Mathematical Modelling of Bainite Transformation Kinetics

In this study, the phase transformation behaviour of the carburised layer and the matrix of 23CrNi3Mo steel was comparatively investigated by constructing continuous cooling transformation (CCT) diagram, determining the volume fraction of retained austenite (RA) and plotting dilatometric curves. The results indicated that Austenite formation start temperature (Ac1) and Austenite formation finish temperature (Ac3) of the carburised layer decreased compared to the matrix, and the critical cooling rate (0.05 °C/s) of martensite transformation is significantly lower than that (0.8 °C/s) of the matrix. The main products of phase transformation in both the carburised layer and the matrix were martensite and bainite microstructures. Moreover, an increase in carbon content resulted in the formation of lamellar martensite in the carburised layer, whereas the martensite in the matrix was still lath. Furthermore, the volume fraction of RA in the carburised layer was higher than that in the matrix. Moreover, the bainite transformation kinetics of the 23CrNi3Mo steel matrix during the continuous cooling process indicated that the mian mechanism of bainite transformation of the 23CrNi3Mo steel matrix is two-dimensional growth and one-dimensional growth.

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Effect of pro-eutectoid ferrite on subsequent bainite transformation kinetics simulation

Materials Science and Technology ◽

10.1080/02670836.2019.1569288 ◽

2019 ◽

Vol 35 (4) ◽

pp. 429-436

Author(s):

Xiangjun Chen ◽

Bernard Rolfe ◽

Amir Abdollahpoor ◽

Namin Xiao ◽

Dianzhong Li

Keyword(s):

Transformation Kinetics ◽

Bainite Transformation ◽

Kinetics Simulation

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Bainite transformation kinetics Part 2 Non-uniform distribution of carbon

Materials Science and Technology ◽

10.1179/mst.1992.8.11.994 ◽

1992 ◽

Vol 8 (11) ◽

pp. 994-1003 ◽

Cited By ~ 34

Author(s):

G. I. Rees ◽

H. K. D. H. Bhadeshia

Keyword(s):

Uniform Distribution ◽

Transformation Kinetics ◽

Bainite Transformation

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Study of Phase Transformation of Medium Carbon Steel after Hot Plastic Deformation

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.258.599 ◽

2016 ◽

Vol 258 ◽

pp. 599-602

Author(s):

Rostislav Kawulok ◽

Ivo Schindler ◽

Petr Kawulok ◽

Janusz Dänemark ◽

Petr Opěla ◽

...

Keyword(s):

Plastic Deformation ◽

Phase Transformation ◽

Carbon Steel ◽

Medium Carbon Steel ◽

Transformation Kinetics ◽

Bainite Transformation ◽

Cooling Rates ◽

Hot Plastic Deformation ◽

Medium Carbon ◽

Start Temperature

The CCT and DCCT diagrams of steel C60 (with approx. 0.6 % C) were constructed on the basis of dilatation tests with and/or without an influence of the previous deformation and they were then compared, order to make an evaluation of the influence of the previous deformation on the phase transformation kinetics. For the execution of the experiment, the dilatation module of the plastometer Gleeble 3800 was used. The accuracy of the diagrams was faced with metallographic analyses and measurements. The previous deformation expressly retarded a bainite transformation and slightly accelerated ferrite and pearlite transformations. The martensite start temperature was practically not influenced by the previous deformation; however, the applied deformation caused the creation of the martensite at lower cooling rates.

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Slow Bainite: an Opportunity to Determine the Carbon Content of the Bainitic Ferrite during Growth

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.172-174.111 ◽

2011 ◽

Vol 172-174 ◽

pp. 111-116 ◽

Cited By ~ 4

Author(s):

Francisca García Caballero ◽

Michael K. Miller ◽

Carlos García-Mateo

Keyword(s):

Solid Solution ◽

Carbon Content ◽

Atom Probe Tomography ◽

Early Stage ◽

Bainitic Ferrite ◽

Atom Probe ◽

Transformation Kinetics ◽

Bainite Transformation ◽

Parent Austenite ◽

Kinetics Of

The amount of carbon in solid solution in bainitic ferrite at the early stage of transformation has been directly determined by atom probe tomography at 200 °C, taking advantage of the extremely slow transformation kinetics of a novel nanocrystalline steel. Results demonstrated that the original bainitic ferrite retains much of the carbon content of the parent austenite providing strong evidence that bainite transformation is essentially displacive in nature.

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The Effects of Hot Deformation of Austenite on the Bainite Transformation in a Fe-C-Mn-Si-Cr Steel

Materials Science Forum ◽

10.4028/www.scientific.net/msf.941.486 ◽

2018 ◽

Vol 941 ◽

pp. 486-491

Author(s):

Shang Ping Chen ◽

Radhakanta Rana ◽

Bin Xiao ◽

Arunansu Haldar

Keyword(s):

Strain Rate ◽

Hot Deformation ◽

Tensile Deformation ◽

Deformation Mode ◽

Uniaxial Tensile ◽

Transformation Rate ◽

Compression Tests ◽

Transformation Kinetics ◽

Bainite Transformation ◽

Strain And Strain Rate

The effects of hot deformation conditions in the stable austenite state on the transformation kinetics and morphology of bainite were examined using dilatometry, electron back scatter diffraction (EBSD) and X-ray diffraction (XRD) measurements in a carbide-free bainitic steel with a composition of Fe-0.34C-2Mn-1.5Si-1Cr (in wt.%). Both uniaxial tensile and compression tests were applied to study the effect of the deformation mode. The temperature, strain and strain rate of deformation were varied in the ranges of 820-1000 °C, 0.1-0.6 and 0.001-0.1/s respectively. It has been revealed that hot tensile deformation retards the austenite transformation to lower bainite. The overall transformation kinetics slows down and the final attained amount of bainite decreases after completion of the isothermal transformation at 350 °C. However, hot compression deformation accelerates the bainite transformation, increasing both the bainite transformation rate and the final amount of bainite formed. The total amount of bainite increases with decreasing the strain rate irrespective of the mode of deformation. The effect of the deformation temperature and strain on the bainite transformation is in a complicated manner depending on the deformation mode.

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On Bainite Transformation Kinetics and Mechanism

THERMEC 2006 - Materials Science Forum ◽

10.4028/0-87849-428-6.3018 ◽

2007 ◽

pp. 3018-3023

Author(s):

Si Xin Zhao ◽

Wei Wang ◽

Da Li Mao

Keyword(s):

Kinetics And Mechanism ◽

Transformation Kinetics ◽

Bainite Transformation

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Analytical Description of the Bainite Transformation Kinetics in Steels 300M and D6AC

Materials Science Forum ◽

10.4028/www.scientific.net/msf.907.31 ◽

2017 ◽

Vol 907 ◽

pp. 31-37

Author(s):

Aleksandra A. Kuklina ◽

Mikhail V. Maisuradze ◽

Yury V. Yudin

Keyword(s):

Analytical Description ◽

Analytical Models ◽

Avrami Equation ◽

Ratio Test ◽

Transformation Kinetics ◽

Bainite Transformation ◽

Fisher Ratio ◽

Analytical Approaches ◽

Kinetics Of ◽

Best Fit

The most widely used equation for analytical description of the transformation kinetics of the metastable solid solutions (the steel austenite in particular) is Kolmogorov-Johnson-Mehl-Avrami (KJMA) equation [1]. However the practical analysis of the experimental isothermal bainite transformation kinetics often gives significant deviation from the conventional theory [2]. This problem can be solved by the derivation of an analytical function which would provide the best fit of the experimental results. Two analytical approaches describing the kinetics of bainite transformation in steels 300M and D6AC are proposed. The first one is based on an approximation of the experimental ln (-ln (1-Р)) vs. ln τ dependence by a second order polynomial function. The second approach is based on the solution of the differential equation y(x) = ay’(x)+b, where x= ln τ, y(x) = ln(-ln(1-P)). A comparison between the proposed approaches and Kolmogorov - Johnson - Mehl – Avrami equation is conducted. The adequacy of the two analytical models is estimated using Fisher ratio test.

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