Effect of Boron on the Relative Interfacial Tension of Gamma Iron

Adair, Attwell M.; Spretnak, J. W.; Speiser, R.

doi:10.1007/bf03377507

Cited by 2 publications

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“…The literature [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] contains abundant reports related to the mechanism by which boron affects the formation of microstructures in steel; however, studies that consider the effects of both the thermodynamics and kinetics of boron segregation at the austenite grain boundary on the nucleation and the growth of ferrite from austenite are few. Shibata et al studied the influence of boron segregated at the grain boundary on the hardenability of steels 17) using the alphaparticle track etching (ATE) method.…”

Section: Introductionmentioning

confidence: 99%

Kinetic Model of the γ to α Phase Transformation at Grain Boundaries in Boron-bearing Low-alloy Steel

2014

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The effect of boron on the nucleation and growth of ferrite at austenite grain boundaries is examined theoretically under the assumption that the junction of 4-austenite grain boundaries (i.e., the 4-grain junctions) are the dominant nucleation sites of ferrite. Boron segregates to the austenite grain boundaries and reduces the grain-boundary energy; it thereby retards ferrite nucleation at the grain boundary. The retardation is expressed as a decrease in nucleation density due to an increase in the critical activation energy for nucleation, and the calculated value of the fraction of active nucleation sites is in satisfactory agreement with the experimental results. The reduction of the austenite grain-boundary energy, which we obtained by applying the Gibbs isotherm for adsorption to the boron segregation, is of the same order of magnitude as the reduction is deduced from the results of calculations for a decrease in the nucleation density based on experimental results. The growth of ferrite was calculated using DICTRA, which yielded both the volume fraction and the grain size of transformed ferrite as functions of time; the results agreed with the experimental results. This agreement suggests that the influence of boron on the growth rate is negligible. However, the increase in the size of the diffusion cell due to the addition of boron is considered to be the main reason for the slightly larger grain size of ferrite compared with that in boron-free steel; this result is also in good agreement with experimental observations.

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Section: Introductionmentioning

confidence: 99%

Kinetic Model of the γ to α Phase Transformation at Grain Boundaries in Boron-bearing Low-alloy Steel

2014

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Kinetic Model of ^|^gamma; to ^|^alpha; Phase Transformation at Grain Boundaries in B-Bearing Low Alloy Steel

Yoshida¹,

Ushioda²,

Abe³

et al. 2012

Tetsu-to-Hagane

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緒言低合金鋼にThe effect of Boron (B) on nucleation and growth of ferrite from austenite grain boundaries is examined theoretically assuming the junction of 4-austenite grain boundaries as dominant nucleation sites of ferrite. B segregates to the austenite grain boundaries and reduces the grain boundary energy and thereby retards the ferrite nucleation at the grain boundary. The retardation is expressed as a decrease of nucleation frequency due to an increase of activation energy for nucleation and the calculated value of the fraction of active nucleation sites is in satisfactory agreed with experimental results. The reduction of the austenite grain boundary energy, obtained by applying the Gibbs isotherm for adsorption to the B segregation, is of the same order of as the one which is deduced from results of calculation for decrease in the nucleation frequency based on experimental result. The growth of ferrite is calculated using DICTRA yielding both the volume fraction and the grain size of transformed ferrite as a function of time, which agreed with the experimental results. This suggests the slight influence of B on growth rate. However, the increase of the diffusion cell size due to B addition is considered to be the main reason for the subtle larger grain size of ferrite as compared with B-free steel, which is in good accordance with the experimental fact.

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Effect of Boron on the Relative Interfacial Tension of Gamma Iron

Cited by 2 publications

References 0 publications

Kinetic Model of the γ to α Phase Transformation at Grain Boundaries in Boron-bearing Low-alloy Steel

Kinetic Model of the γ to α Phase Transformation at Grain Boundaries in Boron-bearing Low-alloy Steel

Kinetic Model of ^|^gamma; to ^|^alpha; Phase Transformation at Grain Boundaries in B-Bearing Low Alloy Steel

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