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Wang X.N.,Soochow University of China | Sun Q.,AVIC Shenyang Aircraft Corporation Ltd. | Du L.X.,Northeastern University China | Di H.S.,Northeastern University China
Reviews on Advanced Materials Science | Year: 2013

In order to realize the weight reduction of the carriage of heavy-duty truck, the 700 MPa hot-rolled high-strength C-Mn steel plate was successfully developed on 1750 mm hot-strip mills to replace the Q345 steel plate which was originally used for carriage. The microstructure of the plate was composed of fine-grained ferrite, carbides distributed along the ferrite grain boundaries, a little pearlite with 40~50 nm lamellar spacing and a mount of bainite. The yield and tensile strengths of the plate were about 680 MPa and 740 MPa, respectively. The value of n, rm and hole expansion rate (λ) were 0.12, 0.8, and 60%, respectively. The plate has great low temperature impact toughness and weldability. The strengthening mechanisms of the plate were mainly governed by fine-grained strengthening and (Ti,Nb)C nano-precipitates strengthening. If the carriage of heavy-duty truck was constructed by new plate, the weight could reduce 20% due to the thickness reduction. For further reduction of the weight of the carriage, the optimization design was carried out by finite element method. Then, the weight of the carriage could be reduced 12%. © 2013 Advanced Study Center Co. Ltd.

Lu Z.-W.,AVIC Shenyang Aircraft Corporation Ltd. | Chen X.,Aerospace Research Institute of Materials And Processing Technology | Liu C.-J.,Aerospace Research Institute of Materials And Processing Technology
Dongbei Daxue Xuebao/Journal of Northeastern University | Year: 2014

The connector pin failure was found between transition positions after the plane served for 1 114 h. Macro- and micro-fracture analysis, EDS analysis and hardness were carried out and compared with the man-made fracture. The effect of poor contact state on stress distribution was further studied by finite element method(FEM). The results showed that the failure of connector pin is fatigue fracture. The fracture is mainly caused by excessive solder, addition assembly stress and vibration stress vertical breadth of connector pin. It is suggested that the manufacture processes of solder and assembly should be controlled, the plate and connector pin should be fitted tightly, so the assembly stress can be reduced. ©, 2014, Northeastern University. All right reserved.

Geng M.,AVIC Shenyang Aircraft Corporation Ltd. | Liu Y.,Shenyang Aerospace University
55th Israel Annual Conference on Aerospace Sciences 2015 | Year: 2015

This paper proposes a novel method with harmonic wavelet packet and Decision-Tree Relevance Vector Machine (DT-RVM). First, calculate the vector energy with wavelet coefficients after the vibration signals have been decomposed with harmonic wavelet packet. The feature vector is prepared after the vector energy is standardized. Second, the multi-classification model is established with the incorporation of three two-classification sub-models in order to diagnose normal state, inner race fault, roller fault and outer race fault. Finally, the proposed model is illustrated with the vibration data from the roller bearing stand of electric engineering lab in American Case Western Reserve University. Experimental results show the proposed model possesses higher accuracy and efficiency compared with conventional Support Vector Machine (SVM) model. Copyright © (2015) by Technion Israel Institute of Technology. All rights reserved.

Zhang B.-G.,Harbin Institute of Technology | Chen G.-Q.,Harbin Institute of Technology | Zhang C.-G.,Harbin Institute of Technology | Ni J.-Q.,AVIC Shenyang Aircraft Corporation Ltd.
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2011

Electron beam welding was carried out between aluminum alloy and steel with Ag interlayer. Seam morphology, structure and mechanical properties of the joints were investigated with different action positions of the electron beam spot. The results show that with the increment of the beam offset to the silver side from the interface between silver and steel, the seam morphology was improved, and the porosity in the Ag interlayer vanished. A transition layer mainly composed of Ag 2Al and Al eutectic was formed at the interface between silver and aluminum, and became thin and spiccato as the beam offset increased. When the beam offset was too large, two IMC layers composed of FeAl and FeAl 3 respectively were formed at the interface between steel and Ag interlayer. The optimal beam offset was 0.2 mm, and the maximum tensile strength of the joint was 193 MPa, 88.9 that of the aluminum alloy, and the fracture occurred at the interface between steel and Ag interlayer. © 2011 The Nonferrous Metals Society of China.

Hu J.,Northeastern University China | Du L.-X.,Northeastern University China | Wang J.-J.,Northeastern University China | Gao C.-R.,Northeastern University China | And 3 more authors.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2013

Controlled rolling followed by accelerated cooling was carried out in-house to study the microstructure and mechanical properties of a low carbon dual-phase steel. The objective of the study described here was to explore the effect of cooling schedule, such as air cooling temperature and coiling temperature, on the final microstructure and mechanical properties of dual-phase steels. Furthermore, the precipitation behavior and yield ratio are discussed. The study demonstrates that it is possible to obtain tensile strength and elongation of 780 MPa and 22 pct, respectively, at the two cooling schedules investigated. The microstructure consists of 90 pct ferrite and 10 pct martensite when subjected to moderate air cooling and low temperature coiling, such that the yield ratio is a low 0.69. The microstructure consists of 75 pct ferrite and 25 pct granular bainite with a high yield ratio of 0.84 when the steel is directly cooled to the coiling temperature. Compared to the conventional dual-phase steels, the high yield strength is attributed to precipitation hardening induced by nanoscale TiC particles and solid solution strengthening by high Si content. The interphase precipitates form at a suitable ledge mobility, and the row spacing changes with the rate of ferrite transformation. There are different orientations of the rows in the same grain because of the different growth directions of the ferrite grain boundaries, and the interface of the two colonies is devoid of precipitates because of the competitive mechanisms of the two orientations. © 2013 The Minerals, Metals & Materials Society and ASM International.

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