Correlation of martensitic and bainitic transformations in carbon and alloy steels

Счастливцев, В. М.; Мирзаев, Д. А.; Baev, A. I.; Karzunov, S. E.; Yakovleva, I. L.

doi:10.1007/bf00778640

Cited by 5 publications

(14 citation statements)

References 1 publication

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“…Within the approach under consideration, the instability of austenite with respect to γ →α +θ decomposition develops stepwise with the temperature decrease. Existence of the threshold temperature of autocatalysis is consistent with the available experimental data [46,47]. For example, according to Ref.…”

Section: Discussionsupporting

confidence: 86%

“…For example, according to Ref. [47] the pearlite nucleation rate (in contrast to the growth rate) is close to zero at [46] where a narrower temperature interval with the close to zero nucleation rate was observed.…”

Section: Discussionmentioning

confidence: 99%

“…We use the dissolution and mixing energies of carbon close to those known from experimental data and ab initio calculations: α ε FM =0.9 [37,47,48], α ε PM =0.9 [48], γ ε PM =0.3 [50,51], γ ε FM = -0.4 [28,48], α v =6 [26], γ v =1.5 [26,51] (in eV/at). The estimations of γ v are vary greatly from 1 to 3 eV/at; the values α ε PM , γ ε FM are known only from ab initio calculations; and the difference between ab initio and experimental estimations of α ε FM , γ ε PM is about 0.2eV/at.…”

Section: Appendix: Details Of Parameterizationmentioning

confidence: 99%

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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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Section: Discussionsupporting

confidence: 86%

Section: Discussionmentioning

confidence: 99%

Section: Appendix: Details Of Parameterizationmentioning

confidence: 99%

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Autocatalytic Mechanism of Pearlite Transformation in Steel

2017

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“…The question what factors ensure the stability of the front of colony is remained open to discussion [61][62][63][64][65]. 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].…”

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

confidence: 99%

“…Despite a broad distribution of numerous new materials, steel known from ancient times remains the main structural material of our civilization [1], due to high availability of its main components (Fe and C) and diversity of properties reached by a realization of various (meso)structural states [2][3][4][5][6]. One can control the structural state of steel due to a rich phase diagram of iron with several structural transformations at cooling from moderately high temperatures ( δ → γ → α); the presence of carbon adds carbide phases, cementite Fe3C being the most important one.…”

Section: Introductionmentioning

confidence: 99%

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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Optimization of Chemical Composition and Heat Treatment of High-Carbon Iron Alloys with 14% Chromium and 3% Vanadium

Koryagin

Okishev

Созыкина

2016

MSF

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A series of iron alloys for wear applications containing 14 %Cr, 3 %V and 1.5 to 4.2 %C is investigated in as-cast and quenched condition. In almost all alloys carbide phases were hexagonal M7C3 and cubic VC carbides. Critical points of the alloys were determined dilatometrically; cooling from 1000 °C at a rate of 0.4 K/s results in diffusional decomposition of austenite, and at the rate of 15 K/s (air) - in martensitic transformation. The experiments on modifying the alloys with 0.1–0.5 %Ce showed that cerium refines the structure at the concentrations not exceeding 0.3 %Ce. Strength and wear resistance reach maximum at ~ 0.2–0.3 %Ce, and alloy hardness is not significantly affected. Heat treated (quench hardened) alloys show typical behaviour of high-carbon ledeburitic alloys, viz. hardness as a function of quenching temperature reaches maximum when the amount of retained austenite is increased. The greatest hardness of 68.5 HRC is achieved in the 3.5 %C alloy, which also has the highest wear resistance. A method of phase composition and hardness calculation for high-carbon alloys based on thermodynamic description of ternary system Fe–Cr–C is presented; the calculation results align with the experimental data.

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Correlation of martensitic and bainitic transformations in carbon and alloy steels

Cited by 5 publications

References 1 publication

Autocatalytic Mechanism of Pearlite Transformation in Steel

Autocatalytic Mechanism of Pearlite Transformation in Steel

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

Optimization of Chemical Composition and Heat Treatment of High-Carbon Iron Alloys with 14% Chromium and 3% Vanadium

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