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Microstructures and Mechanical Properties of Si-AI-Mn TRIP Steel with Niobium

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Journal of Materials Science & Technology 2007年第6期23卷 790-794页

作者： Zhengyou TANG hua ding Linxiu DU Long LI College of Materials and Metallurgy State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110004 China State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110004 China.

Microstructure consisting of ferrite, bainite and retained austenite can be obtained through intercritical annealing and isothermal treatment in bainite transformation region for low silicon TRIP （transformation induced plasticity） steel containing niobium. Effects of strain rate, Nb content and soaking temperature in bainite region on microstructure and mechanical properties of test steels were investigated. It is shown that as strain rate ranges from 10^-2 to 10^-4 s^-1, the volume fraction of transformed martensite from retained austenite, as well as tensile strength, elongation rate and strength-ductility product, increases. When Nb is added, the volume fraction of retained austenite decreases, but tensile strength and yield strength increase. While Nb content reaches 0.014%, the steel exhibits high elongation and combination of strength and ductility. Higher retained austenite volume fraction and good mechanical properties are obtained in the test steels when the soaking temperature in bainite region is 400℃. The maximum values of tensile strength, total elongation rate and strength-ductility product can reach 739 MPa, 38% and 28082 MPa%, respectively.

关键词： TRIP Strain rate Niobium content Retained austenite Mechanical properties

Research on the intelligent design system for investment casting die of aero-engine turbine blade based on knowledge

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航空动力学报 2010年第5期25卷 1061-1067页

作者： JIANG Rui-song ZHANG ding-hua WANG Wen-hu The Key Laboratory of Contemporary Design and Integrated Manufacturing Ministry of EducationSchool of Mechanical EngineeringNorthwestern Polytechnical UniversityXi'an 710072China

To solve the problems in turbine blade investment casting die design process such as long design time,lacking of expert experience and low level of intelligence,knowledge-based engineering (KBE) was introduced in the turbine blade investment casting die design field. The key technologies of the intelligent design method were researched and a prototype system was developed. A hybrid reasoning model was prompted in which case-based reasoning (CBR) was applied to conceptual design and rule-based reasoning (RBR) was applied to parts design after research the design process and domain knowledge of casting die. In the conceptual design stage,a retrieval model which integrated nearest neighbor approach and knowledge-based retrieval approach was prompted to improve the retrieval efficiency. Meanwhile,RBR was used to modify the retrieval result. The practical application results indicate that this system can reuse the expert experience efficiently and heighten the die design efficiency and quality.

关键词： turbine blade investment casting die intelligent design knowledge-based engineering (KBE)

Interfacial microstructure and mechanical properties of stainless steel clad plate prepared by vacuum hot rolling

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Journal of Iron and Steel Research International 2018年第7期25卷 732-738页

作者： Jun Jiang hua ding Zong-an Luo Guang-ming Xie School of Materials and Metallurgy Northeastern University Shenyang 110819 Liaoning China Shenyang Aircraft Corporation Shenyang 110034 Liaoning China State Key Laboratory of Roiling and Automation Northeastern University Shenyang 110819 Liaoning China

A stainless steel clad plate composed of stainless steel and carbon steel was prepared by vacuum hot rolling process, and its microstructure, especially the bonding interface, was evaluated using an optical microscope, a scanning electron micro- scope and a transmission electron microscope （TEM）. The corresponding mechanical properties were also assessed by means of hardness and shear tests. The results showed a bonding interface formed between stainless steel and carbon steel, which was relatively straight in macroscope but serrated in microscope. Decarburization layer and carbon-enriched layer were distinguished at the side of carbon steel and stainless steel near the interface, respectively, which should be related to diffusion of carbon and alloying elements. The carbon-enriched layer could also be identified as a recombination region, whose microstructure was mainly recognized as martensite by TEM. Consequently, the hardness was the highest at this region. Furthermore, the result of shear test at the bonding interface showed that the shear strength was 395 MPa and the fracture mode was dominated as ductile fracture, indicating the bonding interface with good quality.

关键词： Stainless steel clad plate Vacuum hot rolling Interface microstructure Mechanical property

Applications of Isolated-Check Visual Evoked Potential in Early Stage of Open-Angle Glaucoma Patients

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Chinese Medical Journal 2018年第20期131卷 2439-2446页

作者： Xiang Fan Ling-Ling Wu Xia Di Tong ding Ai-hua ding Department of Ophthalmology Peking University Third Hospital Beijing 100191 China Beijing Key Laboratory of Restoration of Damaged Ocular Nerve Peking University Third Hospital Beijing 100191 China Department of Ophthalmology Qingdao Sanatorium of Shandong Province Qingdao Shandong 266071 China

Background： Standard automated perimetry does not sufficiently detect early open-angle glaucoma （OAG） in the clinic. New visual function tests for early glaucoma damage are therefore needed. The present study evaluated whether an isolated-check visual evoked potential （icVEP） could be used to detect visual function abnormalities in early-stage OAG and to explore potential related factors. Methods： This was a cross-sectional study. Thirty-seven OAG patients with early-stage visual field loss （mean deviation ≥ -6.00 dB） detected by the Humphrey Field Analyzer （30-2 SITA program） and 26 controls were included in this study. Optical coherence tomography （OCT） was used to detect retinal nerve fiber layer （RNFL） defects. The icVEP preferentially evaluates the magnocellular-ON pathway. VEPs were recorded and signal-to-noise ratios （SNRs） were derived based on multivariate analysis. Eyes that yielded an SNR ≤1 were considered abnormal. Receiver operating characteristic （ROC） curve analysis was used to estimate the accuracy of group classification. Correlations between SNRs and related factors were analyzed. Results： Based on an SNR criterion of 1, the icVEP had a sensitivity of 62.2% and a specificity of 92.3% for diagnosing early-stage OAG with 74.6% classification accuracy. The ROC curve analysis, however, suggested that an SNR criterion of 0.93 would produce the highest classification accuracy （77.3%）. Both RNFL thinning in the temporal superior quadrant on OCT and number of abnormal test points in the central 11° visual field （pattern deviation, P 〈 0.5%） significantly correlated with the SNR （P 〈 0.05）. Conclusions： The icVEP detected visual function abnormalities in approximately 3/5 of eyes with early-stage OAG with greater than 90% specificity. SNR correlated with both a decrease in RNFL thickness and severity of central visual field loss.

关键词： Cross-Sectional Study Isolated-Check Open-Angle Glaucoma Signal-To-Noise Ratios Visual Evoked Potential

Uncertainty assessment of potential evapotranspiration in arid areas, as estimated by the Penman-Monteith method

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Journal of Arid Land 2020年第1期12卷 166-180页

作者： hua ding HAO Xingming ZHANG Ying QIN Jingxiu State Key Laboratory of Desert and Oasis Ecology Xinjiang Institute of Ecology and GeographyChinese Academy of SciencesUrumqi 830011China University of Chinese Academy of Sciences Beijing 100049China

The Penman-Monteith(PM)method is the most widely used technique to estimate potential worldwide ***,current research shows that there may be significant errors in the application of this method in arid areas,although questions remain as to the degree of this estimation error and how different surface conditions may affect the estimation *** address these issues,we evaluated the uncertainty of the PM method under different underlying conditions in an arid area of Northwest China by analyzing data from 84 meteorological stations and various Moderate Resolution Imaging Spectroradiometer(MODIS)products,including land surface temperature and surface ***,we found that when the PM method used air temperature to calculate the slope of the saturation vapor pressure curve,it significantly overestimated the potential evapotranspiration;the mean annual and July–August overestimation was 83.9 and 36.7 mm,***,the PM method usually set the surface albedo to a fixed value,which led to the potential evapotranspiration being underestimated;the mean annual underestimation was 27.5 mm,while the overestimation for July to August was 5.3 ***,the PM method significantly overestimated the potential evapotranspiration in the arid *** difference in estimation was closely related to the underlying surface *** the entire arid zone,the PM method overestimated the potential evapotranspiration by 33.7 mm per year,with an overestimation of 29.0 mm from July to *** most significant overestimation was evident in the mountainous and plain nonvegetation areas,in which the annual mean overestimation reached 5%and 10%,respectively;during July,there was an estimation of 10%and 20%,*** the annual evapotranspiration of the plains with better vegetation coverage was slightly underestimated,overestimation still occurred in July and August,with a mean overestimation of approximately 5%.In order to estimate pote

关键词： Penman-Monteith parameter correction surface temperature albedo Northwest China

Effect of Baking Process on Microstructures and Mechanical Properties of Low Silicon TRIP Steel Sheet With Niobium

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Journal of Iron and Steel Research International 2010年第7期17卷 68-74页

作者： TANG Zheng-you ding hua ding Hao CAI Ming-hui DULin-xiu College of Materials and Metallurgy Northeastern University Shenyang 110004 Liaoning China State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110004 Liaoning China

After 2% predeformation,the baking treatment with different schedule was carried out for low silicon TRIP steel sheet with *** effects of baking temperature and time on microstructures and mechanical properties were *** results showed that with increasing the baking temperature and time,the volume fraction of retained austenite decreases,and the volume fraction of tempered martensite increases; as baking temperature ranges from 80 ℃ to 170 ℃,the bake-hardening（BH）value increases obviously,while from 170 ℃ to 230 ℃,the variation of BH value is very slight; as baking time ranges from 2 min to 20 min,the BH value increases significantly,while the BH value decreases when baking time exceeds 20 *** that when the baking temperature is 170 ℃ and the baking time is 20 min,the low silicon TRIP steel sheet exhibits good bake-hardening behavior,and the highest BH value is above 70 MPa.

关键词： TRIP steel sheet baking process microstructure mechanical property bake-hardening

Integrable Variable-coefficient Coupled Cylindrical NLS Equations and Their Explicit Solutions

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Acta Mathematicae Applicatae Sinica 2014年第4期30卷 1017-1024页

作者： Ting SU Guo-hua ding Jian-yin FANG Department of Mathematical and Physical Science Henan Institute of Engineering

Based on the generalized dressing method, we propose integrable variable coefficient coupled cylin-drical nonlinear SchrSdinger equations and their Lax pairs. As applications, their explicit solutions and their reduct... 详细信息

关键词： variable-coefficient coupled NLS equations the generalized dressing method integrability

Temperature Profile of Black Hole Accretion Disc with Magnetic Coupling

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Communications in Theoretical Physics 2002年第8期38卷 247-252页

作者： LEI Wei-hua WANG ding-Xiong XIAO Kan Department of Physics Huazhong University of Science and Technology Wuhan 430074 China Department of Physics Huazhong University of Science and Technology Wuhan 430074 China Department of Physics Huazhong University of Science and Technology Wuhan 430074 China

Two new mapping relations between the angular coordinate on the black hole (BH) horizon and radialcoordinate on the disc are given according to the requirement of general relativity and Maxwell's equations, and theeffects of magnetic coupling (MC) on temperature of accretion disc are investigated by comparing with pure *** is shown that the MC effects on the temperature profile are related intimately to the BH spin, and the influenceon the peak value of disc temperature based on the modified mapping relations is not as great as that based on thelinear *** peak value and the corresponding radius of peak value ring of disc temperature do not increasemonotonically as the increasing spin of BH, each containing a maximum for the fast-spinning BH. The value ranges ofthe bolometric luminosity and color temperature of the disc are both extended by the MC effects.

关键词： black hole, accretion disc, magnetic coupling

Influences of Thermal Martensites and Grain Orientations on Strain-induced Martensites in High Manganese TRIP/TWIP Steels

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Journal of Materials Science & Technology 2011年第3期27卷 257-265页

作者： Fayun Lu Ping Yang Li Meng Fenge Cui hua ding School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China College of Materials and Metallurgy Northeastern University Shenyang 110004 China

Strain-induced martensites in high manganese TRIP/TWIP steels were investigated in the presence of thermal martensites and under the influence of austenitic grain orientation by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and electron backscattered diffraction （EBSD）. Before deformation, the morphology of α＇- M depended mainly on the number of variants and growing period. Regardless of martensite morphologies and deformation, the Kurdjumov-Sachs （K-S） orientation relationships always maintained. The 6 α＇-M variants formed from a plate of ε-M were of 3 pairs of twins with a common axis 〈110〉α＇ parallel to the normal of {112}γ habit plane to minimize transformation strain. When α＇-M could be formed only by deformation, it nucleated at the intersection of ε-M variants and grew mainly in thick ε-M plates. Thick ε plates promoted significantly the α＇-M and weakened the influence of grain orientations. During tension, the transformation in 〈100〉-oriented grains was observed to be slower than that in 〈121〉-oriented grains. Deformation twins promoted ε-M formation slightly and had no apparent effect on α＇-M. Deformation increased the number of ε-M variants, but reduced that of α＇-M variants.

关键词： High manganese steel Martensite TRIP effect Orientation relationship Electron backscattered diffraction (EBSD)