DENG Rongying ZHOU Aihua JIANG Huaiqing LI Chunxiu Institute of Mechanics
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Academia Sinica
,
Beijing
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ChinaZHANG Liqing
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SUN Yutian Beijing Institute of Engineering
,
Beijing
,
China [Originally published in ACTA METALL SIN(CHINESE EDN)25(3)1989 pp A219—A225
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Associate Profes sor
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Institute of Mechanics
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Academia Sinica
,
Beijing
,
China
金属学报(英文版)
The effect of pearlite interlamellar spacing(d)from 0.31 to 0.77 μm of T8 steel on fatigue crack propagation near threshold has been investigated at different stress ratios(R).The closure stress intensity factor(K_(cl)),the threshold value(ΔK_(th))and crack tip opening dis- placement range(ΔCOD)were measured.The results show that pearlite interlamellar spac- ing in this range has no effect on K_(cl),but has effect on the threshold value in low stress ratio. The threshold value is higher for materials with larger interlamellar spacing.No matter what the stress ratio is,during the propagation near threshold,the propagation rate will be the same,provieded the crack tip opening displacement range is the same. Metallurgical examinations were also carried out to show that the crack propagation path is sensitive to mierostructure.The crack always propagates along either boundary of pearlite colony or ferrite lamellar in pearlite.
关键词:
pearlitic steel
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ZHANG Dengxia MA Chenghui CAI Ming Institute of Mechanics
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Academia Sinica
,
Beijing
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ChinaAI Baoren ZHANC Jinyuan ZHU Ruizhen LIU Chunlan Central Iron and Steel Research Institute
,
Ministry of Metallurgical Industry
,
Beijing
,
China Associate Professor
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Institute of Mechanics
,
Academia Sinica
,
Beijing 100080
,
China
金属学报(英文版)
Observations of microstructure of explosive compacts made of Al or Al-Li alloy powders by atomization with water,nitrogen or ultrasoic Ar gas were carried out under optical and scanning electron microscopes.The rsults indicate that super quality explosive compact can only be obtained by powders of which the thickness of the oxide layer is less than 30 nm.
关键词:
Al powder
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GAO Juxian ZHANG Ke ZHENG Zhemin Institute of Mechanics
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Academia Sinica
,
Beijing
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China GAO Juxian Associate Professor
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Institute of Mechanics
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Academia Sinica
,
Beijing 100080
,
China
金属学报(英文版)
Two-dimension consolidation under the cylindrical converging shock wave has been studied. The major parameters influenced on the explosive consolidation quality are the specific energy,detonation pressure and specific impulse.It seems to be favourable to improving con- solidation quality by a lower but slightly higher than critical detonation pressure and a high specific impulse.
关键词:
explosive consolidation
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Q. Y. Liu1
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2) W. D. Fei2) and N. G. Liang1) 1) LNM
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Institute of Mechanics
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The Chinese Academy of Sciences
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Beijing 100080
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China 2) Schoolof Materials Science and Engineering
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Harbin Institute of Technology
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Harbin 150001
,
China
金属学报(英文版)
heinteracteach other among three kindsofthermalresidualstresses were analyzed firstly. Theresultsshown thatthe presenceof microstressandthermal mismatch stresshad noinflu enceon the measurement of macrostress, but macrostress can affect the measured value of thermal mismatch stress. Theeffectofthicknessofspecimen on thermalresidualstresses was discussed. Macrostresscan be neglected in thin specimen, thermal mismatch stressincreased with quenchingtemperatureincreasing, andobtainedtheir maximum valuesat400 ℃,then decreased . Forthethickspecimen, thecompressive macrostressatthesurfaceincreased with the quenching temperature increasing. The changing tendency of thermal mismatch stresswith quenchingtemperature wasquite differentcompared withthethinspecimens, which ob tainedtheir minimum valueat400℃.
关键词:
thermalresidualstresses
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