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PREDICTION OF FLOW STRESS OF hIGh-SPEED STEEL DURING hOT DEFORMATION bY USING bP ARTIFICIAL NEURAL NETWORK

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Acta Metallurgica Sinica(English Letters) 2000年第1期13卷 394-400页

作者： J. T. Liu h.b. chang R.h. Wu T. Y. hsu(Xu Zuyao) and X.R. Ruan( 1)Department of Plasticity Technology, Shanghai Jiao Tong University, Shanghai 200030, China 2)School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200030,

The hot deformation behavior of TI (18W-4Cr-1V) high-speed steel was investigated by means of continuous compression tests performed on Gleeble 1500 thermomechan- ical simulator in a wide range of tempemtures (950℃-1150℃) with strain rotes of 0.001s-1-10s-1 and true strains of 0-0. 7. The flow stress at the above hot defor- mation conditions is predicted by using bP artificial neural network. The architecture of network includes there are three input parameters:strain rate,temperature T and true strain , and just one output parameter, the flow stress ,2 hidden layers are adopted, the first hidden layer includes 9 neurons and second 10 negroes. It has been verified that bP artificial neural network with 3-9-10-1 architecture can predict flow stress of high-speed steel during hot deformation very well. Compared with the prediction method of flow stress by using Zaped-holloman parumeter and hyperbolic sine stress function, the prediction method by using bP artificial neurul network has higher efficiency and accuracy.

关键词： T1 high-speed steel flow stress prediction of flow stress back propagation (bP) artificial neural network (ANN)

Assessment of deterioration in RhA-concrete due to magnesium sulphate attack

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International Journal of Minerals,Metallurgy and Materials 2010年第6期17卷 691-696页

作者： G.A. h.b.eb h.b. Mahmud N.b.A.A. hamid Department of Civil Engineering Faculty of Engineering University of Malaya

The assessment of magnesium sulphate attack on concretes containing rice husk ash （RhA, 20wt% of the cementitious materials） with various average particle sizes was investigated. The total cementitious materials were 390 kg and the water-to-binder ratio （W/b） was 0.53 for all mixtures. Specimens were initially cured in water for 7 d and then immersed in the 3wt% magnesium sulphate solution for up to 111 d of exposure. The specimens were subjected to drying-wetting cycles to accelerate sulphate attack. In addition to the visual monitoring of the specimens, the concrete specimens were subsequently tested for compressive strength, dynamic modulus of elasticity, and length and mass changes. The results show that the specimens exposed to sulphate attack exh.b.t higher strength and dynamic modulus than those kept in water. The length change is negligible and can be attributed to the normal swelling of concrete. On the other hand, concretes suffers mass loss and surface spalling and softening; the fine RhA-concrete results in a better resistance. For the accelerated sulphate attack method used in this study, mass change and visual monitoring are recommended for assessing the deterioration degree and the effectiveness of supplementary cementitious materials to resist sulphate attack.

关键词： concretes pozzolan ettringite rice husk ash (RhA) magnesium sulphate

EXPERIMENTAL AND ThEORETICAL INVESTIGATION OF PSEUDOELASTIC hYSTERESIS IN ShAPE MEMORY ALLOYS

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Acta Metallurgica Sinica(English Letters) 1999年第3期12卷 235-240页

作者： Gong, S.K. Xu, h.b. beijing Univ of Aeronautics and Astronautics Beijing China

The pseudoelastic hysteresis loop associated with phase equilibrium and the stress relaxation on the yield line were investigated, and the theoretical description was confirmed by deformation controlled load-deformation measurements on CuZnAl single crystals. It was found that in a loading-unloading process, the states of shape memory alloys run through a hysteresis loop, and the points that trigger the internal yield and recovery inside the pseudoelastic hysteresis loop define a line that traverses the hysteresis loop from the upper left to the lower right corner. This line was interpreted as a line of unstable phase equilibrium according to the thermodynamic arguments, which determines also the tendency for stress relaxation on the yield line section and for a stress growth on the recovery line section.

关键词： Aluminum copper alloys hysteresis Stress relaxation

IMPROVED COhESIVE ZONE MODEL AND ITS APPLICATION IN INTERFACE CONTACT ANALYSIS

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Acta Metallurgica Sinica(English Letters) 2008年第4期21卷 295-302页

作者： Y. Wang J. Chen h.b. Li National Die ＆ Mold CAD Engineering Research Center Shanghai Jiaotong University Shanghai 200030China

An improved interface cohesive zone model is developed for the simulation of interface contact, under mixed-mode loading. A new debonding initiation criterion and propagation of debonding law, taking into account the pressure stress influence on contact shear strength, is proposed. The model is implemented in a finite-element program using subroutine VUINTER of AbAQUS Explicit. An edge-notch four-point bending process and laminated vibration damping steel sheet punch forming test are simulated with the improved model in AbAQUS Explicit. The numerical predictions agree satisfactorily with the corresponding experimental results.

关键词： Cohesive zone model Mixed mode Damage criterion Contact stress

MICROSTRUCTURE AND MEChANICAL PROPERTIES OF Mg-Li ALLOY WITh Ca ADDITION

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Acta Metallurgica Sinica(English Letters) 2006年第5期19卷 355-361页

作者： h.b. Li G. C. Yao Z.Q. Guo Y.h. Liu h.J. Yu h.b. Ji School of Materials ＆ Metallurgy Northeastern University Shenyang 110004 China

Mg-9wt%Li-2wt%Zn alloy was prepared and studied in this article. The addition of Ca to the alloy from 0.1wt% to 1wt% can refine the α-Mg and the best effect of refinement occurs when Ca content is 0.4wt%-0.5wt%. The billets can be rolled to thin sheets at room temperature, from which it is obvious that the addition of Ca improves alloys ormalin. while it decreases with the excess addition of Ca. The results also show that the ultimate tensile strength （UTS） and yield strength （YS） of the alloy with lwt% Ca may rise by 28% and 25%, respectively, however, the elongation decreases. It is clarified that the adsorption of proper Ca on the grain boundaries refines α-Mg and improves the tensile properties, but the presence of excess Ca and stable Ca2Mg6Zn3phase worsens the elongation.

关键词： calcium Mg-Li-Zn alloy cold rolling microstructure tensile property

Current Status in Layered Ternary Carbide Ti_3SiC_2,a Review

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Journal of Materials Science & Technology 2009年第1期25卷 1-38页

作者： h.b. Zhang Y.W. bao Y. C. Zhou Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

This article provides a review of current research activities that concentrate on Ti3SiC2. We begin with an overview of the crystal and electronic structures, which are the basis to understand this material. Followings are the synthetic strategies that have been exploited to achieve, and the formation mechanism of Ti3SiC2. Then we devote much attentions to the mechanical properties and oxidation/hot corrosion behaviors of Ti3SiC2 as well as some advances achieved recently. At the end of this paper, we elaborate on some new discoveries in the Ti3SiC2 system, and also give a brief discussion focused on the ＂microstructure -property＂ relationship.

关键词： Layered ternary ceramics Ti3SiC2 Mechanical properties Oxidation

Efficient and simple synthesis of b_(2)O_(3)-Al_(2)O_(3)nanocomposites assisted by deep eutectic solvent for production of 5-hydroxymethylfurfural from glucose

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Nano Research 2025年第1期18卷 236-248页

作者： Yuchen Wang Kai Rong Shanlei chang Youxing Fang Shaojun Dong State Key Laboratory of Electroanalytical Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China School of Applied Chemistry and Engineering University of Science and Technology of ChinaHefei 230026China College of Chemistry Jilin UniversityChangchun 130012China

The catalytic conversion of glucose to high valueadded platform chemical 5-hydroxymethylfurfural(hMF)is a promising biorefinery process,and alumina-boria catalysts are considered to be green and mild solid acid catalysts for this catalytic ***,compared to the common synthesis methods with complicated steps,we reported a simple and efficient strategy to prepare b_(2)O_(3)-Al_(2)O_(3)nanocomposites by calcining cost-effective glucose-urea deep eutectic solvent(DES)solution containing the *** prepared b_(2)O_(3)-Al_(2)O_(3)nanocomposites exh.b.ted an open three-dimensional skeleton and two-dimensional porous lamellar substructure,endowing them with a high specific surface area(228.27 m2/g).The introduction of boron changed the ratios of different aluminum species(AlⅣ,AlⅤ,and AlⅥ)and borate species(bO3 and bO4),thus further affecting the acidity and the types of acid sites of the *** prepared b_(2)O_(3)-Al_(2)O_(3)bifunctional acid catalysts possessing abundant Lewis acid sites and adjustable brønsted acid sites showed complete glucose conversion and 55.38%of hMF yield under the optimum *** study proposed a concise method to synthesize alumina-boria solid acid catalysts assisted by glucose-urea *** hope to extend the application and prospect of this efficient and simple synthesis strategy.

关键词： 5-hydroxymethylfurfural(hMF) deep eutectic solvent glucose alumina-boria acid catalyst

FEM ANALYSIS OF ThERMAL STRESSES IN GRADIENT ThERMAL bARRIER COATINGS PRODUCED bY Eb-PVD

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Acta Metallurgica Sinica(English Letters) 2001年第6期14卷 493-496页

作者： h.b. Guo, h.b. Xu and S.K. Gong (Department of Materials Science & Engineering, beijing University of Aeronautics and Astronautics, beijing 100083, China) Dept. of Mat. Sci. and Eng. Beijing Univ. of Aero. and Astron. Beijing 100083 China

Gradient thermal barrier coatings (GTbCs) produced by co-deposition of mixtures ofAl-Al2 O3-YSZ onto metallic bond coat exh.b.ted longer lifetimes than the two-layeredTbCs. The finite element method (FEM) numerical models were used to investigatestress and strain states in the GTbCs and traditional two-layered TbCs as they cooledto 750℃ from a stress-free state at 850℃.

关键词： Eb-PVD gradient thermal barrier coating finite element method

COMPOSITION TRIANGLE DIAGRAMS OF Ni-Mn-Ga MAGNETIC ShAPE MEMORY ALLOYS

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Acta Metallurgica Sinica(English Letters) 2006年第3期19卷 171-175页

作者： Y.F. Wang J.M. Wang C.b. Jiang h.b. Xu School of Materials Science and Engineering Beijing University of Aeronautics and Astronautics Beijing 100083 China

A statistical work has been done to collect the composition ranges of Ni-Mn-Ga alloys exh.b.ting different structures and martensite start temperature （M,）, large magnetostrain or the co-existence of magnetic and structural transitions. The alloys with five-layered （5M）, seven-layered （7M） modulated and non-modulated （T） martensitic structures were mapped in the graph. An empirical formula has been presented to reflect the effect of elements nickel （Ni ）, manganese （ Mn ） and gallium （Ga）, on the martensite start temperature （M3）. The martensitic structure is sensitive to the composition and the martensitic transformation temperature is most drastically affected by the Ni content. The alloys with large magnetostrain or co-existence effect of the magnetic and structural transitions were also listed in a limited area.

关键词： Ni2MnGa alloy martensitic transformation magnetic shape memory alloy