Ferrite formation in Fe-C alloys during austenite decomposition under non-equilibrium interface conditions

Krielaart, G.P.; Sietsma, Jilt; Zwaag, Sybrand van der

doi:10.1016/s0921-5093(97)00365-1

Cited by 135 publications

(77 citation statements)

References 11 publications

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“…The observation of the current study is aligned with the previous reported results that ferrite formation in stainless steels is different among those with dissimilar compositions [2][3][4][5]10,11]. In the study, we found that ferrite formation in steel ingots was highly relevant to the mushy zone temperature.…”

Section: Discussionsupporting

confidence: 92%

Novel formation of Ferrite in Ingot of 0Cr17Ni4Cu4Nb Stainless Steel

Han

Dessau³

et al. 2018

ChemEngineering

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Abstract:The ferrite body is the origin of crack and corrosion initiation of steels. Distribution and density of ferrite in seven steel ingots were examined by light optical microscopy and computational modeling, in the study, to explore the correlation of ferrite formation to chemical composition and the mushy zone temperature in ingot forming. The central segregation phenomenon in ferrite distribution was observed in all the examined steel specimens, except 0Cr17Ni4Cu4Nb stainless steel. No significant difference was found in the distribution and density of ferrite among zones of the surface, 1 2 radius, and core in neither the risers nor tails of 0Cr17Ni4Cu4Nb ingots. Additionally, fewer ferrites were found in 0Cr17Ni4Cu4Nb compared to other examined steels. The difference of ferrite formation in 0Cr17Ni4Cu4Nb elicited a debate on the traditional models explicating ferrite formation. Considering the compelling advantages in mechanical strength, plasticity, and corrosion resistance, further investigation on the unusual ferrite formation in 0Cr17Ni4Cu4Nb would help understand the mechanism to improve steel quality. In summary, we observed that ferrite formation in steel was correlated with the mushy zone temperature. The advantages of 0Crl7Ni4Cu4Nb in corrosion resistance and mechanical stability could be the result of fewer ferrites being formed and distributed in a scattered manner in the microstructure of the steel.

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Section: Discussionsupporting

confidence: 92%

Novel formation of Ferrite in Ingot of 0Cr17Ni4Cu4Nb Stainless Steel

Han

Dessau³

et al. 2018

ChemEngineering

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“…The value for the pre-factor of the interface mobility expression M 0 is pre-defined to match the phase-field simulations and is close to the experimental value determined by Krielaart and coworkers. [31] It should be noted that there are many values of M 0 reported in literature. Hillert and Ho¨glund [40] reviewed these values and confirmed that the value reported in Reference 31 was consistent with the experimental measurements for Fe-X (X = Mn, Co or Ni) alloys containing low amounts of carbon.…”

Section: Computational Proceduresmentioning

confidence: 99%

“…where M 0 is a constant and Q M = 140 kJ mol À1 [31] is the activation energy for atomic motion. It should be noted that M 0 in Eq.…”

Section: Ferrite Growthmentioning

confidence: 99%

Analysis of the Grain Size Evolution for Ferrite Formation in Fe-C-Mn Steels Using a 3D Model Under a Mixed-Mode Interface Condition

Fang

Mecozzi

Brück

et al. 2017

Metall Mater Trans A

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A 3D model has been developed to predict the average ferrite grain size and grain size distribution for an austenite-to-ferrite phase transformation during continuous cooling of an Fe-C-Mn steel. Using a Voronoi construction to represent the austenite grains, the ferrite is assumed to nucleate at the grain corners and to grow as spheres. Classical nucleation theory is used to estimate the density of ferrite nuclei. By assuming a negligible partition of manganese, the moving ferrite-austenite interface is treated with a mixed-mode model in which the soft impingement of the carbon diffusion fields is considered. The ferrite volume fraction, the average ferrite grain size, and the ferrite grain size distribution are derived as a function of temperature. The results of the present model are compared with those of a published phase-field model simulating the ferritic microstructure evolution during linear cooling of an Fe-0.10C-0.49Mn (wt pct) steel. It turns out that the present model can adequately reproduce the phase-field modeling results as well as the experimental dilatometry data. The model presented here provides a versatile tool to analyze the evolution of the ferrite grain size distribution at low computational costs.

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“…The percentages of austenite transformed to different phases (ferrite, pearlite, bainite) have been charted in continuous cooling transformation (CCT) diagrams, where the evolution of the fraction transformed to ferrite suggests that this can be predicted by an Avrami type law. [1][2][3][4] Dilatometry is one of the classic techniques, along with differential thermal analysis and quantitative analysis of microstructures, most commonly used to determine the start and end of phase transformations in steels.…”

Section: Introductionmentioning

confidence: 99%

Modelling of Phase Transformation Kinetics by Correction of Dilatometry Results for a Ferritic Nb-microalloyed Steel

2003

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Using the dilatometry technique, g→a transformation kinetics has been determined at different cooling rates in a steel with low carbon and low niobium contents (0.09 and 0.017 mass% respectively). First of all the real and the conventional transformation temperatures of the steel were determined. The real start temperature for proeutectoid ferrite formation (AЈ r3 ) corresponds to the point where the dilatometric curve starts to diverge from the straight during cooling. The conventional start and finish temperatures for proeutectoid ferrite formation (A r3 and A r1 ) are given by two points close to the minimum and the first maximum of the curve, respectively. The real start and finish eutectoid transformation temperatures -(AЈ r1 ) s and (AЈ r1 ) f -correspond to the second point of inflection and a point close to the second relative maximum of the curve, respectively. Carbon enrichment of the remaining austenite, as the transformation to ferrite advances, is corrected taking into account the dependence on the carbon content of the atomic volume of austenite. On the other hand, the dilatometric data have also been corrected with regard to the different expansion coefficients of austenite and ferrite. In this way it has been seen that the lever-rule method applied to the dilatometric curve is useful for determining transformation temperatures, but not for determining transformation kinetics, since the amount of proeutectoid ferrite calculated with this method was up to 10 % greater than the real amount measured with an image analyser. Finally a model based on Avrami's law has been developed for the real g→a transformation kinetics.

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Ferrite formation in Fe-C alloys during austenite decomposition under non-equilibrium interface conditions

Cited by 135 publications

References 11 publications

Novel formation of Ferrite in Ingot of 0Cr17Ni4Cu4Nb Stainless Steel

Novel formation of Ferrite in Ingot of 0Cr17Ni4Cu4Nb Stainless Steel

Analysis of the Grain Size Evolution for Ferrite Formation in Fe-C-Mn Steels Using a 3D Model Under a Mixed-Mode Interface Condition

Modelling of Phase Transformation Kinetics by Correction of Dilatometry Results for a Ferritic Nb-microalloyed Steel

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