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Shen Z.-Q.,Key Laboratory for Liquid Solid Structural Evolution and Processing of Materials Ministry of Education | Tian X.-L.,Key Laboratory for Liquid Solid Structural Evolution and Processing of Materials Ministry of Education | Zheng H.-L.,Key Laboratory for Liquid Solid Structural Evolution and Processing of Materials Ministry of Education | Li T.-T.,Key Laboratory for Liquid Solid Structural Evolution and Processing of Materials Ministry of Education | And 3 more authors.
Zhuzao/Foundry | Year: 2012

The morphology, size and composition of spheroidal graphite(SG) nuclei were researched by casting a series of different samples which were treated by the same nodulizer and different inoculants. Wedge and chill test pieces used for chemical analysis were cast. The observation of the SG nucleus was done by using of FE-SEM. The results indicate that the morphologies of SG nuclei are different, including spherical, conical, polygonal and so on. The SG nucleus consist of sulfide, oxide and carbide, and the size is about 0.6-7 μm. Not only single core but also double and multiple cores are found in SG nuclei. The mismatch between most nuclei compounds and graphite is small, so compounds are good nucleating sites for SG. For the δ between the SiO 2 and graphite is large, SiO 2 can act as spherical graphite substrate only after the combination with SiC. Source


Li X.-Q.,Beihang University | Li X.-Q.,Beijing Hangxing Machinery Manufacturing Corporation | He D.-H.,Beihang University
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2013

To accurately describe the mechanical properties of aluminium alloy sheet during deformation, an inverse identification was presented to deal with material parameters from the popular punch stretch test. In the identification procedure, the optimization strategy combines finite element method (FEM), Latin hypercube sampling (LHS), Kriging model and multi-island genetic algorithm (MIGA). The proposed approach is used on material parameter identification of aluminium alloy sheet 2D12. The anisotropic yield criterion Hill'90 is discussed. The results show that the Hill'90 anisotropic yield criterion with identified anisotropic material parameters has a good potential in describing the anisotropic behaviours. It provides a way to obtain the material parameters for FE simulations of sheet metal forming. © 2013 The Nonferrous Metals Society of China. Source


Jiang S.-S.,Harbin Institute of Technology | He X.-D.,Harbin Institute of Technology | Zhang K.-F.,Harbin Institute of Technology | Gao P.,Harbin Institute of Technology | Li B.-Y.,Beijing Hangxing Machinery Manufacturing Corporation
Hangkong Cailiao Xuebao/Journal of Aeronautical Materials | Year: 2012

The ZrO 2-TiO 2 ceramic die with controllable linear expansion coefficient (LEC) and the high precision superplastic forming were studied. The influence of TiO 2 fraction and relative density on linear expansion coefficient of ZrO 2-TiO 2 ceramic was analyzed. The Turner model was modified and the relative density was introduced into the model. The forming accuracy of ceramic die with the similar LEC to TC4 titanium alloy was measured. The ZrO 2-TiO 2 deep cylinder ceramic die was fabricated and its performance was evaluated by the superplastic forming experiment at 925°C. The results show that the LEC decreases with the increment of volume fraction of TiO 2 and increases with the rising of relative density. The modified Turner model more accurately predicted. Using the ZrO 2-TiO 2 ceramic die with optimal LEC, the forming accuracy deviation significantly reduced and not exceed of 0.1%. The ceramic die owns enough sufficient thermal mechanical properties and excellent performance. Source


Qu F.-S.,Chongqing University | Lu Z.,Harbin Institute of Technology | Zhang K.-F.,Harbin Institute of Technology | Li B.-Y.,Beijing Hangxing Machinery Manufacturing Corporation
Cailiao Gongcheng/Journal of Materials Engineering | Year: 2011

The Inconel718 superalloy with multi-sheet coreboard structure was manufactured by LBW+SPF complex technology. In order to enhance the security of multi-sheet coreboard structure, the heat treatment processing was studied. The results show that Laves precipitation phase which contains higher content Nb element in the welding process of Inconel718 superalloy. After SPF process, Nb segregation in the weld is partly dissolved. The heat treatment of solution treatment at 980°C/30 min can make δ phase dissolve thoroughly into the γ phase and the Nb content of the dendritic in the weld joint steps up. The heat treatment of solution treatment at 1080°C/30 min can make Laves phase dissolve and solve the problem of segregation Nb. Grain size of Inconel718 superalloy by solution treatment 1080°C grows up greatly. The yield strength compared after superplastic forming decreases slightly. Source


Yao W.,Beijing Hangxing Machinery Manufacturing Corporation | Wang Z.,Beijing Hangxing Machinery Manufacturing Corporation | Li H.,Beijing Hangxing Machinery Manufacturing Corporation | Wang C.,Huazhong University of Science and Technology
Hanjie Xuebao/Transactions of the China Welding Institution | Year: 2011

In this paper, double-layers laser-MIG welding of thick aluminum alloy method was put forward. It welds two layers: the first layer padding welding, to solve the problem of inadequate weld penetration; second welding surface for the cap to address the problem of the poor weld shape. The results showed that: rated at 4 kW lasers when the composite layer by laser-MIG welding materials, welding ZL114A deeps up to 10 mm, average joint tensile strength is 238 MPa, tensile strength is greater than 80% of the base metal. Double-layers laser-MIG welding method of welding, a simulation of a cylindrical pieces of aerospace products, forming a good weld, penetration up to 9 mm. With no crack, no incomplete penetration and lack of fusion, no visible inclusions, defects is mainly chain-like porosity, pore diameter less than 1mm, almost no distortion after welding. Source

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