XU Bojun GU Nanju YAN Dianran YIN Fuxing Hebei Institute of Technology
,
Tianjin
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China GU Nanju Division of Heat Treatment
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Hebei Institute of Technology
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Tianjin 300132
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China
金属学报(英文版)
Using a self-made pulse magnetic field heat treatment equipment with low or medium intensi- ty,the tempering process of high speed steel W6Mo5Cr4V2 was investigated.It was found that the secondary hardening process and the transformation of retained austenite for the steel were accelerated by the pulse magnetic field,and the tempering period could be reduced to half of the original.It was shown by the analyses of X-ray and eletron microscopy that the precipitation of carbides becomes more homogeneous and dispersive,and the tetragonality of martensite increases obviousely,which causes the improvement of hardness and red-hardness for the steel.It was confirmed that the service life of tools as centre bits,screw taps and punches for nuts could be increased by 0.4 to 1.4 times by the tempering in magnetic field.
关键词:
pulse magnetic field
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null
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null
C. Jiang
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Y.B. Chen
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B.S. Wu
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Q.L. Jin
金属学报(英文版)
Temperature field numerical simulation about he heat treatment process curve of large turbine rotor is presented. With simulation software Deform3D in according to the heat treatment processing of China First Heavy Machinery, the details of temperature change at the different location of the rotor is to be found. Once knowing the temperature field change, the duplex grain defect long time existed in large forgings can be solved with a quantitative analysis instead of only the qualitative one. Precondition for small metal samples is brought to simulate microstructure and grain size change of large rotor according to the numerical simulation result. Also, consistent feature with real manufacture is showed from the physical experiment, so that the simulation can be used to not only improve the products process but also prevent wasting unnecessary energy and shorten process periods. The rotor quality is controlled thoroughly with plenty of experiments data.
关键词:
temperature field
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null
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null
Applied Surface Science
Anodic oxidation could be employed to produce crystalline titania films on Ti6Al4 V surfaces for inducing apatite formation in simulated body fluid (SBF). In this work, the effect of further heat treatment on the bioactivity of anodic titania films was researched. The surface constitution, morphology, crystal structure and apatite-forming ability of titania films were characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results indicated the apatite formation on the Ti6Al4 V surfaces could be attributed to abundance of Ti-OH groups formed via anodic oxidation, but subsequent heat treatment would decrease the amount of surface hydroxyl (OH) groups and result in the loss of the apatite-forming ability. (C) 2009 Elsevier B.V. All rights reserved.
关键词:
Heat treatment;OH;Anodic oxidation;Bioactivity;apatite-forming ability;metal;oxidation;surface;water
新型炭材料
The influence of heat treatment on the microstructure and mechanical properties of isotropic pyrolytic carbon prepared by chemical vapor deposition was studied by TEM, SEM, XRD, polarized light metallography, laser Raman spectroscopy, microhardness and three-point bend tests. Results show that the interlayer spacing of the pyrolytic carbon decreases and the crystal size increases with increasing heat treatment temperature. At the same time, the microhardness and the elastic modulus decrease with increasing heat treatment temperature. Heat treatment below 2 400 degrees C has no effect on the flexural strength of the isotropic pyrolytic carbon, but its flexural strength. increases after graphitization at 2 600 degrees C. It is observed that the high temperature heat treatment has changed the pore structure, which consequently influences the mechanical properties.
关键词:
isotropic pyrolytic carbon;heat treatment;microstructure;mechanical;property;raman;porosity
自然科学进展﹒国际材料（英文）
Microstructural evolution and micro-hardness of a directionally solidified Ni-base superalloy subjected to shot-peening during cyclic recovery heat treatment was studied. It was found that gamma' dissolved and dislocation annihilation occurred during heating, while gamma' re-precipitated when temperature dropped. Due to the formation of a stable dislocation network at gamma/gamma' interface, full recovery and therefore complete elimination of the surface recrystallization are difficult by the present cyclic recovery heat treatment.
关键词:
recrystallization;superalloy;dislocation;recovery heat treatment;nickel-base superalloy;single-crystal;behavior
Materials Transactions
The heat treatment parameters of AZ64 magnesium alloy have been optimized using thermal analysis, scanning electron microscopy and X-ray diffraction techniques. The thermal analysis result revealed that two precipitation reactions took place during the solidification of AZ64 alloy. Therefore, a two-step solution heat treatment method, instead of traditional solution treatment whose temperature was about 10 degrees C below the solidus temperature, was developed corresponding to the dissolution of two precipitate phases. With comparison to the traditional heat treatment, the two-step treatment method could generate a complete solution effect. During the following aging process, precipitates almost uniformly dispersed throughout the matrix, thus improve the tensile strength of alloy.
关键词:
AZ64 magnesium alloy;thermal analysis;two-step solution treatment;mechanical properties;ductility;strength
P. R. Ding
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D. Y. Ju
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T. Lnouc and E. de Vries( 1) MSC Japan Ltd.
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Osaka
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Japan 2) Saitama Institute of Technology
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Saitama
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Japan 3) Kyoto Universily
,
Kyoto
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Japan 4) MacNeal - Schwendler (E. D. C. ) B. V.
,
Gouda
,
The Netherlands)
金属学报(英文版)
A method to simulate processes of forging and subsequent heat treatment of an axial symmetric rod is formulated in eulerian description and the feasibility is investigated. This method uses finite volume mushes for troching material deformation and an automatically refined facet surface to accurately trace the free surface of the deforming material.In the method,the deforming work piece flows through fixed finite volume meshes using eulerian formulation to describe the conservation laws,Fixed finite volume meshing is particularly suitable for large three-dimensional deformation such as forging because remeshing techniques are not required, which are commonly considered to be the main bottelencek in the ssimulations of large defromation by using the finite element method,By means of this finite volume method, an approach has been developed in the framework of "metallo-thermo-mechanics" to simulate metallic structure, temperature and stress/strain coupled in the heat treatment process.In a first step of simulation, the heat treatment solver is limited in small deformation hypothesis,and un- coupled with forging. The material is considered as elastic-plastic and takes into account of strain, strain rate and temperature effects on the yield stress.Heat generation due to deformation,heat con- duction and thermal stress are considered.Temperature - dependent phase transformation,stress-in- duced phase transformation,latent heat,transformation stress and strain are included.These ap- proaches are implemented into the commerical commercial computer program MSC/SuperForge and a verification example with experimental date is given as comparison.
关键词:
finite volume method
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null
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null
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null
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null
X.G. Li
金属学报(英文版)
The specimens of 304 austenite stainless steel with the hydrogen attack bubbles orcracks were heat treated at 600℃ for 6h. The SEM and TEM observations on thespecimens before and after the heat treatment showed that the bubbles or cracks could behealed completely by heat treatment. The healing of hydrogen attack bubbles or cracksis closely related to heat diffusion of Fe and C atoms in austenite. The driving forceof crack healing results fram the plastic deforming energy Es induced by the growthof hydrogen attack bubbles or cracks. The critical condition of healing of bubbles orcracks is Es ≥ 2γ/r (where γγ is the surface tension, r is the radius of bubbles or halflength of crack). During healing of the hydrogen attack bubbles or cracks, the recovery,polygonization and recrystallization of the sub-grain also occured.
关键词:
stainless steel
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null
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null
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null
LI Donggui J.P.Simpson R.Schenk Dalian Acid Proof Pump Plant
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China. Sulzer Bros.Ltd
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Winterthur
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Switzerland.
材料科学技术（英文）
The effect of heat treatment on the corrosion performance of austenitic-ferritic duplex stain- less steel COR 25 in aqueous solution containing 60%H_3PO_4+4%H_2SO_4+1500 ppm Cl~- at 95℃ was in- vestigated.When the solution temperature was increased from 950℃ to 1230℃,the corrosion resistance increased by two orders of magnitude, as shown by electrochemical measurements,im- mersion tests and direct observation under the scanning electron microscope.The specimens heat treated at solution temperatures of 950℃ and 1030℃ were severely corroded along the phase boundaries;specimens treated at 113C℃ and 1230℃ tended to selective corrosion caused by the dissimilar chromium contents of the aus- tenite and ferrite phases after heat treatment.
关键词:
heat treatment
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null
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null
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null
Corrosion
The goal of the present experiments was to obtain crack heating of hydrogen attack (HA) in low-carbon steel by heat treatment. It was observed by scanning electron microscopy (SEM) that HA cracks experienced different heating effects. The results indicated that HA cracks less than or equal to10 mum in length can be heated completely by cyclic heat treatment between room temperature and 1, 000degreesC. Five cycles totaling 10 h were used. The studies performed showed that crack heating is controlled by diffusion and that the recovery kinetics depend on the plastic deforming energy, E., arising from the growth of HA bubbles or cracks. These findings led to the conclusion that the critical condition for healing of bubbles or cracks is E-S greater than or equal to 2 gamma/r (where gamma is the surface tension and r is the radius of bubbles or the half-length of cracks), provided the atoms of H, C, and Fe can diffuse rapidly.
关键词:
crack;heating;heat treatment;hydrogen attack;low-carbon steel;scanning electron microscopy
