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Liang X.,Chongqing Vocational Institute of Electronic Engineering | Peng S.,No 59 Institute Of China Ordnance Industry
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2013

The structure characteristics of one shaft part with several oversized section change steps apply to starting motor of new energy vehicles, and its technological difficulties of cold extrusion technology are analyzed, also the design main points of its cold extrusion technology on technological process, forming blank and cold extruding die are elaborated. The compound cold extrusion dies of preforming, upsetting and cold extruding are designed. The compound cold extrusion process are simulated and analyzed by using the Three-dimensional plastic finite element and the numerical simulation analysis software. The structures, sizes and parameters of forming dies are optimized and improved, the forming problems are solved by this. The purposes of reducing the cost of production and processing greatly, and energy conservation and environmental protection are attained, and a strong foundation is laid for the mass industrialization in future. © 2013 Journal of Mechanical Engineering.

Zhang J.,University of Science and Technology Beijing | Zhang J.,Chongqing University of Technology | Zhang Y.,Chongqing University of Technology | Huang S.,No 59 Institute Of China Ordnance Industry
Chinese Journal of Mechanical Engineering (English Edition) | Year: 2011

58SiMn steel can be used as a kind of material for projectile-like barrel parts. During producing barrel parts, the microstructure of the barrel parts will be changed due to its hot deformation at certain high temperature, which resulted in the variety of the part's mechanical properties. It is necessary to optimize the parameters for recrystallization process by prediction and simulation. The double-pass hot compression tests were conducted using Gleeble 1500 System at different deformation temperature, strain rate and pre-strain. Effect of pre-strain, deformation temperature on the curve of stress-strain has been analyzed. The static recrystallization fraction of double-pass hot deformation was computed and analyzed using compensation test. The actual grain size was measured by metallographic method using oxidation process, which overcomes the difficulty in revealing grain size of 58SiMn steel. The oxidation process was the method of heating the martensite in very fast speed and use of its microstructure inherent characteristic and regarding the size of austenite grain as the maximum of martensite plate. Using regression of the experimental data, the mathematical model of static recrystallization is set up. The average grain size of 58SiMn steel during hot deformation was calculated by deform-3D software and verified by experiment. The results show that the rate of static recrystallization was in direct proportional to the pre-strain of the steel. The grain size decreased with the increase of holding time at low deformation temperature 1173 K and pre-strain 0.10. The mathematical model proposed could be used for predicting the static recrystallization behaviors of 58SiMn steel. Copyright © 2011 Chinese Journal of Mechanical Engineering.

Yu X.,Chongqing University | Jiang B.,Chongqing University | Jiang B.,Chongqing Academy of Science and Technology | Yang H.,Chongqing University | And 5 more authors.
Applied Surface Science | Year: 2015

Oxidation properties of Mg-Y-Sn, Mg-Y and Mg-Sn alloys at 500 °C and corrosion behavior of the oxidized alloys were investigated. The results showed that Mg-Y-Sn and Mg-Y alloys exhibit better oxidation resistance compared with pure Mg and AZ31. Y-enriched oxide films were formed on the surfaces of Mg-Y-Sn and Mg-Y alloys after being oxidized at 500 °C for 6 h and the films are mainly composed of Y2O3 and MgO according to X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. The compact surface oxide film can effectively protect the matrix from oxidizing. Simultaneously, the electrochemical corrosion and immersion tests showed that corrosion resistance of the oxidized Mg-Y-Sn and Mg-Y alloys has been enhanced compared with the initial unoxidized alloys. Y plays a decisive role in improving the protective property of the oxide film. © 2015 Elsevier B.V. All rights reserved.

Xing X.,Xi'an Modern Chemistry Research Institute | Zhao S.,Xi'an Modern Chemistry Research Institute | Huang W.,No 59 Institute Of China Ordnance Industry | Li W.,Xi'an Modern Chemistry Research Institute | And 3 more authors.
Journal of Thermal Analysis and Calorimetry | Year: 2015

Abstract The thermal decomposition behavior of high explosive CL-20 was determined by microcalorimetry method, and the thermal decomposition behaviors of CL-20 with BTATz or BTATz and aluminum at different heating rates were studied at the same time. The kinetic and thermodynamic parameters were obtained from the analysis of the heat flow data. Critical temperature of thermal explosion (Tb) and initial decomposition temperature (Tp0) were calculated to show the effect of the aluminum on the whole system. © Akadémiai Kiadó, Budapest, Hungary 2015.

Xie H.,Chongqing University | Xie H.,Yangtze Normal University | Jiang B.,Chongqing University | Jiang B.,Chongqing Academy of Science and Technology | And 4 more authors.
Tribology International | Year: 2016

The effects of the base lubricant with and without nanoparticles on the tribological behavior of magnesium alloy/steel contacts were investigated using a reciprocating sliding ball-on-flat tribometer. Three sets of contact conditions were used to evaluate the effect of concentration, the capacity of carrying load and the stability of the lubrication film, respectively. The results showed that the tribological properties of the base lubricant have been improved by adding the nanoparticles. As compared with the SiO2 nanolubricants, the positive effect of the MoS2 nanolubricants is more pronounced in terms of the load carrying capacity and the lubrication film stability. Mechanisms by which the nanolubricants improve tribological behaviors are discussed. © 2015 Elsevier Ltd.

Dai J.,Chongqing University | Jiang B.,Chongqing University | Jiang B.,Chongqing Academy of Science and Technology | Li X.,Chongqing University | And 6 more authors.
Journal of Alloys and Compounds | Year: 2014

The formation of Al-Ce intermetallic compounds (IMCs) during interdiffusion of Mg-Al/Mg-Ce diffusion couples prepared by solid-liquid contact method was investigated at 623 K, 648 K and 673 K for 24 h, 48 h and 72 h, respectively. During the whole diffusion process, Al was the dominant diffusing species, and it substituted for Mg of the Mg-Ce substrate. Five Al-Ce IMCs of Al4Ce, Al11Ce3, Al3Ce, Al2Ce and AlCe were formed via the reaction of Al and Ce. The formation of Al4Ce as the first kind of IMC was rationalized on the basis of an effective Gibbs free energy model. The activation energy for the growth of the total diffusion reaction layer was 36.6 kJ/mol. © 2014 Published by Elsevier B.V.

Luo J.,Chongqing University | Zhao G.,Chongqing University | Luo Q.,Lianyuan Iron and Steel Co. of Hunan Hualing Group | Wang X.,Chongqing University | Xu X.,No 59 Institute Of China Ordnance Industry
Hsi-An Chiao Tung Ta Hsueh/Journal of Xi'an Jiaotong University | Year: 2010

Inertial radial friction welding process was adopted to weld 35CrMnSi and T3. The interface microcosmic binding characteristics were observed by SEM. The element diffusion near the interface was detected by EDS. The results show the tightly connected contact surface of 35CrMnSi/T3 with obviously wavy occlusion at flywheel rotation speed of 3 000 r/min. The elements diffusion and dissolution through the interface occur, and the metallurgical bonding forms. The diffusion distance of Fe atoms into copper matrix gets to 33 μm and Cu atoms into Fe matrix about 3 μm. In addition, the adverse effect of oxygen on friction welded joints is inhibited by the evident plastic deformation of the contact surfaces in radial friction welding process.

Peng J.,Chongqing University | Tao J.,No 59 Institute Of China Ordnance Industry | Tong X.,Chongqing University | Pan F.,Chongqing University
China Foundry | Year: 2014

For the large magnesium alloy ingot, there is a considerable difference in cooling rate of different parts in the ingot, which leads to non-uniform distribution of the secondary phases, solute segregation and tensile properties. In the present research, an heavy AZ61 alloy ingot with a diameter of 500 mm was made by semi-continuous casting. The microstructure and mechanical properties at different positions along the radial direction of the large ingot were investigated by using an optical microscope (OM), a scanning electron microscope (SEM), an energy dispersive spectroscope (EDS), and a micro-hardness tester. The results indicate that the microstructure of the AZ61 ingot is non-uniform in different locations. It changes from equiaxed to columnar grains from the center to the edge; the average grain size gradually reduces from 1,005 μm to 763 μm, the secondary dendrite arm spacing reduces from 78 μm to 50 μm, and the Mg17(Al,Zn)12 phase is also refined. The micro-hardness value increases from 55.4 HV at the center to 72.5 HV at the edge of the ingot due to the microstructure differences, and the distribution of micro-hardness at the edge of the ingot is more uniform than that in the center. The tensile properties at room temperature show little difference from the center to the edge of the ingot except that the elongation at the edge is only 3.5%, much lower than that at other areas. The fracture mechanism is ductile fracture at the center and cleavage fracture at the edge of the ingot, and at the 1/2 radius of the ingot, a mixture of ductile and cleavage fracture is present.

Wang C.-P.,No 59 Institute Of China Ordnance Industry | Wang C.-P.,University of Science and Technology Beijing | Tang Z.-J.,Nanjing University of Aeronautics and Astronautics | Mei H.-S.,No 59 Institute Of China Ordnance Industry | And 3 more authors.
Rare Metals | Year: 2015

The effects of isothermal holding process on the microstructure evolution of semi-solid 7075 strength aluminum alloy produced by the recrystallisation and partial remelting (RAP) process were investigated. Tensile mechanical properties of as-received and thixoformed alloys at room temperature were examined. The results show that the microstructure of as-received alloy exhibits remarkable orientation along the deformation direction. With the increase of isothermal holding time, the solid particle grain size continuously increases and the degree of spheroidization also improves. Coalescence mechanism is dominant when reheated at 595 °C and Ostwald ripening mechanism is dominant when reheated at 615 °C in the semi-solid state. A lower coarsening rate is observed for 615 °C (coarsening rate K = 391 μm3·s−1) compared with the coarsening rate for 595 °C (coarsening rate K = 501 μm3·s−1). The RAP 7075 aluminum alloy can be successfully thixoformed and the filling of components is good after thixoforming. The thixoformed components exhibit favorite mechanical properties. © 2013, The Nonferrous Metals Society of China and Springer-Verlag Berlin Heidelberg.

Su Y.,No 59 Institute Of China Ordnance Industry | Zhang L.,No 59 Institute Of China Ordnance Industry | Zhong Y.,No 59 Institute Of China Ordnance Industry
Journal of the Chinese Society of Corrosion and Protection | Year: 2016

The microstructure, corrosion behavior and the influence of corrosion on mechanical performance of 5A90 Al-Li alloy and 2D12 alloy were studied comparatively by means of X-ray diffraction, metallurgical analysis, scanning electron microscopy and marine atmospheric exposure test, while the relevant corrosion mechanism was also discussed. The results showed that the strengthening phases δ ′-Al3Li and T-Al2MgLi of 5A90 Al-Li alloy are fine and dispersed quite uniformly. 5A90 Al-Li alloy showed corrosion characteristics in micro-scale apparently different from 2D12 alloy, i.e. the corrosion of the former occurred simultaneously at grain boundaries and in grains. The corrosion process of 5A90 Al-Li alloy did not follow the power function in terms of corrosion mass loss. The mechanical performance degradation of 5A90 Al-Li alloy due to corrosion is apparently faster than that of 2D12 alloy. The fracture manner of 5A90 Al-Li alloy is mainly dimple fracture, while the environmental corrosion promotes the transition from ductile fracture to intergranular brittle fracture. © 2016, Chinese Society of Corrosion and Protection. All rights reserved.

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