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Xu H.,North University of China | Wu Z.,Thermal Power Research Institute | Wang X.,Beijing University of Posts and Telecommunications | Zhang X.,Thermal Power Research Institute | And 6 more authors.
Journal Wuhan University of Technology, Materials Science Edition | Year: 2016

Corrosion of Mg–Y alloy was studied using electrochemical evaluations, immersion tests and SEM observations. Corrosion mechanisms of Mg-(0.25 and 2.5) Y alloy and Mg-(5, 8, and 15) Y alloy were uniform corrosion and pitting corrosion respectively, and the content of Mg24Y5 phases determined its effect acting as cathode to accelerate the corrosion or corrosion barrier to inhibit the corrosion. Corrosion resistance of Mg-(0.25, 2.5, 5, 8, and 15) Y alloys was as follows: Rt(Mg-0.25Y) < Rt(Mg-8Y) < Rt(Mg-15Y) < Rt(Mg-5Y) < Rt(Mg-2.5Y). Y could significantly improve the corrosion resistance of the Mg-Y alloy, but the excess of Y deteriorated the corrosion resistance of the Mg-Y alloy. The optimum content of Y in the studied alloys was 2.5%. © 2016, Wuhan University of Technology and Springer-Verlag Berlin Heidelberg.

Liu X.,Beijing University of Technology | Liu X.,Beijing Institute of Technology | Zhang Q.-M.,Beijing Institute of Technology | Wu Q.,Beijing Institute of Technology | Hui R.-J.,Beijing North Vehicle Group Corporation
Binggong Xuebao/Acta Armamentarii | Year: 2013

The conversion ratio between kinetic energy and internal energy is analyzed. The change of surface energy density of first debris cloud with projectile velocity is then analyzed based on dual peak structure in the limit curve, and the possibility of the existence of initiation blind zone when the double-shell casing is shocked by hypervelocity debris is presented in theory. The non-linear dynamics software AUTODYN is used to simulate the shock initiation of composition B charge in double-shell casing impacted by hypervelocity tungsten projectile. The simulation result shows that the blind zone exists. This conclusion is very important to guide the warhead shell structure design and security analysis.

Li M.,Finnish Center for Radiation and Nuclear Safety | Li M.,Beijing North Vehicle Group Corporation | Yang C.,Finnish Center for Radiation and Nuclear Safety | Yan F.,Finnish Center for Radiation and Nuclear Safety | Shi Y.,Beijing North Vehicle Group Corporation
Jixie Qiangdu/Journal of Mechanical Strength | Year: 2013

According to the phenomena of Disk of Prevention Abscission (DPA) which is one of the key parts in heavy vehicle fractured vastly, the reason of fracture failure was analyzed by means of metallographic microscope, direct reading optical spectrometer, rock well hardness tester, microhardness instrument. Experimental results showed that the surface of fracture was planished and coarse. Not only visible plastic deformation could not be found, but also shear lip was not exist on the fracture edge. So the fracture belonged to brittle fracture. The prime factor leads to fracture about DPA is lots of casting shrinkage porosity and impurities exist in DPA, and severe dendritic segregation may increase structural stress. Initial cracks are easy formed in the using process and fracture is caused in the end. In order to avoid fracture again, following principle can be adopted: decreasing impurities during at smelting, avoiding shrinkage porosity during casting, and dendritic segregation of casting must been cancelled by diffusion annealing.

Miao L.,Xinzhou Vocational and Technical College | Zhang X.,Advanced Research Corp. | Zhang X.,General Research Institute for Nonferrous Metals, China | Zhang K.,General Research Institute for Nonferrous Metals, China | And 5 more authors.
Tezhong Zhuzao Ji Youse Hejin/Special Casting and Nonferrous Alloys | Year: 2015

The microstructure and mechanical properties of as-cast Mg-Y alloys with different Y addition were investigated by means of optical microscopy, scanning electron microscopy, X-ray diffractometry and EDS as well as tensile testing. The results reveal that with increase of Y element, the microstructure of the alloy is changed from the single α-Mg phase to the coexist phases of the α-Mg and Mg24Y5. The grain size in the alloy contained Y is refined with the Y content increased from 0.25% to 15%. With the increase of Y element, the tensile strength and hardness of Mg-Y are increased, while the elongation is decreased. ©, 2015, Journal Office of Special Casting and Nonferrous Alloys. All right reserved.

Xu H.,North University of China | Zhang X.,Advanced Research Corp. | Wang C.,Beijing North Vehicle Group Corporation | Liu C.,Beijing North Vehicle Group Corporation | Zhang W.,Beijing North Vehicle Group Corporation
Materials Science Forum | Year: 2016

AZ91D magnesium alloy is one of the most widely used magnesium alloys in the production of metal forming, which use the characteristics from liquid state to solid state of metal to form. The present status of the research and application of the semi-solid forming for AZ91D magnesium alloys at present was reviewed in this paper, including the microstructural characteristics, the thixotropic and rheological behavior, the forming process of semi-solid for AZ91D magnesium alloys and the mechanical properties of the parts made of semi-solid magnesium alloys. The developing prospects and the key points of the semi-solid forming for AZ91D magnesium alloys were forecasted, and the industrial application of the alloy were also discussed. © 2016 Trans Tech Publications, Switzerland.

Xu H.,North University of China | Zhang X.,China Datang Corporation | Liu Y.,China Datang Corporation | Shi Y.,China Military Representative Office of Peoples Liberation Army Stationed in 618 Factory | And 2 more authors.
Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering | Year: 2015

The mechanical properties and the corrosion mechanism of SiCp/2A50 composite materials were studied. The specimens were prepared by the liquid forging. The SiCp particles were added into a partially solidified matrix alloy. The experimental results show that the strength of SiCp/2A50 composite increases with increasing of the SiCp volume fraction, and the ductility of SiCp/2A50 composite decreases with increasing particulates size. The pitting potentials of 2A50 and SiCp/2A50 composite materials are similar. The corrosion resistance of SiCp/2A50 of the pit initiation is almost the same as that of the matrix alloy. It has been found that once pits initiate, the pitting corrosion damage is accelerated owing to the formation of crevices between the reinforcement and the matrix. The cathodic current of the SiCp/2A50 is slightly larger than that of the matrix alloy. The SiCp markedly decreases the pitting corrosion resistance of the composite and the matrix alloy in chloride containing environment. SiCp accelerates the corrosion rate of composite materials, namely the corrosion velocity of composite materials is greater than that of the aluminum alloys. Copyright © 2015, Northwest Institute for Nonferrous Metal Research. Published by Elsevier BV. All rights reserved.

Wu X.,University of Science and Technology Beijing | Guo Z.,University of Science and Technology Beijing | Guo L.,Rensselaer Polytechnic Institute | Yang F.,University of Science and Technology Beijing | And 2 more authors.
Xiyou Jinshu/Chinese Journal of Rare Metals | Year: 2014

NiMo-TiC cermet coating was sprayed by the detonation gun spray system on stainless steel matrix with different oxygen-fuel ratios. The oxygen-fuel ratio in relation to the coating hardness and phase composition and the oxidation behavior of the elements in spraying process were studied. The hardness and the porosity were tested by the coating cross-section metallographic method. The phase composition and the micro-structure were analyzed with X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicated that the hardness of the coating cross-section was about HV0.3 850, and the porosity was closed to 1%. When the oxygen-fuel ratio reached to 1.25:1.00, the hardness decreased. Micro structure of the coating was lamellar and tightly combined with the trans-layer. But there were some unmelted TiC particles with the same dimension of the powder. XRD showed that some TiC particles were converted to TiO and Ti2O3 by oxidation process during the spray. TiO became Ti2O3 when oxygen proportion increased. The relative content of the Ti2O3 increased with the oxygen-fuel ratio increasing. Most of Mo elements were oxidized. The oxydate was gasified by exploded flame. It was found that when the oxygen- ethyne ratio was 1.1:1.0, the gas current in gun's barrel was almost the same as the theoretical detonation wave. The coating performance had preferable overall performance.

Ma X.-G.,Shenyang Ligong University | Zhang R.,Shenyang Ligong University | You X.-M.,Shenyang Ligong University | Ye M.,Beijing North Vehicle Group Corporation | Gong X.-L.,Beijing North Vehicle Group Corporation
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2014

For studying the performance of hydro-pneumatic spring and hydraulic buffer and analyzing their effect on a suspension system, the dynamics model of single-wheel suspension system of a tracked vehicle was established by using the software of RecurDyn. Based on the vehicle dynamics and the crash theory, the cushioning and absorbing characteristics of crash energy of the suspension system were studied. The results show that a dynamics model of single-wheel suspension system used in simulating is valuable for studying the properties of suspension system, which can replace a whole vehicle's simulation to some extent. The hydro-pneumatic suspension system has non-linear and large damping properties and has thus a strong ability to cushion and absorb the crash energy in a large amplitude vibration.

Ma X.-G.,Shenyang Ligong University | Pan S.-W.,Shenyang Ligong University | You X.-M.,Shenyang Ligong University | Ye M.,Beijing North Vehicle Group Corporation | Gong X.-L.,Beijing North Vehicle Group Corporation
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2014

According to the structure of a tracked system in tracked vehicles, the forces acting on components of the tracked system were analyzed and mathematical models for components were established. The formulas for track tensions and normal forces between wheels and ground were derived with the mathematical models, and the formulas were verified by comparing the calculated results with the formulas to the simulation results with Recurdyn dynamci model. The formulas provided a theoretical basis for control of tensions of a tracked system.

Cai J.,Xi'an University of Architecture and Technology | Wang K.,Xi'an University of Architecture and Technology | Han Y.,Beijing North Vehicle Group Corporation
High Temperature Materials and Processes | Year: 2016

True stress and true strain values obtained from isothermal compression tests over a wide temperature range from 1,073 to 1,323 K and a strain rate range from 0.001 to 1 s-1 were employed to establish the constitutive equations based on Johnson Cook, modified Zerilli-Armstrong (ZA) and strain-compensated Arrhenius-type models, respectively, to predict the higherature flow behavior of Ti-6Al-4V alloy in α + β phase. Furthermore, a comparative study has been made on the capability of the three models to represent the elevated temperature flow behavior of Ti-6Al-4V alloy. Suitability of the three models was evaluated by comparing both the correlation coefficient R and the average absolute relative error (AARE). The results showed that the Johnson Cook model is inadequate to provide good description of flow behavior of Ti-6Al-4V alloy in α + β phase domain, while the predicted values of modified ZA model and the strain-compensated Arrhenius-type model could agree well with the experimental values except under some deformation conditions. Meanwhile, the modified ZA model could track the deformation behavior more accurately than other model throughout the entire temperature and strain rate range. © 2016 by De Gruyter.

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