材料期刊网

ON THE SWERVING OF STRENGTH CURVE FOR STEEL 20Cr11MoVNbNB

FU Changpu ZHA NG Jinwang Shaanxi Mechanical Engineering Institute , Xi′an.ChinaPAN Jingda D U Wenfeng Beijing Heavy Electric Machine Works , Beijing , China

金属学报(英文版)

Study was made on the swerving of the curves of strength and hardness vs L-M parameter P=T(20+lgt)for steel 20Crl 1MoVNbNB aged at 550.600 and 650℃ for 0—5000 h,T being aging temperature in K and taging time in h.The swerving seems to be due to:(1)the coarsening of the mean size of principal precipitate M_(23)C_6,(2)the precipitation of Laves phase MoFe_2;(3)the decrease of Mo content in matrix and(4)the recovery and recrystallization of the matrix phase.

关键词: L-M parameter , null , null , null , null

FIELD-THEORY AT FINITE-TEMPERATURE AND ETA-XI-SPACETIME

Science in China Series a-Mathematics Physics Astronomy

The relation between eta-xi spacetime and the field theories at finite temperature is discussed.

关键词:

Influence of electric parameters on MAO of AZ91D magnesium alloy using alternative square-wave power source

Transactions of Nonferrous Metals Society of China

Micro-arc oxidation (MAO) process was carried out on AZ91D alloy in alkaline borate solution using an alternative square-wave power source with different parameters. The effects of voltage, frequency and duty cycle on the coatings were investigated by orthogonal experiment. It is found that the thickness of coatings increases with the increase of voltage and duty cycle, but decreases with the increase of frequency. The structure and morphology of the coatings also depend on voltage, frequency and duty cycle. The coatings become more porous and crack with increasing voltage and duty cycle. The coating is thin and transparent when the voltage is lower than 120 V. The corrosion resistances of different coatings were evaluated by polarization curves and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl (mass fraction) solution. When the optimized values of voltage, frequency and duty cycle are 140 V, 2 000 Hz and 0.4, respectively, the anodic coating shows the best corrosion resistance.

关键词: AZ91D magnesium alloy;micro-arc oxidation (MAO);alternative;square-wave;duty cycle;applied voltage;frequency;plasma electrolytic oxidation;mg-al alloys;corrosion behavior;anodic;films;coatings;additives;performance;resistance;phase

FRACTURE MECHANICS ANALYSIS OF THERMAL STRAIN FATIGUE LIFE FOR THE SINTERING MACHINE PALLET

LI Zhenzi and LI Ming (Department of Architectnre Engineering , Central South University of Technology , Changsha 410083 , China)LIAO Fuchang (Shenzhen School of Technology , Shenzhen 518029 , China)Manuscript received 10 August 1995 , in revised form 12 April 1996

金属学报(英文版)

In recent years elastic-plastic fracture mechanics has developed rapidly and is widely used to solve various engineering problems. The application of elastic-plastic fracture mechanics on the pallet of sintering machine is approached in detail for the first time in the present study. The theoretical results were compared with the actual data determined from sintering machine pallet. Results show that good agreement was achieved between the method suggested by the author and the actual data. The basis of determining design of the sintering machine pallet in iron and steel engineering has been provided and it will result in great economic benefits.

关键词: : pallet , null , null , null

EFFECT OF REMOVING HYDROGEN FROM HEAVY RAIL STEEL BLOOMS BY STACK COOLING IN PANZHIHUA IRON AND STEEL COMPANY

XIAN Aiping LI Peiji CHEN Wenxiu WANG Yikang Institute of Metal Research , Academia Sinica , Shenyang , ChinaCHEN Renvi MEI Dongsheng Panzhihua Institute of Iron and Steel Research , Ministry of Metallurgical Industry , Panzhihua , China associate professor , Institute of Metal Research , Academia Sinica , Shenyang 110015 , China

金属学报(英文版)

The determination of dffusible hydrogen in U71Mn heavy rail steel,and hydrogen diffusivity as well as the hydrogen distribution in the cross section of blooms with stack cooling were stu- died.The results showed that,most of the hydrogen in blooms of heavv rail steel is diffusible, the hydrogen diffusivity in U71Mn rail steel blooms at room temperature is(0.85—1.02)× 10~(-6)cm~2/s,after stack cooling,the hydrogen content in bloom will decrease greatly which is helpful to form the flake-free phenomenon in the heavy rail produced by Panzhihua Iron and Steel Company.

关键词: rail steel , null , null , null

Effect of liquid phase on densification in electric-discharge compaction

Journal of Materials Science

The effect of liquid phase on densification in electric-discharge compaction (EDC) was explored in the present work. The temperature at contact area of particles in EDC was estimated from random packing model incorporated with electric current distributions. Consolidation of cemented carbide and tungsten heavy alloys was conducted under varying current densities. WC-11Co/Fe/WC-11Co sandwich powder compacts were designed to investigate the effect of liquid phase flow. It is found that the densification occurred only when liquid phase formed, and relative density increased with the increasing of liquid phase volume. In the case of WC-11Co powders, the faceted grain evolution occurred but the significant grain growth was hardly observed, which meant the densification was mainly induced by particle rearrangement. The depth of liquid penetration of Fe in WC-11Co/Fe/WC-11Co sandwich compact also agreed with that caused by particle rearrangement processing. The possible effects of electric current on densification were also discussed.

关键词: powder;metal;consolidation;growth;field

Fe-C-Xi多元合金系γ→α转变中PLE/NPLE转变温度的计算

盛广 , 杨志刚

金属学报 doi:10.3321/j.issn:0412-1961.2007.04.003

根据局部平衡模型,Fe-C-Xi合金系铁素体生长模式可以分为合金元素Xi扩散控制的再分配局域平衡模式(partition local equilibrium,PLE)和C元素扩散控制的不分配局部平衡模式(no partition local equilibrium,NPLE).在基本热力学模型的基础上,建立了简便计算Fe-C-Xi合金系PLE/NPLE转变温度的方法.代入合金原始成分,即可准确计算这一成分对应的PLE/NPLE转变温度.应用这一方法计算了多种Fe-C-Xi合金系的PLE/NPLE转变温度.

关键词: Fe-C-Xi合金系 , 铁素体 , 热力学 , PLE/NPLE转变温度

Fe-∑Xi-C合金系超组元模型Zener两参数的修正

彭宁琦 , 唐广波 , 刘正东 , 吴秀月

金属学报 doi:10.3321/j.issn:0412-1961.2009.03.013

根据Aaronson提出的超组元模型,借助Ae3的实验数据,提出了修正的置换型元素Xi(Xi=Si,Mn,Ni,Co,Mo,Al,Cu,Cr)的Zener两参数,修正中考虑了合金元素间的交互作用.修正后的超组元模型的预测精度明显改善:Ae3计算值与实验值的标准差为10.8℃,与Thermo-Calc计算值的标准差为2.35℃;Ae1计算值与实验值的标准差为6.8℃.按照马氏体相变热力学的计算方法,采用经修正的参数计算了马氏体相变开始温度Ms,提高了Ms点的预测精度,计算值与实验值的标准差为25.3℃.

关键词: 相变 , 热力学 , 超组元模型 , 相变平衡温度

U薄膜制备方法

吕学超 , 任大鹏 , 汪小琳

稀有金属材料与工程

探讨了U薄膜的制备方法.主要介绍了机械抛光、电解抛光、机械轧制、磁控溅射沉积、离子束辅助沉积和聚焦离子束方法等,涉及了精细U薄膜的制备要求.同时,简要介绍了防止U薄膜氧化的后处理手段.

关键词: U薄膜 , 制备方法 , U薄膜抗氧化处理

Simulation and prediction of the alkalinity in sintering process based on grey least support vector machine

SONG Qiang

钢铁研究学报(英文版)

Prediction of the alkalinity is a difficult problem during the process of sintering .Whether the level of he alkalinity of it is successful or not direct relates to the quality of sinter.By now,there isn’t a very good method due to the high complexity ,high non-linear, strong coupling, high delay-time and etc.A grey support vector machine model was proposed on the basis of the models.The fluctuation of data sequence is weakened by the grey theory and the support vector machine is capable of processing non-linear adaptable information, and the grey support vector machine is a combination of those advantages. The results reveal, the alkalinity of sinter can be accurately predicted through this model by reference to small sample and information. It was concluded that the grey support vector machine model is effective with the advantages of high precision, less samples required and simple calculation.

关键词: alkalinity of sinter;grey least support vector machine;prediction;the sintering process;grey model.