材料期刊网

THE FAILURE MECHANISM OF REVERSE SHAPE MEMORY EFFECT IN A Cu-BASE ALLOY

C.M Li , G.X. Dong , S.T- Dai , and D. Y Chen (Tsinghua University Beijing 100084 , China)J Yin and D.X. Hu (Shanghai No.5 Steel Works , Shanghai 200940 , China)

金属学报(英文版)

The interior structural evolution accompanying reverse shape memory effect (RSMEin a Cu-Zn-Al alloy was studied by means of transmission electron microscopy. It was found that RSME is closely related to bainitic transformation in this alloy during the isothermal reaction at moderate temperatures. At a given temperature and a certain external constraint stress, the shape memory effect depends mainly on the aging time.During the early stage, the shape memory effect enhances with the increase of reactiotn time. Then it will decrease gradually apon further aging. If the alloy is overaged, the stacking faults of bainite will disappear gradually by the motion of partial dislocations through which long range diffusion of solute atoms takes place, giving rise to the deterioration of RSME. When all the bainite transforms to α phase, RSME will lose completely.

关键词: reverse shape memory effect , null , null , null

R&D STATUS ON INTERMETALLICS IN CHINA

CHEN Guoliang(State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 , China)SHI Changxu (Academia Sinica , Beijing 100864 , China)

金属学报(英文版)

This paper briefiy introduces the R&D of intermetallics in China. R&D on intermetallics in a national scale in China began near ten years ago. The investigation in past years focused on the fundamental research and materials development. A significant progress has been made. Various components that made of Ti3Al Ni3Al, TiAl and Fe3Al have been successfully manufactured Some of them have been evaluted. It is expected that some intermetallic alloys will be produced in an industrial scale in the near future.

关键词: :intermetallic alloys , null , null , null

X70管线钢J1d和K1a与V型缺口Ak关系研究

朱杰武 , 柳永宁 , 许雁 , 冯耀荣

机械工程材料 doi:10.3969/j.issn.1000-3738.2005.06.007

在不同温度下测试了X70管线钢动态断裂韧度K1d、J1d和止裂韧度K1a以及夏氏V型缺口冲击韧度Ak,对三者的关系进行了分析.结果表明:温度和加载速率都对断裂韧度产生影响;加载速率变化引起的韧-脆断裂转变具有热激活特征,在热激活分析基础上,在应力强度因子速率K=15 MPa·m1/2s-1条件下,得出断裂韧度、止裂韧度和冲击韧度三者的关系:Ak=4.84×106T-2.8K1d(或K1a).可以用小试样Ak数据计算得到K1d和K1a.

关键词: 管线钢 , 断裂韧度 , 止裂韧度 , 韧-脆断裂转变

Key R&D activities for development of new types of wrought magnesium alloys in China

Transactions of Nonferrous Metals Society of China

Many researchers in China are actively engaged in the development of new types of wrought magnesium alloys with low cost or with high-performances and novel plastic processing technologies. The research activities are funded primarily through four government-supported programs: the Key Technologies R&D Program of China, the National Basic Research Program of China, the National High-tech R&D Program of China, and the National Natural Science Foundation of China. The key R&D activities for the development of new wrought magnesium alloys in China are reviewed, and typical properties of some new alloys are summarized. More attentions are paid to high-strength wrought magnesium alloys and high-plasticity wrought magnesium alloys. Some novel plastic processing technologies, emerging in recent years, which aim to control deformation texture and to improve plasticity and formability especially at room temperature, are also introduced.

关键词: wrought magnesium alloy;microstructure;properties;alloy designing;plastic deformation;research projects;y-zr alloys;mechanical-properties;mg-4y-4sm-0.5zr alloy;grain-refinement;rare-earth;microstructure;gd;phase;temperature;evolution

RESEARCH AND DEVELOPMENT OF NEW SUPERALLOY REMELTING PROCES

W.Xie

金属学报(英文版)

Shanghai No.5 Steel Co., Ltd. has recently introduced a set of 5-ton protective atmosphere electroslag remelting furnace and a set of lO-ton helium-cooling vacuum arc remelting furnace,both of them are the first one of its kind in China. With these equipment, remelting processes about alloy GH4169, GH2132 and GH738 were researched, the process of producing alloy GH4169 by VIM+ VAR + ESR triplex-process was developed, and their effects were discussed.

关键词: superalloy , null , null

Stress Distribution and Cleavage Analysis in a 16MnNiMo5 Bainitic Steel X-ray Diffraction and Multiscale Polycrystalline Modelling

Raphaë , l Pesci , Karim Inal , Renaud Masson

材料科学技术（英文）

Many tensile tests have been realized on the 16MnNiMo5 bainitic pressure vessel steel at low temperatures [-196℃,-60℃. The damaging processes (ductile/fragile) are observed with a scanning electron microscope (SEM), while X-ray diffraction (XRD) is used to determine the internal/residual stresses within the ferritic phase during loading (in-situ) and after unloading: stress states are lower in ferrite than in the bulk material due to cementite particles, the difference never exceeding 150 MPa. A polycrystalline modelling with a two-level homogenisation is also developed concurrently with the experimental characterization. It correctly reproduces the stress distribution in each phase, the intergranular strain heterogeneity as well as the macroscopic fracture stress and strain in relation to temperature, considering a constant number of grains (7%) reaching an experimentally identified crystallographic criterion of cleavage.

关键词: Internal stresses , null , null , null

Change in Carbon Dioxide (CO2) Emissions From Energy Use in China′s Iron and Steel Industry

SUN Wenqiang , CAI Jiuju , MAO Hujun , GUAN Duojiao

钢铁研究学报(英文版)

As the largest energy consuming manufacturing sector and one of the most important sources of carbon dioxide (CO2) emissions, the China′s iron and steel industry has paid attention to the study of changing trend and influencing factors of CO2 emissions from energy use. The logarithmic mean Divisia index (LMDI) technique is used to decompose total change in CO2 emissions into four factors: emission factor effect, energy structure effect, energy consumption effect, and steel production effect. The results show that the steel production effect is the major factor which is responsible for the rise in CO2 emissions; whereas the energy consumption effect contributes most to the reduction in CO2 emissions. And the emission factor effect makes a weak negative contribution to the increase of CO2 emissions. To find out the detailed relationship between change in energy consumption or steel production and change in CO2 emissions, the correlation equations are also proposed.

关键词: CO2 emissions , energy use , LMDI technique , steel production , energy consumption

5d电子掺杂的SmFe_(1-x)Ir_xAsO铁基超导体的合成及物性

陈永亮 , 崔雅静 , 杨烨 , 王磊 , 李仪成 , 张勇 , 赵勇

低温物理学报

通过在SmFeAsO中Fe位上掺入5d过渡金属Ir,得到了一种新的铁基超导体SmFe_(1-x)Ir_xAsO,当x=0.05时,样品表现出超导电性,超导转变温度为8K,当x=0. 15时,超导转变温度达到最大值17. 3K X射线衍射结果表明所有样品均属四方ZrCuSiAs-type结构,SEM结果表明SmFe_(1-x)Ir_xAsO样品具有片层状形貌特征,随着Ir掺杂量的增大,晶格参数a增大而c减小,结合EDX数据,表明Ir掺人了SmFeAsO晶格当中.

关键词: 铁基超导体 , ZrCuSiAs结构

Cavitation erosion behavior of Cr-Mn-N stainless steels in. comparison with 0Cr13Ni5Mo stainless steel

Wear

The cavitation erosion (CE) behavior of two kinds of Cr-Mn-N stainless steels was investigated by means of an ultrasonic vibration processor and compared with that of 0Cr13Ni5Mo stainless steel, commonly used material for hydraulic turbines in China. The eroded surfaces after different CE duration were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Roughness (R-a) of the eroded surfaces was calculated from the measured profiles after different CE duration, and microhardness of cross-sections of the tested materials was also measured to indicate work-hardening ability. The results show that the CE resistance of austenitic single phase or austenite-ferrite duplex phase Cr-Mn-N steels is higher than that of the 0Cr13Ni5Mo martensitic stainless steel, which is mainly attributed to their high work-hardening ability. Different from 0Cr13Ni5Mo stainless steel, the cracks initiating in the eroded austenite of Cr-Mn-N stainless steels propagate nearly parallelly rather than normally to the surface, which is also beneficial to the resistance to CE. Low ferrite content is also found to be beneficial to improving the resistance to CE of duplex phase Cr-Mn-N stainless steels. It is supposed that in the case of Cr-Mn-N stainless steels the cavitation impingement energy could be absorbed and transferred into the inside of materials by the "forming and transferring" mode of the high hardness layer. Developing steel with high work-hardening ability and low ferrite volume content is possibly an important method to design steel with high CE resistance. (C) 2003 Elsevier Science B.V. All rights reserved.

关键词: Cr-Mn-N stainless steels;cavitation erosion;ferrite content;mechanism;work-hardening;hydraulic turbines;resistance;duplex;alloys

Relationship between electrochemical characteristics and SCC of X70 pipeline steel in an acidic soil simulated solution

Zhiyong LIU

金属学报(英文版) doi:10.1016/S1006-7191(08)60071-X

Stress corrosion cracking (SCC) of X70 pipeline steel in simulated solution of the acidic soil in Yingtan in China was investigated using slow strain rate test (SSRT), SEM and potentiodynamic polarization technique. Experiment results indicate that X70 steel is highly susceptible to SCC as applied potential reduces, which is manifested in loss of toughness and brittle fracture. Constant polarization current can detect the occurrence of SCC. The lower the polarization current is the sooner stress corrosion cracking occurs. The SCC mechanisms are different at varying potentials. When potential is higher than open circuit potential, anodic process controls SCC, whereas when potential is far lower than open circuit potential, cathodic process controls SCC, and between these two potential regions, a combined electrochemical process controls the SCC. Stress or strain has a synergistic effect with electrochemical reactions to accelerate the cathodic hydrogen evolution process, which makes the X70 pipeline steel to be more susceptible to SCC.

关键词: X70 steel , null , null , null