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Li Z.-W.,Beijing Hangxing Technology Development Company Ltd | Liu X.-C.,Beijing Hangxing Technology Development Company Ltd | Bian Y.,Beijing Hangxing Technology Development Company Ltd | Zhou N.,Csic No12 Research Institute
Zhuzao/Foundry | Year: 2014

By using of the low pressure casting process, A357 cylinder castings were cast and the effects of different solidification conditions on the microstructure and mechanical properties of cylinder casting were studied. When sand mold cooling wall thickness is 20 mm, the average value of secondary dendrite arm spacing is 40% more than the part where the thickness is 10 mm. At the part where the wall thickness is 20 mm cooling with chill, the secondary dendrite arm spacing is 40% less than the same thickness part cooling with sand mold. And the secondary dendrite arm spacing is the same as with that of wall thickness 10 mm cooling with sand mold. The mechanical properties of casting cooling with chill were significantly increased. Relative to the thin wall casting part, thick wall casting part cooling with chill the mechanical properties increased more dramatically. Also, the solidification conditions have impact on the fracture mechanism of thick wall casting part. For the castings of wall thickness 20 mm, the fracture type of casting with sand mold cooling has the transgranular fracture trend and the fracture type of casting with chill cooling has the intergranular fracture trend.


Zhang Y.-P.,Northwestern Polytechnical University | Zhang Y.-P.,Beijing Hangxing Technology Development Co. | Lin X.,Northwestern Polytechnical University | Wei L.,Northwestern Polytechnical University | And 3 more authors.
Wuli Xuebao/Acta Physica Sinica | Year: 2013

The dendritic growth patterns in directional solidification with different amplitudes of solid-liquid interface energy anisotropy were investigated using the two-dimensional cellular automata (CA) model. It is shown that when the preferred growth direction of the crystal was the same as the direction of thermal gradient, the solidification pattern would transform from seaweed to dendrite with the increase of amplitude of interface energy anisotropy. The amplitude of interface energy anisotropy could also influence the morphology of dendritic tips. As the amplitude of interface energy anisotropy increased, the dendritic tip radius, the liquid concentration ahead of the tip and the tip undercooling decreased. A power law relationship evisted between the stability parameter of dendritic tip and the amplitude of interface energy anisotropy in directional solidification. The primary arm spacing changed little with the increase of interface energy anisotropy. When the angle between the preferred growth direction of the crystals and the direction of thermal gradient was -40°, and the amplitude of interface energy anisotropy increased, the solidification pattern would transform from seaweed to degenerated dendrite and finally to tilted dendrite. © 2013 Chinese Physical Society.


Huang A.,Huazhong University of Science and Technology | Hu S.,Huazhong University of Science and Technology | Li Z.,Huazhong University of Science and Technology | Wang Y.,Beijing Hangxing Technology Development Co.
Applied Mechanics and Materials | Year: 2012

To figure out the elements distribution in the seams, laser welding was carried out on the Al plates which coating with Si powder and Cu powder respectively, then electronic probe was used to analyze the microstructure in the section of the seams. Results indicated that alloying elements distribution in the weld is heterogeneous under the metal liquid movement in welding pool and the elemental diffusion co-functioning. There are two high concentration regions on both sides of the weld centerline, the content at the center is low, slightly higher and more homogeneous at the bottom. The distribution of the alloy composition in the weld is related to the specific gravity of the alloying elements. Though the specific gravity of Si and aluminum matrix is similar, it can flow with the liquid metal in the pool, so the concentration changes of Si in the weld are larger. Elemental fluctuation keeps steady in the weld joint.


Ma R.-X.,University of Science and Technology Beijing | Wang M.-K.,Beijing Hangxing Technology Development CO. | Kang B.,University of Science and Technology Beijing | Wang Y.-G.,University of Science and Technology Beijing
Optoelectronics Letters | Year: 2011

Al and F co-doped ZnO (ZnO:(Al, F)) thin films on glass substrates are prepared by the RF magnetron sputtering with different F doping contents. The structural, electrical and optical properties of the deposited films are sensitive to the F doping content. The X-ray analysis shows that the films are c-axis orientated along the (002) plane with the grain size ranging from 9 nm to 13 nm. Micrographs obtained by the scanning electron microscope (SEM) show a uniform surface. The best films obtained have a resistivity of 2.16×10-3Ù.cm, while the high optical transmission is 92.0% at the F content of 2.46 wt.%. © Tianjin University of Technology and Springer-Verlag Berlin Heidelberg 2011.


Zhou T.,Northwestern Polytechnical University | Xiong Z.-Q.,Beijing Hangxing Technology Development Co. | Yao W.,Beijing Hangxing Technology Development Co. | Qin Y.,Beijing Hangxing Technology Development Co.
Tuijin Jishu/Journal of Propulsion Technology | Year: 2016

In order to reduce the elastic deformation of thin-walled workpieces with poor rigidity, when it is under the clamping force of tooling during the manufacturing process, a method of flexible tooling layout optimization for the thin-walled workpieces based on the improved ant colony algorithm is presented. Tooling layout optimization of positioning/supporting array is realized by combining finite element analysis with ant colony-genetic hybrid algorithm. The verification of examples shows that the optimal state of the topological configuration and distribution density of positioning/supporting array in the flexible tooling system can be achieved through optimization by the improved genetic-ant colony algorithm, thus obtaining the optimal flexible tooling layout for the thin-walled workpieces. The maximum deformation of the thin-walled workpieces can be reduced by 47%. © 2016, Editorial Office of Journal of Propulsion Technology. All right reserved.


Zhang H.,Tianjin University | Hu S.,Tianjin University | Shen J.,Tianjin University | Li D.,Tianjin University | Bu X.,Beijing Hangxing Technology Development Co.
Optics and Laser Technology | Year: 2015

Abstract Laser beam welding was used to weld dissimilar joints in BTi-6431S/TA15 titanium alloys. The effect of laser beam offset on microstructural characterizations and mechanical properties of the joints were investigated. Microstructural evolution of the joints was characterized by optical microscopy (OM) and X-ray diffraction (XRD). Tensile testing was conducted at room temperature and at 550°C. The results demonstrated that with the exception of some porosity, a good quality joint could be achieved. Martensite α' and acicular α structures were present in the fusion zone (FZ). The amount of martensite α' present with the -0.2 mm beam offset was less than that with the 0.2 mm beam offset. Acicular α and martensite α' transformations occurred in the high temperature heat-affected zone (HT-HAZ) of both the BTi-6431S and TA15 alloys. In the low-temperature heat-affected zone (LT-HAZ), the BTi-6431S and TA15 alloy microstructures exhibited a mixture of secondary α, primary α, and prior β phases. The microhardness values in the FZ followed the order: -0.2 mm> 0 mm> 0.2 mm. Tensile testing at room temperature and at 550°C resulted in fracture of the TA15 alloy base metal. The fracture morphology exhibited a ductile dimple feature. © 2015 Elsevier Ltd.


Liu F.,Beijing Hangxing Technology Development CO. | Wang J.,Beijing Hangxing Technology Development CO. | Ding J.,Beijing Hangxing Technology Development CO. | Xu Y.-F.,Beijing Hangxing Technology Development CO.
Journal of Applied Optics | Year: 2013

A refractive optical receiving antenna that was used in the multi-transmitter multi-receiver free space laser communication system was designed. The focal length of the antenna was 120.02 mm and relative aperture was 1:1.13. The antenna's working wavelength was 850 nm and wavelength range was 820 nm ~880 nm. The MTF of 0 field of view was 0.5 at the spatial frequency 50 lp/mm. In the transmitting antenna movable range of ±48 mm, the receiving antenna could receive the optical signal of 3 mrad divergence by using the avalanche photo-diode(APD) with 0.5 mm diameter of photosensitive surface. This refractive optical receiving antenna was composed of 4 spherical lenses, was simple in configuration, and could receive the optical signal from movable transmitting antenna.


Li D.,Tianjin University | Hu S.,Tianjin University | Shen J.,Tianjin University | Zhang H.,Tianjin University | Bu X.,Beijing Hangxing Technology Development Co.
Journal of Materials Engineering and Performance | Year: 2016

Laser beam welding (LBW) was applied to join 1-mm-thick dissimilar titanium alloys, Ti-22Al-25Nb (at.%) and TA15, and the microstructure and mechanical properties of the welded joints were systematically analyzed. Defect-free joints were obtained, and the fusion zone mainly consisted of B2 and martensitic α′ phases because of the uneven distribution of the β phase stabilizer and rapid cooling rate of LBW. The phase compositions of the heat-affected zone varied with the different thermal cycles during the welding process. The different microstructures of the dissimilar titanium alloys led to an unsymmetrical hardness profile, with the welded seam exhibiting the lowest value of 271 HV. In room-temperature tensile tests, the fractures all occurred preferentially in the fusion zone. The strengths of the joints were close to those of the base metal but with prominently decreasing ductility. In tensile tests performed at 550 °C, all the joints fractured in the TA15 base metal, and the strength and plasticity of the welds were equivalent to those of the TA15 base metal. © 2016, ASM International.


Song Z.,Tsinghua University | Wu A.,Tsinghua University | Yao W.,Beijing Hangxing Technology Development Co. | Zou G.,Tsinghua University | And 2 more authors.
Hanjie Xuebao/Transactions of the China Welding Institution | Year: 2013

Laser welding of TA15 and 5A06 alloys with 3 mm in thickness was conducted by focusing laser beam on titanium side, and the aluminum was melted through the heat conduction from titanium side. The effect of laser offset distance on microstructure and mechanical properties of the dissimilar butt joint was investigated. When the laser offset is 0.1-0.4 mm, fusion welded joint is formed. When the laser offset is 0.5 mm, fusion welded joint is formed on the upper side of the joint accompanying with Ti-Al intermetallic compounds. Welded-brazed joint is formed on the middle and bottom side of the joint accompanying with continuous Ti-Al intermetallic compounds layer with 1 μm thickness. The tensile strength of joints firstly increased and then decreased with the laser offset increasing. The highest average tensile strength of the joint reaches 181 MPa when the laser offset distance is 0.5 mm. The joints partly fracture in Ti-Al intermetallic compounds at the interface, and partly fracture at the fusion zone of aluminum alloy.


Yang X.,Beijing Hangxing Technology Development Co. | Li Z.,Beijing Hangxing Technology Development Co. | Bian Y.,Beijing Hangxing Technology Development Co. | Liu X.,Beijing Hangxing Technology Development Co. | Wang H.,Harbin Institute of Technology
Tezhong Zhuzao Ji Youse Hejin/Special Casting and Nonferrous Alloys | Year: 2015

A rapid casting method based on CAD/CAE/CAM and its application were presented. The casting process was designed rapidly with CAD technology at first, then numerical simulation and analysis with CAE technology was used to optimize and improve the casting process. Finally, the qualified mould was processed quickly with the help of patternless precise casting CNC manufacturing technology. Compared with the traditional casting method, the method can not only improve the response speed of casting, but also ensure the accuracy in size and internal quality of casting by improving the efficiency of casting process design and mould manufacturing, exhibiting a certain advantages in the development and production of single and small batch casting. ©, 2015, Journal Office of Special Casting and Nonferrous Alloys. All right reserved.

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