Author L.J. Chen1
,
2)
,
G. Yao1)
,
Z.G. Wang1) and J.F. Tian1) 1) State Key Laboratory for Fatigue and Fracture of Materials
,
Institute of Metal Research
,
The Chinese Academy of Sciences
,
Shenyang 110015
,
China2) Department of Metallic Material Engineering
,
Shenyang Polytechnic University
,
Shenyang 110021
,
China Manuscript received 18 October 1998
金属学报(英文版)
The cyclic stress response and lowcycle fatigue life for wrought nickelbased superalloy GH4049 were investigated in the temperature range from 500 to 800 The relationship between the strain amplitude and the number of stress reversals was given. The behavior of cyclic hardening was observed for higher strain amplitudes at all testing temperatures and the lowcycle fatigue life generally decreased with increasing testing temperature for the same strain range. In addition, fracture surfaces of the fatigued samples were examined by using a scanning electron microscope.
关键词:
superalloy
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null
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Author F.Z. Shen. G.X. Ma and X. Ling Nanjing University of Chemical Technology
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Nanjing 210009
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China X. Yang Jing Ling Petrochemical Corporation
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Nanjing 210046
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China X.Z. Zhang
,
J. Ruan and Y. Lu Lutianhua Group Incorporated
,
Luzhou 646300
,
China Manuscript received 18 October 1998
金属学报(英文版)
Two methods for predicting residual life of high temperature furnace tubes are studied. One is testanalysis method that is mainly based on the creep rupture tests on postservice specimens. Specimens were taken from the tubes, which had been in service for different times. KachanovRobinsons damage summation concept is employed, however with a modified factor K(ts) to account for prior damage in the specimens. If the foregone total life corresponds with real condition, all of the test data modified by K(ts) should be distributed uniformly nearby the master curve of the new material. The other iscomputer simulation method that considers all of the operating conditions that influence the life. The finite element method (FEM) with iterative calculation is used in the analysis. The variation rates of critical damage element along the wall thickness are determined as a function of the service temperature and current damage. A special program designed based on the method predicts well the residual life of fu
关键词:
residual life
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Author S.H. Bai
,
S.R. Qiao
,
S.R. Zhou and M.K. Kang Faculty 401
,
Northwestern Polytechnical University
,
Xian 710072
,
China Manuscript received 18 October 1998
金属学报(英文版)
In this paper, the influence of loading rate and specimen height on flexural strength of Al2O3 at high temperatures has been studied by three-point bending method. The experimental results show that the flexural strength of Al2O3 decreases with increasing specimen height at room temperature, and it tends to stability when height increases to a certain degree (h=5mm in this paper), while the flexural strength of Al2O3 variates unapparently at high temperature with increasing height. There is a critical loading rate R . c. When loading rate R . is less than R . c, the flexural strength of Al2O3 increases with increasing loading rate and it drops sharply when loading rate is higher than R . c. The sensitivity of flexural strength to the loading rate decreases with elevating temperatures.
关键词:
loading rate
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null
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Yang LUO
材料科学技术（英文）
Due to continued growth in key markets, a broadening of application base and performance improvements, the market demands of NdFeB magnet increased steadily in 1998, and the global output of sintered NdFeB magnet exceeded 10,000 t, in spite of the economic recession in Asia. In 1998 China produced 3,850 t sintered NdFeB block magnet, with an annual growth rate of +22% over the output in 1997.
关键词:
Author X.A. Zhang1)
,
H.Q. Xia1)
,
Z.T. Wu1)
,
Y.F. Han1)
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R. Shi2) and G.X. Hu2) \= 1) Mechanical Properties Laboratory
,
Beijing Institute of Aeronautical Materials
,
Beijing 100095
,
China2) The State Education Commission Open Research Laboratory for High Temperature
金属学报(英文版)
Materials and Testing, Shanghai Jiao Tong University, Shanghai 200030, ChinaManuscript received 18 October 1998 The threestage creep behavior of DD3 single crystal superalloy had been studied. The results show that the creeprupture properties of DD3 single crystal satisfy the requirements for high performance turbine blade application. The influence of crystal orientation on the creeprupture property of DD3 single crystal was tested and discussed. An engineering criterion to evaluate the regimes of secondary and tertiary creep is proposed, and this method gives a reasonable result for practical applications. The fractography and TEM micrography of the tested specimens had been studied, and it is determined that the glidecontrolled creep is the basic creep mechanism of DD3 single crystal at intermediate temperature, but the thermally activated processes become dominant at higher temperature.
关键词:
threestage creep curve
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LIANG Yong LI Ruiguo Institute of Metal Research
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Academia Sinica
,
Shenyang 110015
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ChinaInstitute of Corrosion and Protection of Metals
,
Aademia Sinica
,
Shenyang
,
110015
,
China
材料科学技术（英文）
Recent advances in laser coating technology including laser cladding,laser surface alloying and laser vapour deposition in China are reviewed in this paper.
关键词:
laser
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null
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