Lower bainite with midrib in hypereutectoid steels

Okamoto, Hisaki; Oka, Mariko

doi:10.1007/bf02665309

Cited by 59 publications

(34 citation statements)

References 4 publications

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“…It is also reported that bainite decomposition of austenite at martensite/austenite interfaces progressively took place during isothermal aging even above 200 C in hypereutectoid steels. 23) Therefore, the results shown in Fig. 8 that the block size for Z200 is larger than that of ZRT are not so unreasonable.…”

Section: Strengthening Mechanismmentioning

confidence: 87%

Effect of Martensitizing Temperature on Creep Strength of Modified 9Cr Steel

et al. 2011

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A modified 9Cr-1Mo steel was cooled to a temperature between the M s point and room temperature from the normalizing temperature and then directly heated to the tempering temperature. It was found that the time to rupture at 650 and 700 C of the steel heat-treated by the new heat treatment increased 2-3 times longer than that of the steel conventionally normalized and tempered. The microstructure of the improved steel was tempered martensite and the size of martensite blocks was larger than for the conventional heat treatment. The hardness of the improved steel was fully recovered after tempering. This strengthening is not caused by fresh martensite, but caused by the refining of M 23 C 6 and V(C,N) particles in addition to the increase in the martesite block size, where M denotes metallic elements.

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Section: Strengthening Mechanismmentioning

confidence: 87%

Effect of Martensitizing Temperature on Creep Strength of Modified 9Cr Steel

et al. 2011

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“…The authors have previously reported 4) that no lattice transition regime exists in the bainite/austenite interface observed in Fe-2Si-1.4C alloys as seen in martensite/ austenite interface, and that diffusional transformation-like features such as misfit dislocations corresponding to the angle between interface and {111} terrace surface, and shear transformation-like characteristics such as high density dislocations inside bainite coexist. Furthermore, we have reported that bainite transformation mechanism combining shear transformation and diffusion transformation can consistently explain various structural observations claiming evidence of either diffusion or shear transformation, 2,3,[5][6][7][8] by presuming alloy composition and processing temperature causes difference in whether shear transformation or diffusion transformation dominates. In particular, if upper bainite and lower bainite of the same alloy composition is compared, lower bainite forming at lower temperatures show more shear transformation-like characteristics.…”

Section: Discussionmentioning

confidence: 99%

“…2, and the (0001) plane of " phase and {010} plane of plane is not parallel but is at an angle of 70. 5 . At the center of Fig.…”

Section: " Phase (Hcp)mentioning

confidence: 99%

“…This system is favorable for interface observation because fine particles of carbides such as Fe 3 C do not precipitate, and plate-like structure formation can be observed. 5) Observations showed that lattice transformation region as seen in martensite/austenite interfaces does not exist in bainite/austenite interfaces, that misfit dislocations exist corresponding to the angle between the interface and {111} terrace plane, and that high concentration of dislocations exist inside bainite, along with other features.…”

Section: Introductionmentioning

confidence: 98%

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Isothermal fcc/hcp Transformation in Fe-Si-C-Alloy Thermally Treated at Lower Bainitic Transformation Temperature

2009

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High resolution transmission electron microscopic observations have revealed that isothermal fcc () to hcp (") transformation accompanies the bainitic transformation from austenite to bcc () bainite in an Fe-2Si-1.4C (mass%) alloy heated at lower bainitic transformation temperature of 570 K. The " plates are formed at the ledges of bainite/ austenite interfaces. The unit volume of the " phase with respect to that of the austenite increases by as much as 16% when the " plate has grown from 4 nm to 100 nm in thickness, probably due to enhancement of interstitial carbon. There is no visible stacking fault in the " phases. These experimental results are interpreted by the concept of bainitic transformation both with shear-type and diffusion-type nature.

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“…4,8,9) As seen in these examples, fcc to bcc may be either diffusion driven or shear driven depending on the alloy system or transformation temperature, however the following characteristics are experimental evidence that are commonly observed.…”

Section: )mentioning

confidence: 99%

Atomic Arrangement of Interphase Boundary between Bainite and Austenite in Fe-Si-C Alloy

2010

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Atomic arrangement of bainite/austenite interface was examined by high resolution electron microscopy in a Fe-2Si-1.4C alloy. Lattice transition region with an intermediate lattice structure between two phases, which is a characteristic feature of shear-type deformation, was not observed either between upper bainite and austenite or between lower bainite and austenite. However, high density dislocations existed inside upper and lower bainites, which may be introduced as a result of lattice invariant shear deformation. Based on these experimental facts, the shear deformation assisted-diffusional transformation model was proposed for the bainitic transformation.

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Lower bainite with midrib in hypereutectoid steels

Cited by 59 publications

References 4 publications

Effect of Martensitizing Temperature on Creep Strength of Modified 9Cr Steel

Effect of Martensitizing Temperature on Creep Strength of Modified 9Cr Steel

Isothermal fcc/hcp Transformation in Fe-Si-C-Alloy Thermally Treated at Lower Bainitic Transformation Temperature

Atomic Arrangement of Interphase Boundary between Bainite and Austenite in Fe-Si-C Alloy

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