Zhenni ZHOU
金属学报(英文版)
The pearlite transformation in a Mo-containing iron alloy was investigated under 12~T magnetic field. The pearlite transformation was accelerated owing to the application of a strong magnetic field. Pearlite was of degenerated morphology without the presence of a strong magnetic field; but the degeneracy of pearlite is reduced when a strong magnetic field was applied, which may be attributed to the effect of strong magnetic field on faster carbon diffusion and less molybdenum segregation caused by a strong magnetic field.
关键词:
Steels
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Pearlite
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Phase transformation
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Strong magnetic field
P.Parameswaran
材料科学技术（英）
Electron enregy loss spectroscopy (EELS) and energy filtering transmission electron microscopy (EFTEM) investigation on 2.25Cr-1Mo steel was carried out to understand the nature of evolution of secondary carbides. The filtered images obtained from two different ageing treatments indicate that the steel evolves to a more stable carbide namely M23C6 in comparison to M2C. Microchemical information was generated from EELS spectra. Suitable choice for estimating the microchemical state was discussed. To evaluate the behaviour of ageing an elemental ratio of Fe to Cr is employed.
关键词:
Ferritic steels
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Steels
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2.25Cr-1Mo
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steels
,
EFTEM
L.X.Pan
,
L.P.Karjalainen
,
M.C.Somani
材料科学技术（英）
Some observations are reported on the simulation of two thermomechanical routes to produce ultrafine ferrite grain size in steels. One C-Mn grade and Nb, Nb-Ti and Nb-high Ti bearing steels were used in the tests performed on a Gleeble simulator and a laboratory rolling mill. The routes included severe hot deformation of prior grain-refined austenite at the temperature close to Ar3 (DIF) and static recrystallization of fine-grained cold-rolled martensite (SRM). It was observed that the hot deformation induces the formation of ferrite above the Ar3 temperature of the steel, but severe reductions are required for the complete transformation. Strain of 1.2 can result in about 70% of ferrite with the grain size of about 1.4～2 μm in all the studied steels. Similarly, in short annealing of cold-worked martensite, the static recrystallization can also lead to a grain size of about 1.5 μm. The distribution of carbon varies in the microstructures, carbon being in the second phase in the DIF route and in carbide particles in the SRM route, which may have a significant influence on the mechanical properties and the thermal stability of ultrafine grain structure.
关键词:
Ultrafine grain size
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null
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null
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null
