H. R. Hou
,
Q. Y. Liu
,
Q. A. Chen and H. Dong Division of Structural Materials
,
Central Iron & Steel Research Institute
,
Beijing 100081
,
China
金属学报(英文版)
Heavy deformation and controlled cooling is one of the most effective effective ways for grain refinement in HSIA steels. In this paper, experimental specimens are prepared with a commercial linepipe steel grade X65, and the chemical compositions are (wt% ): Fe-0.094C-1.42Mn-0. 29Si-0. 045Nb-0. 008Ti. After heavy deformation with 80% reduction in non-recrystallization range of austenite, and at controlled cooling rates from 2K/s to 64K/s, the grain sizes vary from 9.55μm to 1.06μm.It is shown by the results that a linear relationship still remains between the yield strength and reciprocal of square root of ferrite grain size as grain size is refined to 1m.The ultra-fine grains might be dynam- ically formed through the deformation-induced transformation when reduction is large enough.The grain sizes decrease when the cooling rates increase.When the cooling rates increase over 10K/s, the grain sizes are rarely changed. The particles distribute on grain boundaries, sub-grain boundaries, deformed bands and within the ferrite grains.
关键词:
microalloyed steel
,
null
,
null
,
null
Materials Science & Engineering C-Biomimetic Materials Sensors and Systems
The terminology of materials study inspired by biological systems or phenomena is analyzed at first. It is pointed that the term "bio-inspired" may be better than the terms "bionic" or "biomimetic", since the former is relatively easy to be accepted. The new trends of bio-inspired study of structural materials are analyzed in short. Some progress in bio-inspired design and processing of materials in this institute (IMRCAS) are summarized briefly in this talk, such as biomimetic design of worst bonding interface for composites; dumbell-like whiskers simulating animal bone; fractal tree reinforcement by mimicry of branched roots in soil; etc. The possibility of modification and recovery of materials by nonequilibrium bio-inspired treatment are further explored, including the nonequilibrium process under transient heating, dissipative structure and self-organization process of open system, inspiration by living process, influence of high intensive electropulsing on the working Life of materials, a possible way of fatigue recovery of materials and the healing effect of electropulsing in metals. Some tentative practice in biomaterial modification are also studied such as the reformed bamboo reinforced aluminium laminates, etc. A discussion on the methodology of bio-inspired study of materials consists briefly in the last part of the talk. (C) 2000 Elsevier Science S.A. All rights reserved.
关键词:
bio-inspired;bionic;biomimetic;structural materials;composites
Journal of Applied Physics
The dependence of yield strength, uniform elongation, and toughness on grain size in metallic structural materials was discussed. The toughness is defined as the product of yield strength and uniform elongation. The yield strength versus grain size can be well described by the Hall-Petch relation; however, the uniform elongation versus grain size is not well understood yet. A simple model involving the densities of geometrically necessary dislocations and statistically stored dislocations was proposed to estimate the uniform elongation versus grain size. Existing data for low carbon steels and aluminum indicate that, in the grain size less than 1 mu m, the materials usually exhibit high strength and low uniform elongation and, in the grain size greater than 10 mu m, the materials usually exhibit low strength and high elongation; in either case the toughness is low. However, in the grain size of several micrometers, the toughness is the highest. It is suggested that we should pay more attention to develop the metallic materials with grain size of several micrometers for structural applications. (c) 2007 American Institute of Physics.
关键词:
nanocrystalline copper;nanostructured metal;steels;deformation;ductility;law
G.Q. Zhang
金属学报(英文版)
The status of research, development of superalloys and materials processing & fabrication technologies for aero-engine applications in China Aviation Industry, with an emphasis on recent achievements at BIAM including directionally solidified and single crystal superalloys for blade and vane applications, wrought superalloys for aero-engine disks and rings, and powder metallurgy (PM) superalloys for high performance disk applications were described. It was also reviewed the development of new class of high temperature structural materials, such as structural intermetallics, and advanced material processing technologies including rapid solidification, spray forming and so on. The trends of research and development of the above mentioned superalloys and processing technologies are outlined. Cast, wrought and PM superalloys are the workhorse materials for the hot section of current aero-engines. New high temperature materials and advanced processing technologies have been and will be the subject of study. It is speculated that high performance, high purity and low cost superalloys and technologies will play key roles in aero-engines.
关键词:
superalloy
,
null
,
null
L.F Li
,
YY Li
,
O. Sbaizeroand S. Meriani(Cryoguic Laboratory Chinese Academy of Sciences
,
Beijing 100080
,
China )(Institute of Metal Research
,
Chinese Academy of Sciences
,
Shenyang 110015
,
China)(Materials Engineering Department
,
University of Triesty
,
Italy)
金属学报(英文版)
The use of zirconia-based ceramic materials as smpport materidls for superconducting magnets and in cryopenic engineeriny generally has been considered. The relationship between compsition and mechanical properties at cryogenic temperature has also been investigated.
关键词:
structural material
,
null
,
null
,
null
Current Opinion in Solid State & Materials Science
First-principles method based on the electronic structure theory is one of the most promising approaches of computational materials design. Although only a few of mechanical properties (e.g., ideal strength and elastic constants) are accessible directly by first-principles calculations, such methods may predict the complex mechanical properties by extracting appropriate calculable parameters (e.g., the ratio of bulk modulus to shear modulus, the formation energies of and interaction energies between lattice defects) and adopting proper models (e.g., Peierls-Nabarro model for dislocation core). In this paper, we briefly review recent first-principles investigations of mechanical properties of structural materials, covering topics of ideal strength, elastic constants, and lattice defects. Some of the major recent advances, such as the application of coherent potential approximation coupled first-principles methods (accurate enough for the calculating of the elastic constants of random alloys with complex compositions), the appreciation of the importance of low C, I-C, 2 to the,super properties' of BCC-Ti based alloys, and the relationship between solute-vacancy interaction and creep resistance, etc., are highlighted. (c) 2006 Elsevier Ltd. All rights reserved.
关键词:
first-principles methods;mechanical properties;ideal strength;elastic;modulus;lattice defects;density-functional-theory;grain-boundary cohesion;ab-initio;calculation;intermetallic compounds;disordered alloys;ideal strength;1st principles;segregation;embrittlement;iron
International Journal of Non-Equilibrium Processing
New nanocomposite Al(93.3-x)Fe(4.3)V(0.7)Si(1.7)Mm(x) (x = 0.5, 1, 3) materials have been made by melt-quenching. The nanophase structural features and the component configurations have been investigated by X-ray diffraction, transmission electron microscopy and Mossbauer effect spectroscopy. The results show significant lattice contraction in alpha-Al with increasing Mm content, and there are different nanometer-sized particles corresponding to alpha-Al-13(Fe,V)(3)Si and Al(8)Fe(4)Mm mixed phase for x = 0.5, only Al(8)Fe(4)Mm for x = 1 and Al(20)Fe(5)Mm for x = 3. The inherent Fe atomic environment in the Al(20)Fe(5)Mm quasicrystalline phase is characterized by a distribution of electric quadrupole splitting, which is shown to be well described by a Gaussian shape. The lattice contraction is believed to be correlated with the variation of component configurations in alpha-Al solid solution.
关键词:
Al-based;nanocomposite;quasicrystal;lattice contraction;melt;spinning;nanocrystalline materials;alloys;mossbauer;fe
Acta Chimica Sinica
Passive film formed on 304 stainless steel in 2.5 mol/L H2SO4 solution by using alternating voltage (A. V.) passivation have been investigated by measuring capacitance and photoelectrochemical parameters. The investigation of the effect of measure frequency on the slope of Mott-Schottky curve has been carried out. The photoelectrochemical measurements were consistent with the capacitance measurement. Analysis of the experimental results showed that the passive film formed 304 stainless steel by using A. V. passivation exhibits semiconducting properties. Using the simple model of semiconductor rather than the multi-donor level model can explain satisfactorily the semiconducting behavior of the film formed on 304 stainless steel by using A.V. passivation.
关键词:
A. V. passivation;passive film;semiconducting properties;stainless;steel;model;electrodes
郭秀辉
钢铁研究
为保证莱钢Q275D热轧H型钢极限规格的-20℃冲击功值满足GB/T 700-2006要求,采用Nb微合金化结合再结晶控轧工艺试制了极限规格H400 mm× 200 mm×8 mm×13 mm的Q275D热轧H型钢.结果表明:试制产品的上屈服强度为360～368 MPa,抗拉强度为480～500 MPa,伸长率为32.5 ％～33.0％,平均冲击功为154～233 J,各项性能指标满足标准要求.
关键词:
热轧H型钢
,
再结晶控制轧制
,
Nb微合金化
