Deviations from cooperative growth mode during eutectoid transformation: Mechanisms of polycrystalline eutectoid evolution in Fe–C steels

Ankit, Kumar; Mukherjee, Rabibrata; Nestler, Britta

doi:10.1016/j.actamat.2015.06.050

Cited by 25 publications

(15 citation statements)

References 16 publications

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“…The nucleation of globular pearlite, also known as Divorced Eutectoid Transformation (DET), attracts an essential interest [71][72][73][74][75]. This state is usually produced by the heating of the existing lamellar pearlite above the temperature Teutec until the cementite is almost completely dissolved, and then the cooling below the temperature Teutec is carried out.…”

Section: Kinetics Of Pearlite Transformation Globular and Lamellar Smentioning

confidence: 99%

“…The two competing mechanisms of lamellae multiplication by lateral replication [3,53,69] and splitting of existing lamellae [70] have been proposed. In addition, the reasons for the transition from lamellar to globular pearlite structure with increasing temperature is a matter of considerable interest [71][72][73][74][75]. There is no theory to explain the appearance of pearlite type colonies under realistic parameters.…”

Section: Current Understanding Of Phase Transformations In Iron and S...mentioning

confidence: 99%

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Towards the ab initio based theory of phase transformations in iron and steel

Razumov

Gornostyrev

Katsnelson

2017

Phys. Metals Metallogr.

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Despite of the appearance of numerous new materials, the iron based alloys and steels continue to play an essential role in modern technology. The properties of a steel are determined by its structural state (ferrite, cementite, pearlite, bainite, martensite, and their combination) that is formed under thermal treatment as a result of the shear lattice reconstruction γ (fcc) → α (bcc) and carbon diffusion redistribution. We present a review on a recent progress in the development of a quantitative theory of the phase transformations and microstructure formation in steel that is based on an ab initio parameterization of the Ginzburg-Landau free energy functional. The results of computer modeling describe the regular change of transformation scenario under cooling from ferritic (nucleation and diffusion-controlled growth of the α phase) to martensitic (the shear lattice instability γ → α). It has been shown that the increase in short-range magnetic order with decreasing the temperature plays a key role in the change of transformation scenarios. Phase-field modeling in the framework of a discussed approach demonstrates the typical transformation patterns.

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Section: Kinetics Of Pearlite Transformation Globular and Lamellar Smentioning

confidence: 99%

Section: Current Understanding Of Phase Transformations In Iron and S...mentioning

confidence: 99%

Towards the ab initio based theory of phase transformations in iron and steel

Razumov

Gornostyrev

Katsnelson

2017

Phys. Metals Metallogr.

View full text Add to dashboard Cite

show abstract

“…Besides, the mechanism of lamellae multiplication by replication [1,14] or splitting [15], which plays an important role in PT is still under discussion. Also, moving factors of the transition from lamellar to globular pearlite structure with increasing temperature is currently not well understood [16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Autocatalytic Mechanism of Pearlite Transformation in Steel

2017

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A model of pearlite colony formation in carbon steels with ab-initio parameterization is proposed. The model describes the process of decomposition of austenite and cementite formation through a metastable intermediate structure by taking into account the increase of the magnetic order under the cooling. Autocatalytic mechanism of pearlite colony formation and the conditions for its implementation have been analyzed. We demonstrate that pearlite with lamellar structure is formed by autocatalytic mechanism when thermodynamic equilibrium between the initial phase (austenite) and the products of its decomposition (cementite and ferrite) does not take place. By using model expression for free energy with first-principles parameterization we find conditions of formation of both lamellar and globular structures, in agreement with experiment. The transformation diagram is suggested and different scenarios in the kinetics of decomposition are investigated by phase field simulations. 64.60.My, 75.50.Bb

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“…DET means that when the hypereutectoid steel is heated to Ac1∼Accm, the carbides fail to dissolve completely and exist on the austenite matrix, then the temperature drops below Ac1, these carbides grow as nucleus, completing the spheroidization [7]. Some researchers [8,9] have investigated that the heat treatment based on the principle of DET can obtain fine and evenly distributed spherical carbides in hypereutectoid steel. Silva and Asadi [10][11][12][13] also mentioned that plastic deformation can make the lamellar pearlite broken into spherical carbides.…”

Section: Introductionmentioning

confidence: 99%

Obtaining ultrafine spheroidized carbides by combining warm deformation with divorced eutectoid transformation in GCr15 bearing steel

Qian¹,

Wang²,

Pan³

et al. 2020

Mater. Res. Express

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In this work, the ultrafine spheroidized carbides were obtained by combining warm deformation with the divorced eutectoid transformation (DET) in GCr15 bearing steel. The results show that the temperature range of DET is approximately 730°C to 700°C at a cooling rate of 0.05°C s −1 . It is also found that excellent spheroidized microstructure can be obtained and less deformation resistance can be generated when the deformation is carried out at 720°C with a strain rate of 0.5 s −1 . This result could be ascribed to the fact that deformation provides the driving force for transformation, dynamic recrystallization (DRX) and reduced dislocation density through the coordination of warm deformation and DET. This suggests that the deformation at the initial temperature is more favorable to the spheroidization than that at the intermediate temperature of DET. In addition, it is also proved that the warm rolling forming in the actual production line can shorten the spheroidization time from at least 10 h to 2 h and obtain ultrafine spheroidized carbides with the roundness close to 1. This research may provide a novel pathway to obtain good spheroidization effect with less energy conservation.

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Deviations from cooperative growth mode during eutectoid transformation: Mechanisms of polycrystalline eutectoid evolution in Fe–C steels

Cited by 25 publications

References 16 publications

Towards the ab initio based theory of phase transformations in iron and steel

Towards the ab initio based theory of phase transformations in iron and steel

Autocatalytic Mechanism of Pearlite Transformation in Steel

Obtaining ultrafine spheroidized carbides by combining warm deformation with divorced eutectoid transformation in GCr15 bearing steel

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