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Tensile ductility and deformation mechanisms of a nanotwinned 316L austenitic stainless steel

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journal of Materials Science & Technology 2020年第1期36卷 65-69页

作者： y.Z.Zhang j.j.Wang n.R.Tao Shenyang national Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China University of Chinese Academy of Sciences Beijing 100049China

A nanotwinned 316 L austenitic stainless steel was prepared by means of surface mechanical grinding *** recovery annealing,the density of dislocations decreases obviously while the average twin/matrix lamella thickness still keeps in the nanometer *** annealed nanotwinned sample exhibits a high tensile yield strength of 771 MPa and a considerate uniform elongation of 8%.TEM observations showed that accommodating more dislocations and secondary twinning inside the nanotwins contribute to the enhanced ductility and work hardening rate of the annealed nanotwinned sample.

关键词： nanotwinned Stainless steel Ductility Deformation mechanism

nUMERICAL AnALySIS OF HEAT TRAnSFER DURInG LASER CLADDInG TO SynTHESIZE TiCp/Al COMPOSITE

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Acta Metallurgica Sinica(English Letters) 2004年第1期17卷 1-6页

作者： D.n.Zou j.yang y.L.Huang j.y.Su School of Metallurgical Engineering Xi'an University of Architecture and Technology Xi'an 710055ChinaSchool of Metallurgical EngineeringXi'an University of Architecture and Technology Xi'an 710055ChinaSchool of Materials Science and Engineering Xi'an Jiaotong University Xi'an 710049 ChinaSchool of Materials Science and Engineering Xi'an Jiaotong University Xi'an 710049 China

Based on the continuum model for binary solid-liquid phase change system, the math-ematic model to simulate the process of laser cladding in situ synthesis TiCp/Al composite on the surface of aluminum alloy was formulated. The additive source method was employed to treat with the heat release of synthetic reaction in powder mixture at certain temperatures, and also to solve the momentum and heat transfer caused by the relative movement between laser beam and the specimen. Two different types of driving forces for flow were considered in the model, i.e., the buoyancy force and the surface tension gradient at the laser pool surface. The three-dimensional transient temperature field simulation program was developed being based upon the commercial software PHOEnICS. The calculated and observed fusion boundaries were compared and very good agreement was obtained.

关键词： numerical simulation heat transfer laser cladding in situ synthesis composite

MODELInG THE KnOWLEDGE CREATIOn PROCESS OF GRADUATE RESEARCH

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journal of Systems Science and Systems Engineering 2018年第6期27卷 790-809页

作者： j. Sun j. Tian V.n. Huynh y. nakamori School of Knowledge Science Japan Advanced lnstitute of Science and Technology lshikawa Japan School of Computer Science and Technology Wuhan University of Technology Wuhan China

Graduate students who are beginning academic research want to learn how to create and verify new knowledge in their research. Their supervisors, on the other hand, are seeking appropriate research environments including effective research guidance methods. In order to meet these demands, this paper proposes a knowledge creation model that supports the objectives of both graduate students and their supervisors. This is an academic knowledge creation model for individuals supported by a group and its origin can be traced back to a famous organizational knowledge creation model. Since this type of model is constructed from empirical knowledge, it is not easy to prove its objective significance. But, this paper tries to show the effectiveness of the proposed model as an initial stage of model validation based on a questionnaire survey of students in a graduate school in China.

关键词： Knowledge creation model graduate students research ability research environment

DETERMInATIOn OF BLAnK HOLDER FORCE In SHEET METAL DEEP DRAWInG PROCESS

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维普期刊数据库

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Acta Metallurgica Sinica(English Letters) 2003年第1期16卷 31-34页

作者： y.j.Luo y.Q.Zhang D.n.He Dept. of Plasticity Technol. Shanghai Jiaotong Univ. Shanghai 200030 China

Blank holder force (BHF) is an important measure to control the sheet metal forming. BHF is identified quickly using artificial neural network (Ann) on the basis of its analytical description. And critical rupture and... 详细信息

关键词： blank holder force sheet metal deep drawing artificial neural network

CO_2 laser-micro plasma arc hybrid welding for galvanized steel sheets

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Transactions of nonferrous Metals Society of China 2011年第A1期21卷 47-53页

作者： C.H.KIM y.n.AHn j.H.KIM Advance Welding & joining Research Group Korea Institute of Industrial Technology Incheon 406-840 South Korea

A laser lap welding process for zinc-coated steel has a well-known unsolved problem-porosity formation. The boiling temperature of coated zinc is lower than the melting temperature of the base metal, which is steel. In the autogenous laser welding, the zinc vapor generates from the lapped surfaces expels the molten pool and the expulsion causes numerous weld defects, such as spatters and blow holes on the weld surface and porosity inside the welds. The laser-arc hybrid welding was suggested as an alternative method for the laser lap welding because the arc can preheat or post-beat the weldment according to the arrangement of the laser beam and the arc. CO2 laser-micro plasma hybrid welding was applied to the lap welding of zinc-coated steel with zero-gap. The relationships among the weld quality and process parameters of the laser-arc arrangement, and the laser-arc interspacing distance and arc current were investigated using a full-factorial experimental design. The effect of laser-arc arrangement is dominant because the leading plasma arc partially melts the upper steel sheets and vaporizes or oxidizes the coated zinc on the lapped surfaces. Compared with the result from the laser-TIG hybrid welding, the heat input from arc can be reduced by 40%.

关键词： galvanized steel CO2 laser micro plasma hybrid welding

CO and Particle Pollution of Indoor Air in Beijing and Its Elemental Analysis

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Biomedical and Environmental Sciences 1990年第2期3卷 132-138页

作者： j.n.WAnG y.ZHAnG Institute of Environmental Health and Engineering Chinese Academy of Preventive Medicine Beijing China

Three representative types of houses in Beijing were selected and, in each type, smoking and nonsmoking households were compared. IP, RP. and CO concentrations in the living room and kitchen were monitored during each season. and the level of COHb in the heads of the households were measured. The study showed that indoor air pollution was rather severe, especially during winter. when paniculate concentrations markedly exceeded the standard and CO concentration was as high as 47 ppm. Indoor air pollution was closely related to the type of house, particularly to the mode of heating. In houses. of the same type, pollution improved greatly after central heating facilities were installed. Analysis of 30 elements revealed that pollution was typically caused by coal burning. aggravated by dusty wind, but high indoor Pb levels were probably due to the use of LPG for cooking. In our study the effect of cigarette smoking was sometimes masked by the severe indoor pollution. (C)1990 Academic Press, Inc.

关键词： Be In CO and Particle Pollution of Indoor Air in Beijing and Its Elemental Analysis COHb

Thermoluminescence glow curve analysis and kinetic parameters of Dy-doped BaSi_(2)O_(5)phosphor

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journal of Rare Earths 2022年第2期40卷 234-242,I0002页

作者： y.Alajlani n.Can Physics Department Jazan UniversityP.O.Box 114Jazan45142Saudi Arabia Department of Physics Faculty of Arts and SciencesManisa Celal Bayar UniversityMuradiye-Manisa45010Turkey

In this paper,Dy^(3+)incorporated BaSi_(2)O_(5)phosphors were synthesized by gel co mbustion method and characterized by X-ray diffraction(XRD).The effects of various heating rate s on thermoluminescence(TL)kinetics and glow peak temperatures of Dy^(3+)incorporated BaSi_(2)O_(5)phosphors exposed toβirradiation at room temperature were *** glow curves of the phosphor exposed toβ-irradiation(0.1-100 Gy)consist of four main peaks located at 87,130,271,and 327℃and exhibit a good linearity between 0.1 and100 *** experimental techniques including variable heating rate(VHR),repeated initial rise(RIR),peak shape(PS)and computerized glow curve deconvolution(CGCD)were employed to determine TL kinetic *** findings indicate that the TL glow peaks of the phosphor obey first-order *** of the main dosimetric peaks through the techniques mentio ned above indicates that activation energies(E)and pre-exponential factor(s)are in the range of 0.80-1.50 eV and 1.15×10^(8)-3.28×10^(13)s^(-1).Additionally,it is found that the temperature of the glow peaks shifts toward the higher temperatures and the TL intensity smoothly decreases as the heating rate *** effect on the TL intensities and glow peak temperatu res of the heating rate is discussed in terms of thermal quenching.

关键词： BaSi_(2)O_(5) Dy^(3+) Gel combustion XRD Thermoluminescence Kinetic parameters

RELATIOnSHIP AMOnG EVAPORATIOn FLUX OF GROUnDWATER, DEPTH OF WATER TABLE AnD nEGATIVE PRESSURE HEAD In BARE SOIL

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journal of Hydrodynamics 2000年第4期12卷 52-58页

作者： Qian, j.Z. Zhu, X.y. Zhou, n.Q. Li, G.y. Dep. of Earth Sci. Nanjing Univ. Nanjing 210093 China

Evaporation of ground water is a part of moisture circulation in the field. And it is a main natural form in which water transmits from the ground water to the soil water and atmosphere water. According to the simulated experiments, we study the relationship among the evaporation, depth of groundwater table and negative pressure. By theoretical analysis of the experimental results, the main conclusions are drawn as follows. There are two abrupt points in every Q-H curve. The locations of the abrupt points are separately in step with the height of top of the capillary fringe and the height of maximal capillary rise in the soil section. When the depth of water table H is small, the evaporation flux of ground water is large. While the depth of water table exceeds the maximal capillary rise of media in vadose zone, the capillary rise breaks up and evaporation flux of groundwater is small. The water content ratio in ground surface tends to be zero and the surface of soil tends to be drought. These conclusions show that the maximal capillary rise of media in vadose zone is an important value in regulating rational depth of ground water to reduce the evaporation of ground water and to increase effective quantity of water resources. In the meantime, these conclusions are of important theoretical and practical significance to reduce the evaporation of ground water, to prevent and cure the salinization of soil, and to make full use of and protect water resources in the northern plains in China.

关键词： Capillarity Evaporation Soils

Atomic-scale roles of Zn element in age-hardened AlMgSiZn alloys

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journal of Materials Science & Technology 2021年第11期70卷 105-112页

作者： n.n.jiao y.X.Lai S.L.Chen P.Gao j.H.Chen Center for High-Resolution Electron Microscopy College of Materials Science&EngineeringHunan UniversityChangsha410082China Electron Microscopy Laboratory and International Center for Quantum Materials School of PhysicsPeking UniversityBeijing100871China

Adding alloying elements to improve the performances or the manufacturing processes of Al-Mg-Si alloys has long been a serious issue in developing advanced automotive aluminum *** Zn element,among those promising ones,has demonstrated positive alloying effects on Al-Mg-Si ***,the atomic-scale roles of Zn in an age-hardened Al-Mg-Si-Zn alloy have not been adequately *** atomic-resolution electron microscopy,here we report the precise locations of Zn elements in all hardening precipitates involved and their alloying mechanism at the atomic scale when alloying the *** results show that Zn atoms enter all the major hardening phases to occupy specific featured atomic sites of the original elements,*** Si1 and Mg2 sites in theβ’-2 phase,and modify their crystal structures,interfacial structures and morphologies in characteristic *** is revealed that for theβ’-phase,Zn atoms occupy unique atomic sites,whereas for other phases,they demonstrate similar behaviors as other additive alloying elements such as Ag and Cu do.

关键词： Al-Mg-Si alloy Zn addition Precipitate Electron microscopy