M. Militzer The Centre for Metallurgical Process Engineering
,
University of British Columbia
,
Vancouver
,
BC
,
Canada V6T 1Z4
金属学报(英文版)
The microstructure evolution has been investigated for hot rolling of advanced low carbon steels containing Nb, Ti, V and Cu. The critical processing step to develop the properties of hot rolled steels is cooling after rolling when the austenite-to-ferrite transformation as well as precipitation takes place thereby determining the final mi- crostructure. Thus, the modelling work emphasizes the kinetics of errite formation. Ferrite growth rates can adequately be described by taking into account a solute-drag- like effect of Mn and Nb. The emphasis of the model is to predict the phase transfor- mation kinetics for the industrial practice of accelerated cooling. The ferrite grain size is essentially determined at the early stages of transformation and can be correlated to the trunsformation start temperature. Pcarbides and nitrides of Nb, Ti and V is controlled by Ostwald ripening of these particles. The ageing behaviour can then be described based on the Shercliff-Ashby model for precipitation hardening. The situa- tion is more complex for Cu precipitation where the ageing response is also related to a sequence of different precipitation types.
关键词:
low carbon steal
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null
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null
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null
牛勇
,
李晓华
,
王耀奇
,
侯红亮
,
李淼泉
,
林莺莺
,
李志强
稀有金属材料与工程
利用XRD分析了置氢Ti-6A1-4V合金的相组成,应用Gleeble等温热模拟试验研究了置氢量对Ti-6A1-4V合金高温塑性变形的影响,计算了不同置氢量钛合金的变形激活能.结果表明:随置氢量的增加,Ti-6A1-4V合金β相含量增加,高温塑性变形的流动应力显著降低呈下凹型曲线变化,即存在一个最小值,应力最小值对应的置氢量随变形温度的升高而降低:置氢可以促进高温塑性变形过程动态软化与硬化的平衡;在相同应力水平下,适量的置氢可使变形温度降低50℃,或应变速率提高一个数量级.置氢Ti-6A1-4V合金变形激活能随置氢量增加呈下降趋势,变形由不受扩散机制控制转变为受扩散机制控制.
关键词:
Ti-6A1-4V合金
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置氢
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高温塑性变形
R. V. Safiullin
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R.A. Vasin and F. U. Enikeev Institute for Metals Superplasticity Problems Khalturina
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39
,
Ufa
,
450001
,
Russia
金属学报(英文版)
A method for determining the value of the strain rate sensitivity parameter m, of a thin sheet superplastic material, which is based on the results of constant gas pressure tests, has been developed in this paper. Unlike the conventional procedures the method involved provides the test conditions similar to those occurring during an industrial technological process. Such an approach enables one to estimate reliable the superplas- tic properties of the material under study. Theoretical analysis is based upon use of the standard equations of the membrane theory. The experimental investigations have been carried out for Ti-based alloy VT6 (Ti--6Al-4V). Theoretical predictions show satisfactory agreement with experimental data. The results obtained are compared with those measured by means of standard procedures (constant cross-head velocity experiments and load relaxation tests). It is shown that the use of specimens having reduced gage length (which is less than specimen's width) could lead to considerable errors in experimental estimation of the m value which, in its turn, leads to inaccurate calculating the technological parameters.
关键词:
superplasticity
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null
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null
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null
Surface & Coatings Technology
Ti-6Al-4V alloy with and without boron ion implantation has been tested in stress-controlled tension-zero fatigue conditions. The alloy was implanted at energies of 120 keV and with doses of 2 x 10(17) ions cm-2. A 12% increase in endurance limit was found with implantation. The implanted surface and fracture surface structure, the dislocation arrangement and the concentration profile of boron in implanted layers were examined using scanning electron microscopy, transmission electron microscopy and secondary-ion mass spectroscopy. It was found that boron implantation produced irradiation defects and fine titanium boride precipitates. The implanted layers are obstacles preventing glide dislocations from moving out to the surface; at the same time implanted atoms diffuse into the base metal during fatigue cycling.
关键词:
ion-implantation
C.P. Chou
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S.C. Wang
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C.C. Chang and W.R. Wang 1) Department of Mechanical Engineering
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National Chiao Tung University Hsinchu
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Taiwan 300
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China 2) Materials Research Laboratories
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Industrial Technology Research Institute Chutung
,
Taiwan 310
,
China
金属学报(英文版)
Titanium has been widely used as the implant materials of joint prostheses. This paper simulates the microstructures of the hot forged titanium knee joint component by physical modeling. Ti-6Al-4V ELI were deformed by GLEEBLE 2000 hot deforma- tion simulator in compression mode to determine the hot workability, in the range of 900 to 1100℃, with the strain rates between 0.05 to 5 s~(-1). Test results derived from specimens processed by on-cooling test and on-heating test were compared, thereby estimating the effect due to thermal history. The forging process of Ti-6Al-4V ELI tibial base plate of knee joint prostheses was design based on the workability data obtained.
关键词:
physical modeling
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null
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null
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null
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null
胡季帆
,
张茂森
功能材料
研究了TbMn6-xTxSn6(T=Al,V)新型稀土锰基化合物的居里温度、饱和磁化强度、自旋重取向温度、磁各向异性和成分x的关系.发现磁各向异性场和自旋重取向温度具有类似的成分依赖关系.
关键词:
稀土锰基化合物
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磁性
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研究
