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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Martensite to austenite reversion in a high-Mn steel: Partitioning-dependent two-stage kinetics revealed by atom probe tomography, in-situ magnetic measurements and simulation

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Souza Filho, I. R. [1, 2] ; da Silva, A. Kwiatkowski [1] ; Sandim, M. J. R. [2] ; Ponge, D. [1] ; Gault, B. [1] ; Sandim, H. R. Z. [2] ; Raabe, D. [1]
Total Authors: 7
[1] MPIE, D-40237 Dusseldorf - Germany
[2] Univ Sao Paulo, Lorena Sch Engn, BR-12602810 Lorena, SP - Brazil
Total Affiliations: 2
Document type: Journal article
Source: ACTA MATERIALIA; v. 166, p. 178-191, MAR 2019.
Web of Science Citations: 1

Austenite (gamma) reversion in a cold-rolled 17.6 wt.% Mn steel was tracked by means of dilatometry and in situ magnetic measurements during slow continuous annealing. A splitting of the gamma-reversion into two stages was observed to be a result of strong elemental partitioning between gamma and alpha'-martensite during the low temperature stage between 390 and 575 degrees C. Atom probe tomography (APT) results enable the characterization of the Mn-enriched reversed-gamma and the Mn-depleted remaining alpha'-martensite. Because of its lower Mn content, the reversion of the remaining alpha'-martensite into austenite takes place at a higher temperature range between 600 and 685 degrees C. APT results agree with partitioning predictions made by thermo-kinetic simulations of the continuous annealing process. The critical composition for gamma-nucleation was predicted by thermodynamic calculations (Thermo-Calc) and a good agreement was found with the APT data. Additional thermo-kinetic simulations were conducted to evaluate partitioning-governed gamma-growth during isothermal annealing at 500 degrees C and 600 degrees C. Si partitioning to gamma was predicted by DICTRA and confirmed by APT. Si accumulates near the moving interface during gamma-growth and homogenizes over time. We used the chemical composition of the remaining alpha'-martensite from APT data to calculate its Curie temperature (T-Curie) and found good agreement with magnetic measurements. These results indicate that elemental partitioning strongly influences not only gamma-reversion but also the T-Curie of this steel. The results are important to better understand the thermodynamics and kinetics of austenite reversion for a wide range of Mn containing steels and its effect on magnetic properties. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. (AU)

FAPESP's process: 17/04444-1 - Study of microstructural stability and magnetic properties of Fe-Mn-C TRIP/TWIP steels
Grantee:Maria Jose Ramos Sandim
Support Opportunities: Regular Research Grants
FAPESP's process: 15/26409-8 - A comparative study of the microstructural stability and magnetic properties of two Fe-Mn-C (1,5%Mn and 17%Mn) steels
Grantee:Isnaldi Rodrigues de Souza Filho
Support Opportunities: Scholarships in Brazil - Doctorate
FAPESP's process: 17/17170-7 - Advanced microstructural characterization of two Fe-Mn-C steel grades (1.5 Mn wt-perc. and 17 Mn wt-perc.) in different metallurgical conditions
Grantee:Isnaldi Rodrigues de Souza Filho
Support Opportunities: Scholarships abroad - Research Internship - Doctorate