SU Hang
,
PAN Tao
,
LI Li
,
YANG Caifu
,
CUI Yinhui
,
JI Huaizhong
钢铁研究学报(英文版)
By combining thermomechanical coupling finite element analysis with the characteristics of phase transformation [continuous cooling transformation (CCT) curve], the thermal fatigue behavior of train wheel steel under high speed and heavy load conditions was analyzed. The influence of different materials on the formation of the phase transformation zone of the wheel tread was discussed. The result showed that the peak temperature of wheel/track friction zone could be higher than the austenitizing temperature for braking. The depth of the austenitized region could reach a point of 09 mm beneath the wheel tread surface. The supercooled austenite is transformed to a hard and brittle martensite layer during the following rapid cooling process, which may lead to cracking and then spalling on the wheel tread surface. The decrease in carbon contents of the train wheel steel helps inhibit the formation of martensite by increasing the austenitizing temperature of the train wheel steel. When the carbon contents decrease from 07% to 04%, the Ac3 of the wheel steel is increased by 45 ℃, and the thickness of the martensite layer is decreased by 30%, which is helpful in reducing the thermal cycling fatigue of the train wheel tread such as spalling.
关键词:
train wheel steel;thermal cycling fatigue;friction;martensite transformation;thermomechanical coupling
H.P. Chen and Z.J. Deng (State Key Lab. for Mechanical Behavior of Materials
,
Xi'an Jiaotong University
,
Xi'an 710049
,
China)
金属学报(英文版)
The effect of specimen thinkness on JR resistance curve has been investigated using low and middle strength steels. As the J dominance regime is reached, the initial J-integral values, J(i), are definite even if the elastic component Ji(e) and plastic component Ji(p)vary with the thinkness of specimen. The wider the specimen width, the larger the Ji(e)/Ji and the smaller the Ji(p)/Ji. The crack propagation resistance, dJR/da and dJp/da, decreases, while dJe/da increases linearly with increasing specimen thinness.Based on the above experimental results, an empirical formula dJ/da = α+β. B is given, which can be used to evaluate the safety of practical structural components.A modified J-integral is presented, upon which a new view is Put forward that the increase in crack growth resistance is induced mainly by the increase in the plastic J-integral component with the crack propagation,
关键词:
: fracture mechanics
,
null
,
null
,
null
张淑佳
,
卢炎麟
,
任立义
,
洪起超
金属学报
对20 g钢高温断裂韧性随加载速率的变化规律进行了实验研究.在400℃和500℃下,分别测量了几种加载速率下20 g钢的Ji值.实验结果表明:Ji值随应变速率的增大而有较大幅度的降低;在同一应变速率下,400℃时的Ji值小于500℃时的Ji值;400℃时裂纹扩展比500℃时更快.因此,当温度在400℃附近时更应注意避免超载.
关键词:
断裂韧性
,
null
,
null
周兰花
,
陶东平
,
曾富洪
稀有金属
doi:10.3969/j.issn.0258-7076.2011.04.011
在求解分子相互作用体积模型(MIVM)中的分子对位能参数B(ij),B(ji)时,为避免出现计算超量问题,基于遗传算法,提出了一种新算法--多个体参与交叉遗传算法,并给出了新算法的实现方案.在新算法中,采用了轮盘选种法与优秀个体保存、多个体参与交叉和多点变异等策略;选择B(ij),B(ji)个体时,按照适应度函数值愈大,个体被选中的概率愈大的原则,选择二元合金溶液中一组元活度的计算值与实验测定值之间偏差(σ)建立的适应度函数f(x)最大为优化目标.采用Matlab软件编制新算法下的B(ij),B(ji)计算程序,并分别求算了Cd-Bi,Cd-Pb,Cd-Sn,Bi-Pb,Bi-Sn,Pb-Sn等6组二元合金溶液在773 K下合金溶液的参数B(ij),B(ji)优化值.由B(ij),B(ji)计算优化值和其他一些资料数据,使用MIVM进一步预测773 K下Cd-Bi-Pb,Cd-Bi-Sn,Cd-Pb-Sn,Cd-Bi-Pb-Sn多元合金溶液中组元Cd的活度,模型预测值与实验测定值之间的相对误差低于4.6%,偏差低于0.022,两者吻合很好.结果表明,所提出的多个体参与交叉遗传算法为求解MIVM中的参数B(ij),B(ji)提供了一种有力工具,从而也能提高MIVM对多元合金溶液中组元活度的预测效果.
关键词:
MIVM模型
,
分子对位能参数Bij
,
Bji
,
遗传算法
,
活度
Jun Gong
材料科学技术（英文）
Aluminum doped zinc oxide (AZO) thin films were prepared by DC magnetron sputtering at low substrate temperature. A coaxial solenoid coil was placed near the magnetron target to enhance the plasma density (Ji). The enhanced plasma density improved significantly the bulk resistivity (ρ) and its homogeneity in spatial distribution of AZO films. X-ray diffraction (XRD) analysis revealed that the increased Ji had influenced the crystallinity, stress relaxation and other material properties. The AZO films deposited in low plasma density (LPD) mode showed marked variation in ρ (ranging from ~6.5×10-2 to 1.9×10-3 Ω·cm), whereas those deposited in high plasma density (HPD) mode showed a better homogeneity of films resistivity (ranging from ~1.3×10-3 to 3.3×10-3 Ω·cm) at different substrate positions. The average visible transmittance in the wavelength range of 500−800 nm was over 80%, irrespective of the deposition conditions. The atomic force microscopy (AFM) surface morphology showed that AZO films deposited in HPD mode were smoother than that in LPD mode. The high plasma density produced by the coaxial solenoid coil improved the electrical property, surface morphology and the homogeneity in spatial distribution of AZO films deposited at low substrate temperature.
关键词:
Sputtering
吴令
,
姜周华
,
龚伟
,
梁连科
金属学报
利用遗传神经网络对正规溶液模型组元交互作用能进行了改进, 使之更接近实际溶液活度模型, 并将其应用于
MnO--SiO2及CaO--Al2O3二元渣系的组元活度计算. 由于实际溶液的性质不同于正规溶液,
在模型对交互作用能
Ω Mn-Si和ΩSi-Mn的计算时发现, Ωij不仅是温度和组成的函数,
而且在相同的温度和组
成时, Ωij≠Ωji. 通过将该模型的计算结果与大量文献数据进行对比研究,
发现该模型具有很强的非线性拟合能力, 能准确地预报实际溶液组元活度值.
关键词:
炉渣
,
Regular solution model
,
activity
,
NN
,
GA
杨艳琴
,
张宏忠
,
王明花
膜科学与技术
doi:10.3969/j.issn.1007-8924.2008.06.009
采用了一种新颖的改性(Fenton处理)PVDF基体材料的方法,以提高膜的润湿性和耐污染性,并对改性机理做了探讨.结果表明,经Fenton处理后制得的膜亲水性得到了提高,纯水通量由34.6 L/(m2·h)提高到52.3 L/(m2.h),膜表面水接触角由75°降为62.5°,黏附功由91.64 mN/m提高到106.42 mN/m.同时,膜的截留性能也稍有上升,膜的Ji/J0由48.8%提高到69.3%;红外图谱进一步表明,经改性后的膜材料内部接上了丙烯酸(AAc)单体.
关键词:
Fenton试剂
,
聚偏氟乙烯(PVDF)
,
改性
,
膜
