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International Journal of Metallurgical & Materials Engineering Volume 1 (2015), Article ID 1:IJMME-104, 5 pages
http://dx.doi.org/10.15344/2455-2372/2015/104
Research Article
Simulation of Cyclic Transformations in the Intercritical Range of a 5Mn Steel

P.I. Sarafoglou, M.I.T. Tzini and G.N. Haidemenopoulos*

Department of Mechanical Engineering, University of Thessaly, Pedion Areos, 38500 Volos, Greece
Prof. Gregory Haidemenopoulos, University of Thessaly, Pedion Areos, 38500 Volos, Greece; E-mail: hgreg@mie.uth.gr
23 March 2015; 05 May 2015; 07 May 2015
Sarafoglou PI, Tzini MIT, Haidemenopoulos GN (2015) Simulation of Cyclic Transformations in the Intercritical Range of a 5Mn Steel. Int J Metall Mater Eng 1: 104. doi: http://dx.doi.org/10.15344/2455-2372/2015/104

Abstract

Partial cyclic phase transformations α→γ and γ→α triggered by temperature cycling in the intercritical range (α+γ) have been simulated in a medium-Mn steel with composition Fe-0.2C-5Mn. Additional simulations have been performed in Fe-0.2C-0.2Mn and Fe-0.2C steels for comparison. The computational kinetics software DICTRA has been employed for the simulations. All simulations were carried out under local equilibrium conditions. A specially-designed thermal cycle was considered. The position and the velocity of the austenite-ferrite interface were monitored during temperature cycling. Cyclic behavior is characterized by hysteresis loop formation. No loop formation was observed for the plain carbon steel. The inverse transformation, where the interface proceeds in a direction opposite to the temperature change has been identified for the Fe-0.2C-5Mn steel. The duration of the inverse transformation stage is larger at the minimum temperature of the cycle while the phase fraction formed during the inverse transformation is larger at the maximum temperature of the cycle. When the cyclic transformation takes place at a time before the final phase equilibrium in the isothermal curve, the transformation is characterized as inverse during the whole cooling part of the cycle. A stagnant stage where the transformation is very sluggish was observed during the cyclic transformations for the steels investigated. The study of cyclic transformations provides insight into the kinetics of phase transformations in medium-Mn steels.Partial cyclic phase transformations α→γ and γ→α triggered by temperature cycling in the intercritical range (α+γ) have been simulated in a medium-Mn steel with composition Fe-0.2C-5Mn. Additional simulations have been performed in Fe-0.2C-0.2Mn and Fe-0.2C steels for comparison. The computational kinetics software DICTRA has been employed for the simulations. All simulations were carried out under local equilibrium conditions. A specially-designed thermal cycle was considered. The position and the velocity of the austenite-ferrite interface were monitored during temperature cycling. Cyclic behavior is characterized by hysteresis loop formation. No loop formation was observed for the plain carbon steel. The inverse transformation, where the interface proceeds in a direction opposite to the temperature change has been identified for the Fe-0.2C-5Mn steel. The duration of the inverse transformation stage is larger at the minimum temperature of the cycle while the phase fraction formed during the inverse transformation is larger at the maximum temperature of the cycle. When the cyclic transformation takes place at a time before the final phase equilibrium in the isothermal curve, the transformation is characterized as inverse during the whole cooling part of the cycle. A stagnant stage where the transformation is very sluggish was observed during the cyclic transformations for the steels investigated. The study of cyclic transformations provides insight into the kinetics of phase transformations in medium-Mn steels.