Compositional analysis on the reverted austenite and tempered martensite in a Ti-stabilized supermartensitic stainless steel: Segregation, partitioning and carbide precipitation

J. D. Escobar; J. D. Poplawsky; G. A. Faria; J. Rodriguez; J. P. Oliveira; C. A.F. Salvador; P. R. Mei; S. S. Babu; A. J. Ramirez

doi:10.1016/j.matdes.2017.11.055

Compositional analysis on the reverted austenite and tempered martensite in a Ti-stabilized supermartensitic stainless steel: Segregation, partitioning and carbide precipitation

J. D. Escobar
, J. D. Poplawsky
, G. A. Faria
, J. Rodriguez
, J. P. Oliveira
, C. A.F. Salvador
, P. R. Mei
, S. S. Babu
, A. J. Ramirez

Materials MicroAnalysis

Research output: Contribution to journal › Article › peer-review

73 Scopus citations

Abstract

Controlling the amount of reverted austenite at room temperature allows for tailoring of mechanical properties in supermartensitic stainless steels. The austenite reversion and stabilization occurs during inter-critical tempering through partitioning of austenite-stabilizing elements. The degree of partitioning greatly depends on the reversion temperature, which dictates the local equilibrium conditions. Atom probe tomography and energy dispersive spectroscopy in transmission electron microscopy were used to study the austenite reversion mechanism in terms of the elemental distribution of austenite-stabilizing, ferrite-stabilizing and carbide forming elements. Synchrotron X-ray diffraction confirmed that the austenite equilibrium phase fraction was reached after 2.5 h of isothermal reversion at 625 °C, allowing for direct comparison with thermodynamic and kinetic calculations. However, such soaking time was not enough to produce compositional homogenization in the reverted austenite. The austenite reversion and stabilization mechanism was related mainly to strong partitioning of Ni. Negligible partitioning of Cr, Mo, Si and Ti were observed. Instead, these elements were strongly segregated at the reverted austenite/martensite interfaces. Carbon and Ti played a secondary role in the austenite stabilization through the precipitation of nano-sized Ti (C,N) with partial substitution of Ti by Mo. Virtually carbon-free austenite and martensite were observed away from the interfaces and precipitates.

Original language	English
Pages (from-to)	95-105
Number of pages	11
Journal	Materials and Design
Volume	140
DOIs	https://doi.org/10.1016/j.matdes.2017.11.055
State	Published - Feb 15 2018

Funding

This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ). The authors acknowledge the XTMS beamline members, the Brazilian Synchrotron Light Source (LNLS) and the Brazilian Nanotechnology National Laboratory (LNNano) for the support with the diffraction experiments; Villares Metals S.A. for the donation of the materials; and CNPq-SWE 02766/2014-4, FAPESP (2014/20844-1), FAPESP (2016/13466-6) for the PhD funding. APT was conducted at ORNL's Center for Nanophase Materials Sciences (CNMS), which is a U.S. DOE Office of Science User Facility. FIB and TEM measurements were performed at the Center for Electron Microscopy and Analysis (CEMAS), at The Ohio State University.

Keywords

Atom probe tomography
Austenite reversion
Isothermal tempering treatments
Synchrotron diffraction

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10.1016/j.matdes.2017.11.055

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Escobar, J. D., Poplawsky, J. D., Faria, G. A., Rodriguez, J., Oliveira, J. P., Salvador, C. A. F., Mei, P. R., Babu, S. S., & Ramirez, A. J. (2018). Compositional analysis on the reverted austenite and tempered martensite in a Ti-stabilized supermartensitic stainless steel: Segregation, partitioning and carbide precipitation. Materials and Design, 140, 95-105. https://doi.org/10.1016/j.matdes.2017.11.055

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title = "Compositional analysis on the reverted austenite and tempered martensite in a Ti-stabilized supermartensitic stainless steel: Segregation, partitioning and carbide precipitation",

abstract = "Controlling the amount of reverted austenite at room temperature allows for tailoring of mechanical properties in supermartensitic stainless steels. The austenite reversion and stabilization occurs during inter-critical tempering through partitioning of austenite-stabilizing elements. The degree of partitioning greatly depends on the reversion temperature, which dictates the local equilibrium conditions. Atom probe tomography and energy dispersive spectroscopy in transmission electron microscopy were used to study the austenite reversion mechanism in terms of the elemental distribution of austenite-stabilizing, ferrite-stabilizing and carbide forming elements. Synchrotron X-ray diffraction confirmed that the austenite equilibrium phase fraction was reached after 2.5 h of isothermal reversion at 625 °C, allowing for direct comparison with thermodynamic and kinetic calculations. However, such soaking time was not enough to produce compositional homogenization in the reverted austenite. The austenite reversion and stabilization mechanism was related mainly to strong partitioning of Ni. Negligible partitioning of Cr, Mo, Si and Ti were observed. Instead, these elements were strongly segregated at the reverted austenite/martensite interfaces. Carbon and Ti played a secondary role in the austenite stabilization through the precipitation of nano-sized Ti (C,N) with partial substitution of Ti by Mo. Virtually carbon-free austenite and martensite were observed away from the interfaces and precipitates.",

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doi = "10.1016/j.matdes.2017.11.055",

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Escobar, JD, Poplawsky, JD, Faria, GA, Rodriguez, J, Oliveira, JP, Salvador, CAF, Mei, PR, Babu, SS & Ramirez, AJ 2018, 'Compositional analysis on the reverted austenite and tempered martensite in a Ti-stabilized supermartensitic stainless steel: Segregation, partitioning and carbide precipitation', Materials and Design, vol. 140, pp. 95-105. https://doi.org/10.1016/j.matdes.2017.11.055

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T1 - Compositional analysis on the reverted austenite and tempered martensite in a Ti-stabilized supermartensitic stainless steel

T2 - Segregation, partitioning and carbide precipitation

AU - Escobar, J. D.

AU - Poplawsky, J. D.

AU - Faria, G. A.

AU - Rodriguez, J.

AU - Oliveira, J. P.

AU - Salvador, C. A.F.

AU - Mei, P. R.

AU - Babu, S. S.

AU - Ramirez, A. J.

PY - 2018/2/15

Y1 - 2018/2/15

N2 - Controlling the amount of reverted austenite at room temperature allows for tailoring of mechanical properties in supermartensitic stainless steels. The austenite reversion and stabilization occurs during inter-critical tempering through partitioning of austenite-stabilizing elements. The degree of partitioning greatly depends on the reversion temperature, which dictates the local equilibrium conditions. Atom probe tomography and energy dispersive spectroscopy in transmission electron microscopy were used to study the austenite reversion mechanism in terms of the elemental distribution of austenite-stabilizing, ferrite-stabilizing and carbide forming elements. Synchrotron X-ray diffraction confirmed that the austenite equilibrium phase fraction was reached after 2.5 h of isothermal reversion at 625 °C, allowing for direct comparison with thermodynamic and kinetic calculations. However, such soaking time was not enough to produce compositional homogenization in the reverted austenite. The austenite reversion and stabilization mechanism was related mainly to strong partitioning of Ni. Negligible partitioning of Cr, Mo, Si and Ti were observed. Instead, these elements were strongly segregated at the reverted austenite/martensite interfaces. Carbon and Ti played a secondary role in the austenite stabilization through the precipitation of nano-sized Ti (C,N) with partial substitution of Ti by Mo. Virtually carbon-free austenite and martensite were observed away from the interfaces and precipitates.

AB - Controlling the amount of reverted austenite at room temperature allows for tailoring of mechanical properties in supermartensitic stainless steels. The austenite reversion and stabilization occurs during inter-critical tempering through partitioning of austenite-stabilizing elements. The degree of partitioning greatly depends on the reversion temperature, which dictates the local equilibrium conditions. Atom probe tomography and energy dispersive spectroscopy in transmission electron microscopy were used to study the austenite reversion mechanism in terms of the elemental distribution of austenite-stabilizing, ferrite-stabilizing and carbide forming elements. Synchrotron X-ray diffraction confirmed that the austenite equilibrium phase fraction was reached after 2.5 h of isothermal reversion at 625 °C, allowing for direct comparison with thermodynamic and kinetic calculations. However, such soaking time was not enough to produce compositional homogenization in the reverted austenite. The austenite reversion and stabilization mechanism was related mainly to strong partitioning of Ni. Negligible partitioning of Cr, Mo, Si and Ti were observed. Instead, these elements were strongly segregated at the reverted austenite/martensite interfaces. Carbon and Ti played a secondary role in the austenite stabilization through the precipitation of nano-sized Ti (C,N) with partial substitution of Ti by Mo. Virtually carbon-free austenite and martensite were observed away from the interfaces and precipitates.

KW - Atom probe tomography

KW - Austenite reversion

KW - Isothermal tempering treatments

KW - Synchrotron diffraction

UR - https://www.scopus.com/pages/publications/85035804707

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DO - 10.1016/j.matdes.2017.11.055

M3 - Article

AN - SCOPUS:85035804707

SN - 0264-1275

VL - 140

SP - 95

EP - 105

JO - Materials and Design

JF - Materials and Design

ER -

Compositional analysis on the reverted austenite and tempered martensite in a Ti-stabilized supermartensitic stainless steel: Segregation, partitioning and carbide precipitation

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Keywords

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