ZHAO Zengqi CHEN Feixia YANG Dazhi BAO Er ** Physical Laboratory
,
Baotou Research Institute of Rare Earth
,
Baotou
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014010
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China*** Dept.of Materials Engineering
,
Dalian University of Technology
,
Dalian
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116024
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China**** Dept.of Materials Engineering
,
Yanshan Uni
材料科学技术（英文）
The present investigation showed that the re- laxation peak at about 200℃ (f≈1Hz) was related to bainitic transformation in a CuZnAl alloy.The peak decreased when bainite precipitated.The activation energy of the peak was the same as the apparent activation energy of bainitic transforma- tion.According to the relations between the peak and the bainitic transformation,the mechanism of the peak has been discussed.
关键词:
internal friction
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null
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null
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null
Corrosion Science
Stress corrosion cracking growth rate of uni-directionally cold-rolled 316L stainless steel was monitored in simulated PWR primary water with different dissolved hydrogen (DH) concentrations at 320 degrees C. Crack growth rate at a DH of 0.16 cm(3) (STP) H(2)/kg H(2)O is close to that at 5 cm(3) (STP) H(2)/kg H(2)O. Crack growth rate at 30 cm(3) (STP) H(2)/kg H(2)O is about one fourth of that at 5 cm(3) (STP) H(2)/kg H(2)O or two times of that at 50 cm(3) (STP) H(2)/kg H(2)O. Electron back scattering diffraction results show typical intergranular SCC along high angle boundaries with high levels of deformation. (C) 2011 Elsevier Ltd. All rights reserved.
关键词:
Stainless steel;SEM;Stress corrosion;Hardening;Potential parameters;high-temperature water;dependence;alloys;growth
V. Arumugam
金属学报(英文版)
Acoustic emission (AE) can be used for in situ structural health monitoring of the composite laminates. One of the main issues of AE is to characterize different damage mechanisms from the detected AE signals. In the present work, pure resin and GFRP composites laminates with different stacking sequences such as 0°, 90°, angle ply[±45°], cross-ply [0°/90°] are used to trigger different failure mechanisms when subjected to tensile test with AE monitoring. The study of failure mechanisms is facilitated by the choice of different oriented specimens in which one or two such mechanisms predominate. Range of peak frequencies in each orientation is investigated using FFT analysis. Fast Fourier Transform (FFT) enabled calculating the frequency content of each damage mechanism. Randomly selected hits from each range of peak frequencies for the specimens with different orientations subjected to tensile test with AE monitoring are analyzed using short time FFT (STFFT) analysis. STFFT analysis is used to highlight the possible failure mechanism associated with each signal. The predominance of failure modes in each orientation is useful in the study of discrimination of failure modes in composite laminates from AE data.
关键词:
Composite materials
Applied Mathematics and Computation
In this paper, the modified Korteweg-de Vries (mKdV) equation with variable coefficients (vc-mKdV equation) is investigated via two kinds of approaches and symbolic computation. On the one hand, we firstly reduce the vc-mKdV equation to a second-order nonlinear nonhomogeneous ODE using travelling wave-like similarity transformation. And then we obtain its many types of exact fractional solutions with one travelling wave-like variable by applying some fractional transformations to the obtained nonlinear ODE. On the other hand, we reduce the vc-mKdV equation to two nonlinear PDEs with variable coefficients using the anti-tangent and anti-hypertangent function transformations, respectively. And then we given its many types of exact solutions with two different travelling wave-like variables by studying the obtained nonlinear PDE with variable coefficients. (c) 2008 Elsevier Inc. All rights reserved.
关键词:
modified Korteweg-de Vries ( mKdV);equation with variable coefficients;exact solutions;de-vries equation;elliptic function solutions;nonlinear;schrodinger-equation;differential-equations;soliton
WANG Xu
,
ZHANG Shouhua
,
CUI Peiyong Beijing University of Science and Technology
,
Beijing
,
China. Central Iron and Steel Research Institute
,
Beijing
,
China.
材料科学技术（英文）
Rolling Contact Fatigue(RCF) is a cumulative damage phenomenon when metals are subjected to repeated contact stresses. The fomation of pitting on the contact surface is the result of the rolling contact fatigue. The morphologies of rolling contact fatigue fracture of the har- dened steels (86CrHoV7, 42CrMo) show that strong resemblance in fractuye mechanisms exists between rolling contact fatigue and uni-axial fatigue. Since fatigue striations are hardly observed in hardened steels under uni-axial fatigue, it is interesting to note that the state of stress in rolling contact fatigue is more favor- able to ductile fractures than in uni-axial fatigue.
关键词:
rolling contact
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null
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null
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null
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null
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null
YANG Li-po
,
YU Bing-qiang
,
YU Hua-xin
钢铁研究学报(英文版)
In specific condition, when wrapping angle of cold rolling strip covering surface of shape detecting roll dynamically changes, online radial compression of the shape detecting roll is changed too, and it seriously affects online shape detecting precision of cold strip. Based on the latest intelligent shape meter developed by Yanshan University, using PSO-BP neural network and actual working condition datum, the cold strip online dynamic wrapping angle compensation model is established, and successfully applied in 1250 mm 6-high cold mill, remarkable results are achieved. The error between calculated values and measured values of total tensions is within 3%.
关键词:
cold rolling strip
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shape detecting
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wrapping angle
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compensation
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shape meter
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cold mill
Z.L. Chang
,
J.L. Song
,
N.H. Hao
金属学报(英文版)
Equal cross section lateral extrusion (ECSLE) is an effective method realizing pure shear deformation. The in uence of friction factor on the deformation uniformity of ECSLE was investigated with rigid plastic nite element method. The result shows that the non-uniform deformation in extrusion is caused mainly by the friction be- tween workpiece and die. The higher the friction factor is, the more uneven plastic deformation resulted in extruded workpiece. The relation curve of deformation uni- formity vs. friction factor was drawn based on the analysis result. The curve can be used as a basis of ECSLE process design.
关键词:
equal cross section lateral extrusion
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null
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null
李松林
,
刘燚
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刘怀菲
,
崔建民
,
陈仕奇
中国有色金属学报
分别应用Uni-Ball-Mill 5和XQM-4变频行星式球磨机将Mg粉和Fe粉在氢气中直接球磨合成三元储氢相Mg2FeH6.采用球磨罐中的氢压降、X射线衍射谱、扫描电镜、热分析、吸放氢测试等测试手段研究了不同球磨方式对纳米晶Mg2FeH6储氢材料的合成结果.结果表明,XQM-4变频行星式球磨机球磨150 h,Mg2FeH6相的产率(质量分数)接近70%;在100 kPa氢压下,380 ℃放氢量为2.66%,粉末呈片状,晶粒在7 nm以下.而采用Uni-Ball-Mill 5球磨机P2方式球磨270 h,Mg2FeH6相的产率仅为39.1%,100 kPa氧压下,350 ℃放氢量为1.15%,粉末呈球状.两者的差别可能源于前一种球磨方式具有更高的球磨合金化效率.
关键词:
储氢材料
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机械合金化
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燃料电池
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纳米材料
DONG Yong-gang
钢铁研究学报(英文版)
In rail rolling by universal mill, a simplified 3-dimention theoretical model has been built firstly. The kinematically admissible velocity field of the web, head and base of rail have been determined respectively, moreover the corresponding strain rate field and the strength of shear strain rate have been also obtained. Then the plastic deformation power of corresponding deformation zone, the powers consumed on the velocity discontinuity surface and the powers generated for backward slip and forward slip have been proposed. According to the upper-bound method, the roll force of horizontal roll and two vertical rolls can be obtained. Moreover, The process of 18kg/m light rail and 60kg/m heavy rail universal rolling have been simulated by rigid-plastic FEM(finite element method) for verifying the theoretical model. And the universal rolling experiments of 18kg/m light rail has been accomplished in Yanshan University Rolling Laboratory. Compared the results of numerical simulation and the experimental data, the roll force from upper-bound method is somewhat greater than experimental data but in general do not exceed them by 20 percent. So, it is reliable and feasible to preset and optimize the parameter of rolling technology according to the upper-bound method.
关键词:
rail rolling;universal mill;upper-bound method;rigid-plastic FEM(finite element method);roll force;experiments
