Quan LIU Guo-Tao LIU Liang-Gang Department of Physics Zhongshan University Guangzhou 510275 China Department of Physics Zhongshan University Guangzhou 510275 China Department of Physics Zhongshan University Guangzhou 510275 China Department of Physics Zhongshan University Guangzhou 510275 China

Based on the model describing the regulation of the PRM operator region of λ phage proposed by Jeff Hastyet al., we study the noise effects on the oscillator network. We find that the additive noise cannot change the period andthe amplitude of the relaxation oscillator, but in the multiplicative case, the period of the relaxation oscillator increasesto a constant value with the increase of the strength of noise, and the amplitude of the relaxation oscillator also showsincreases with the increase of the strength of noise. This novel results suggest that an external multiplicative noise sourcecould be used to control gene expression.

关键词： gene control, noise strength, oscillator

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Physical simulation of rock burst induced by stress waves

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Journal of China University of Mining and Technology 2008年第3期18卷 401-405页

作者： LU ai-hong MAO xian-biao LIU Hai-shun School of Sciences China University of Mining ＆ Technology Xuzhou Jiangsu 221008 China

The behavior of stress wave propagation in rock walls and the process of rock bursts were simulated by application tests of material similar to rock. Results show that 1) the attenuation characteristics of stress waves were related to the material proper-ties, stress waves attenuate more quickly in soft material and 2) when the explosion load was applied at the top of the roadway, the number and the length of the cracks increased with a decrease in the distance between the explosive point and roof of the roadway. When the distance was 280 mm, only some chips appeared near the source, when the distance was 210 mm, some small cracks started to appear near the road-rib and when the distance was reduced to 140 mm, larger cracks appeared at the road-rib. It can be concluded that, under a given stress the number of cracks is closely related to the intensity of stress waves. The cracks in the sur-rounding rock can be reduced by controlling the intensity of the stress waves and rock bursts can be avoided to some extent by pre-venting the formation of layered crack structures. A new experimental approach has been provided for studying rock bursts by using physical simulation.

关键词： similar material stress wave physical simulation rock burst

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A novel hole cold-expansion method and its effect on surface integrity of nickel-based superalloy

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Journal of Materials Science & Technology 2020年第24期59卷 129-137页

作者： xianCao Ping ZhangShuang Liu Xue-Lin Lei Run-Zi Wang xian-Cheng Zhang shan-Tung Tu Key Laboratory of Pressure Systems and Safety Ministry of EducationSchool of Mechanical and Power EngineeringEast China University of Science and TechnologyShanghai 200237China

Preferred surface integrity around the hole wall is one of the key parameters to ensure the optimized performance of hole components for nickel-based *** novel hole cold expansion technique introduced in this work involves the laser texturing process(LTP)followed by the Hertz contact rotary expansion process(HCREP),where the cylindrical sleeve is the critical component connecting the abovementioned two *** purpose of LTP is to obtain the most optimized strengthened cylindrical sleeve surface,preparing for the following ***,the HCREP acts on the nickel-based hole components by the rotary extruding movements of the strengthened sleeve and conical mandrel *** compared to the as-received GH4169 material,the surface integrity characterization for the strengthened hole shows that a plastic deformation layer with finer grains,higher micro-hardness,deeper compressive residual stress(CRS)distribution and lower surface roughness is formed at the hole *** addition,transmission electron microscope(TEM)observations reveal the microstructure evolution mechanism in the strengthened *** refinement near the hole wall is regarded as the fundamental reason for improving the surface integrity,where the aggregated dislocations and recombined dislocation walls can be clearly observed.

关键词： Cold expansion process Laser texturing process Surface integrity Microstructure evolution

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