Microstructure of Granular Bainite

Josefsson, B.; Andrén, Hans-Olof

doi:10.1051/jphyscol:1988651

Cited by 19 publications

(14 citation statements)

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“…Based on its morphology, the bainite formed in this temperature range is sometimes called granular bainite. [29,30] In the comprehensive article by Steven and Haynes [27] in which they investigated many British Standards (B.S.) En steels, this incomplete transformation effect was already noted and was quantified to some extent.…”

Section: Resultsmentioning

confidence: 99%

Modeling Start Curves of Bainite Formation

Bohemen

2009

Metall Mater Trans A

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It is demonstrated that calculations with a physically based model give an accurate description of the start curve of bainite formation in a wide range of steels. The temperature dependence of the overall kinetics, which determines the characteristic C shape of the start curve, is controlled by both the undercooling below the start temperature (T h À T) and an effective activation energy Q b . A systematic analysis of the model parameters extracted from the best fits of published time-temperature-transformation (TTT) data reveals a material-independent relationship, which means that the activation energy is in accordance with known details of the dislocationbased nucleation model of bainite. It is shown that the C shape of the start curve can be determined for a given alloying content using an empirical relationship derived for Q b and, in combination with the material-independent relationship, the kinetics of bainite can be predicted at all temperature levels.

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Section: Resultsmentioning

confidence: 99%

Modeling Start Curves of Bainite Formation

Bohemen

2009

Metall Mater Trans A

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“…During this gap, it can be inferred that the shear train caused by bainite transformation was partially released. Regarding GB, an unusual type of bainite due to the absence of cementite [16], boundary dislocations are not accumulated because of its ferritic matrix with diffusional transformation mode [29]. Finally, some results reported in previous studies were confirmed, e.g., lower dislocation density in bainite that transformed earlier than martensite [30].…”

Section: Determination Of Strain Distribution and Dislocation Densitymentioning

confidence: 53%

“…In Figure 2c, GB was obtained when the specimen was cooled at 0.05 • C/s. GB is indeed characterized by the absence of carbides and by the presence of isolated martensite-austenite (M-A) constituents [16]. M-A islands appear in grey and are distributed in the ferritic matrix that is dark in the SEM image shown.…”

Section: Morphologic Featuresmentioning

confidence: 99%

Morphological and Crystallographic Characteristics of α Structure in a Low-Carbon Iron–Nickel Alloy

et al. 2018

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The features of α (body-centered cubic) structures were investigated in a low-carbon multicomponent alloy from morphological and crystallographic perspectives. In addition to apparent features of granular bainite and lamellar martensite, a morphological similarity can be found between lath martensite and lath bainite. Therefore, it is of interest to explore possible discrepancies between lath martensite and lath bainite from a crystallographic perspective. These microstructures were obtained by various cooling rates (i.e., water quenching, 5 °C/s, and 0.05 °C/s) and then were characterized by a combination of scanning electron microscopy and electron backscattered diffraction techniques. It is shown that: (1) Lath martensite (LM) formed in the samples that were water-quenched, and a mixture of LM and lath bainite (LB) and granular bainite (GB) formed in the samples cooled at rates of 5 °C/s and 0.05 °C/s, respectively; (2) A Kurdjumov-Sachs relationship was mostly found in as-quenched martensite, while a Greninger-Troiano relationship represented the orientation relationship of LB and GB; (3) As the cooling rate decreased, the dislocation densities in corresponding microstructures were reduced, while the tendency of variant grouping was enhanced.

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“…Granular bainite is an equiaxed bainitic ferrite structure with discrete islands of MA constituent. Granular bainite is formed due to slow cooling and high silicon content [17]. High Si prevents the cementite forming, resulting in formation of blocky ferrite with MA phase.…”

Section: Microstructural Analysismentioning

confidence: 99%

Characterization of magnetically impelled arc butt welded T11 tubes for high pressure applications

et al. 2015

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Magnetically impelled arc butt (MIAB) welding is a pressure welding process used for joining of pipes and tubes with an external magnetic field affecting arc rotation along the tube circumference. In this work, MIAB welding of low alloy steel (T11) tubes were carried out to study the microstructural changes occurring in thermo-mechanically affected zone (TMAZ). To qualify the process for the welding applications where pressure could be up to 300 bar, the MIAB welds are studied with variations of arc current and arc rotation time. It is found that TMAZ shows higher hardness than that in base metal and displays higher weld tensile strength and ductility due to bainitic transformation. The effect of arc current on the weld interface is also detailed and is found to be defect free at higher values of arc currents. The results reveal that MIAB welded samples exhibits good structural property correlation for high pressure applications with an added benefit of enhanced productivity at lower cost. The study will enable the use of MIAB welding for high pressure applications in power and defence sectors.

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Microstructure of Granular Bainite

Cited by 19 publications

References 0 publications

Modeling Start Curves of Bainite Formation

Modeling Start Curves of Bainite Formation

Morphological and Crystallographic Characteristics of α Structure in a Low-Carbon Iron–Nickel Alloy

Characterization of magnetically impelled arc butt welded T11 tubes for high pressure applications

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