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Influence of Inclusion on Crack Initiation in Wheel Rim

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Journal of Iron and Steel Research International 2011年第1期18卷 49-54页

作者： mi guo fa NAN Hong yan LIU Yan-lei ZHANG Bin ZHANG Hong SONG guo xiang School of Materials Science and Engineering Henan Polytechnic University Jiaozuo 454003 Henan China Datong ABC Casting Co Ltd Technology and Quality Department Datong 037038 Shanxi China Metals and Chemistry Institute China Academy of Railway Sciences Beijing 100081 China

Speed increase and heavy haul of the railway freight car are the effective measures to raise the transport ability of railway, and they have been the new trend for railway freight car development. The increase of speed and axle load will lead to the increase of wheel rail contact stress, which will make a great change of stress distribution in the whole wheel rim. Goodier equation was employed to analyze the stress state around inclusion and cavity. In the operation of wheel-rail contact stress, stress concentration occurred in the pole of Al2O3 spherical inclusion, while it appeared on the equator of cavity. The critical inclusion sizes of 250 kN axle load freight car wheel at different velocities, a certain distance away from the tread, were calculated by Murakami equation. Comparing the inclusion in cast steel wheel with that in rolled steel wheel, it is found that the inclusion in cast steel wheel has much more excellent crack resistance than that in rolled steel wheel. In the meantime, in order to reduce the probability of rim crack, some suggestions were put forward.

关键词： heavy haul contact stress critical inclusion size rim crack

Modeling of Cell/Dendrite Transition During Directional Solidification of Ti-Al Alloy Using Cellular Automaton Method

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Journal of Iron and Steel Research International 2008年第3期15卷 82-86页

作者： WANG Kuang-fei LI Bang-sheng mi guo-fa guo Jing-jie FU Heng-zhi School of Materials Science and Engineering Henan Polytechnic University Jiaozuo 454100 Henan China School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 Heilongjiang China

Solute diffusion controlled solidification model was used to simulate the initial stage cellular to dendrite transition of Ti44Al alloys during directional solidification at different velocities. The simulation results show that during this process, a mixed structure composed of cells and dendrites was observed, where secondary dendrites are absent at facing surface with parallel closely spaced dendrites, which agrees with the previous experimental observation. The dendrite spacings are larger than cellular spacings at a given rate, and the columnar grain spacing sharply increases to a maximum as solidification advance to coexistence zone. In addition, simulation also revealed that decreasing the numbers of the seed causes the trend of unstable dendrite transition to increase. Finally, the main influence factors affecting cell/dendrite transition were analyzed, which could be the change of growth rates resulting in slight fluctuations of liquid composition occurred at growth front. The simulation results are in reasonable agreement with the results of previous theoretical models and experimental observation at low cooling rates.

关键词： Ti44Al alloy cell/dendrite transition directional solidification solute diffusion controlled model cell/ dendrite spacing

Preparation,Structure and Mechanical Properties of Nickel Based Porous Spherical Superalloy

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Journal of Iron and Steel Research International 2009年第1期16卷 92-96页

作者： mi guo fa LI Hong-yu LIU Xiang-yu WANG Kuang-fei School of Materials Science and Engineering Henan Polytechnic University Jiaozuo 454000 Henan China School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 Heilongjiang China

The porous superalloy materials with hollow spherical pores were fabricated by using metal powder sintering process. The scanning electron microscope （SEM） observation was applied to the test samples and it revealed that the pores of the porous material exhibited a uniform distribution and the apertures were of same size in principle. The sintering necks appeared between adjacent particles on metal skeleton after sintering. The mechanical properties of the test samples were analyzed and the result showed that this kind of materials possessed excellent energy absorption capability, and the compression resistance decreased with increasing the porosity and aperture.

关键词： porous superalloy material metal powder sintering hollow spherical pore oriented linear pore

Wear Property of Cast Steel Wheel Material in Rail Truck

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Journal of Iron and Steel Research International 2009年第3期16卷 73-77页

作者： mi guo-fa LIU Yan-lei ZHANG Bin FU Xiu-qin ZHANG Hong SONG guo-xiang School of Materials Science and Engineering Henan Polytechnic University Jiaozuo 454003 Henan China Metals and Chemistry Institute China Academy of Railway Sciences Beijing 100081 China Datong ABC Casting Co Ltd Datong 037038 Shanxi China

Wear property of material plays a key role in the service time of workpiece. A major objective in the development of new wheel materials is to improve the wear performance. The wear property of B and B＋ grade cast steel materials was reported. The results showed that B＋ grade cast steel material exhibited better wear property than the B grade material. Carbon content related to the hardness match was the principal factor affecting the wear properties.

关键词： wear property wheel hardness carbon content

Effects of diamond particle size on microstructure and properties of diamond/Al-12Si composites prepared by vacuum-assisted pressure infiltration

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China Foundry 2024年第4期21卷 360-368页

作者： Jia-ping Fu Can-xu Zhou guo-fa mi Yuan Liu School of Materials Science and Engineering Henan Polytechnic UniversityJiaozuo 454100HenanChina School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China Key Laboratory for Advanced Materials Processing Technology Ministry of EducationBeijing 100084China

Diamond/aluminium composites have attracted attention in the field of thermal management of electronic packaging for their excellent *** order to solve the interfacial problem between diamond and aluminium,a novel process combining pressure infiltration with vacuum-assisted technology was proposed to prepare diamond/aluminum *** effect of diamond particle size on the microstructure and properties of the diamond/Al-12Si composites was *** results show that the diamond/Al-12Si composites exhibit high relative density and a uniform *** thermal conductivity and coefficient of thermal expansion increase with increasing particle size,while the bending strength exhibits the opposite *** the average diamond particle size increases from 45μm to 425μm,the thermal conductivity of the composites increases from 455 W·m^(-1)·K^(-1)to 713 W·m^(-1)·K^(-1)and the coefficient of thermal expansion increases from 4.97×10^(-6)K^(-1)to 6.72×10^(-6)K^(-1),while the bending strength decreases from 353 MPa to 246 *** research demonstrates that high-quality composites can be prepared by the vacuum-assisted pressure infiltration process and the thermal conductivity of the composites can be effectively improved by increasing the diamond particle size.

关键词： diamond/aluminum composites thermal conductivity electronic packaging vacuum-assisted pressure infiltration

Tensile properties and fracture characteristics of spray cast alloy IC6 (Ni-7.8Al-14Mo-0.05B)

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China Foundry 2007年第1期4卷 10-12页

作者： mi guo-fa WANG Hong-wei TIAN Shi-fan LI Zhou ZENG Song-yan Henan Polytechnic Institute Jiaozuo 454000 China Harbin Institute of Technology Harbin 150001 China Institute of Aeronautical Materials Beijing 100095 China

Tensile testing results of spray cast Ni3Al-based superalloy indicated that the yield strength and tensile strength increase with the increasing of temperature and reached maximum at around 760℃, then decrease with the increasing of temperature. After high temperature isostatic pressing (HIP), yield strength decreased and ductility and tensile strength increased. Stereographic projection showed that no matter at room temperature, medium temperature or high temperature, cracks extend along (111).

关键词： spray casting Ni3Al-based superalloy tensile properties fracture characteristics

Structural and Thermodynamic Properties of TiAl intermetallics under High Pressure

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Communications in Theoretical Physics 2012年第1期57卷 141-144页

作者： LI Xu-Sheng WANG Hai-Yan LI Chang-Yun mi guo-fa HU Qian-Ku School of Materials Science and Engineering Henan Polytechnic UniversityJiaozuo 454000China

The structural and thermodynamic properties of TiAI intermetallics under high pressure have been investigated by ab initio plane-wave pseudopotential density functional theory method. It is found that the ratio of lattice parameter c to a keeps almost constant with a value of 1.02 under the pressure from 0 to 20 GPa, which agrees well with the experimental results. With the pressure increasing from 20 to 45 GPa the values of c/a decrease almost linearly from 1.02 to 0.99. These calculated results indicate under low pressure the variation rate for a-axis is almost the same to that for c-axis, but under higher pressure the variation for a-axis is smaller than along e-axis. Through the quasi-harmonic Debye model, the equation of state （EOS） of TiAI intermetallies, as well as the thermal expansion and heat capacity at various pressures and temperatures are also studied.

关键词： density functional theory thermodynamic properties TiAl

On grain refinement and titanium segregation in Al-Si alloy

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China Foundry 2007年第4期4卷 273-275页

作者： mi guo-fa WANG Kuang-fei WEN Tao ZHANG ming WANG Hong-wei ZENG Song-yan School of Materials Science and Engineering Henan Polytechnic University Jiaozuo 454000 China School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China

The influence of holding time and distance from sample bottom on segregation and grain refinement of Ti was studied. Results show that Al-STi-IB has an obvious effect on refinement in AI-Si alloy after 4 h holding time. The segregation of Ti shows different morphology at different positions of casting. More segregation is at the bottom of castings because of localized congregation of Ti. The research shows that the difference in Ti concentration is as high as 25.6% between the top and bottom of castings.

关键词： aluminum-silicon alloy Ti segregation grain refinement

Highly crystallization-induced emissive luminophores with mechanoluminescent features for two-photon harvesting fluorescence imaging and latent fingerprint identification

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Nano Research 2024年第7期17卷 6475-6482页

作者： Jian Lu Juan Gao Rui-Xuan Qian Shuai-Hua Wang fa-Kun Zheng guo-Cong guo Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of China Fuzhou 350108China State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China

Fluorescence imaging can be employed in fields of medical treatment,astronomical exploration,and national defense *** fluorescence imaging often takes the single-photon techniques,which is vulnerable to background interference and ***,two-photon fluorescence imaging can achieve much higher-resolution fluorescence imaging for reducing scattering and deeper ***,by assembling the tetraphenylethylene backbones with nontoxic and non-noble K^(+)ions,compound 1([(Hdma)K(H_(2)ettc)]_(n),H_(4)ettc=4',4''',4''''',4'''''''-(ethene-1,1,2,2-tetrayl)tetrakis(([1,1'-biphenyl]-4-carboxylic acid)))with the crystallization-induced emissions exhibited charming fluorescence imaging under two-photon excitation microscopy(TPEM).Besides,luminescent powders based on compound 1 can achieve high-resolution fingerprint recognition,providing secure access control and identification for a novel authentication *** with the commercial fluorescent dyes coumarin-6,the as-synthesized compound 1 showed great solvent stability,indicating its durability against harsh ***,compound 1 shows mechanoluminescent properties for the perturbation of weak supramolecular interactions within ordered arrangements of the H_(2)ettc^(2−)*** novel compound has provided an important insight to the development of twophoton fluorescence imaging and advanced external-stimuli responsive materials.

关键词： crystallization-induced emission fluorescence imaging two-photon absorption fingerprint recognition mechanoluminescence