Topic
Bainite
About: Bainite is a research topic. Over the lifetime, 9520 publications have been published within this topic receiving 145305 citations.
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TL;DR: In this article, the authors used X-ray diffraction to study shape-memory alloys of composition Ti-(49.73 −51.05 at %) subjected to quenching and thermomechanical treatment (TMT) by the scheme “cold deformation (e = 0.3 −1.9) + postdeformation annealing (200 −500°C) to provide different defectness of the parent B2 austenite.
Abstract: X-ray diffraction has been used to study shape-memory alloys of composition Ti-(49.73–51.05 at %) Ni subjected to quenching and thermomechanical treatment (TMT) by the scheme “cold deformation (e = 0.3–1.9) + postdeformation annealing (200–500°C) to provide different defectness of the parent B2 austenite. For the quenched alloys, the concentration dependences of the lattice parameters of the B19′ martensite, maximum lattice strain upon martensitic transformation, the crystallographic orientation of the lattice in single crystals, and the reserve of recoverable strain in polycrystals have been determined. The lattice parameters of martensite formed from polygonized, i.e., nanosubgranular, or from nanocrystalline austenite differ from the corresponding parameters of quenched martensite formed from recrystallized austenite, and their difference increases with increasing defectness of the parent-austenite lattice. An increase in the defectness of the austenite lattice is accompanied by a decrease in the reserve of recoverable strain. The deformation of the existing martensite or the formation of stress-assisted martensite under the anisotropic action of external stresses changes the interplanar spacing and the thermal expansion coefficient in different crystallographic directions but does not affect the averaged lattice parameters near the M
s-M
f interval and the reserve of recoverable strain.
50 citations
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TL;DR: In this article, the effect of finishing rolling temperature (FRT) relative to the non-recrystallization temperature (TNR) was studied for industrial scale direct-quenched steel coils using laboratory simulations.
50 citations
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TL;DR: In this paper, a kinetic theory for the formation of bainite in steels where the precipitation of carbides is suppressed is suppressed. The theory is based on the mechanism of transformation.
Abstract: Steels with a mixed microstructure of allotriomorphic ferrite, bainitic ferrite, retained austenite and martensite have potentially good combinations of high strength and formability. This work describes a kinetic theory for the formation of bainite in steels where the precipitation of carbides is suppressed. The theory is based on the mechanism of transformation. It includes, for example, a nucleation model based on the Magee/Olson/Cohen theory for martensite, growth by a diffusionless mechanism in which sheaves of bainite form by the repeated nucleation of sub-units. These latter platelets grow to a size limited by plastic accommodation of the shape deformation. The theory is compared against experimental data.
50 citations
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TL;DR: In this article, the authors examined the structures produced in a Nb-microalloyed steel by oil quenching after intercritical anneals at 760 and 810 °C.
Abstract: The structures produced in a Nb-microalloyed steel by oil quenching after intercritical anneals at 760 and 810 °C have been examined by light and transmission electron microscopy. After both anneals, the periphery of the austenite pool transforms on cooling to ferrite in the same orientation as the ferrite retained during intercritical annealing. Thus the ferrite forms by an epitaxial growth mechanism without the formation of a new interface or grain boundary. The new ferrite is precipitate-free in contrast to the retained ferrite which develops a very dense precipitate dispersion during intercritical annealing. In the carbonenriched interior of the austenite pool beyond the epitaxial ferrite only martensite forms in specimens annealed at 760 °C but various mixtures of ferrite and cementite form in specimens annealed at 810 °C. The latter structures include lamellar pearlite, a degenerate pearlite, and cementite interphase precipitation. All Nb is in solution in the austenite formed at 810 °C, and therefore the low hardenability of the specimens annealed at that temperature is best explained by the effect of low austenite carbon content.
50 citations
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10 Dec 2013-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, an ultra-low carbon Ti-containing microalloyed steel has been thermo-mechanically controlled rolled and water-quenched and microstructural characterization of the samples finish rolled in the temperature range of 750-850°C revealed the presence of polygonal ferrite, quasi-polygonal Ferrite, acicular ferrite and granular bainite.
Abstract: An ultra-low carbon Ti-containing microalloyed steel has been thermo-mechanically controlled rolled and water-quenched. Microstructural characterization of the samples finish rolled in the temperature range of 750–850 °C revealed the presence of polygonal ferrite, quasi-polygonal ferrite, acicular ferrite and granular bainite. Micro-texture study showed the dominance of random texture and cube orientation at higher deformation temperatures, whilst, α-fiber and γ-fiber components intensified with the decrease in finish rolling temperature. Characteristic ferrite-bainite microstructure with fine ferrite grain size (
50 citations