Carbon concentration measurements by atom probe tomography in the ferritic phase of high-silicon steels [electronic resource].

Published:: Washington, D.C. : United States. Dept. of Energy. Office of Science, 2016.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
Physical Description:: pages 359-368 : digital, PDF file
Additional Creators:: Oak Ridge National Laboratory, United States. Department of Energy. Office of Science, and United States. Department of Energy. Office of Scientific and Technical Information

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Summary:

Current studies using atom probe tomography (APT) show that bainitic ferrite formed at low temperature contains more carbon than what is consistent with the paraequilibrium phase diagram. However, nanocrystalline bainitic ferrite exhibits a non-homogeneous distribution of carbon atoms in arrangements with specific compositions, i.e. Cottrell atmospheres, carbon clusters, and carbides, in most cases with a size of a few nanometers. The ferrite volume within a single platelet that is free of these carbon-enriched regions is extremely small. Proximity histograms can be compromised on the ferrite side, and a great deal of care should be taken to estimate the carbon content in regions of bainitic ferrite free from carbon agglomeration. For this purpose, APT measurements were first validated for the ferritic phase in a pearlitic sample and further performed for the bainitic ferrite matrix in high-silicon steels isothermally transformed between 200 °C and 350 °C. Additionally, results were compared with the carbon concentration values derived from X-ray diffraction (XRD) analyses considering a tetragonal lattice and previous APT studies. In conclusion, the present results reveal a strong disagreement between the carbon content values in the bainitic ferrite matrix as obtained by APT and those derived from XRD measurements. Those differences have been attributed to the development of carbon-clustered regions with an increased tetragonality in a carbon-depleted matrix.

Report Numbers:

E 1.99:1337485

Subject(s):

Materials Science

Other Subject(s):

Note:

Published through SciTech Connect.
12/19/2016.
"KC0403040"
"ERKCZ01"
Acta Materialia 125 C ISSN 1359-6454 AM
Rementeria, Rosalia [Spanish National Research Council (CSIC), Madrid (Spain). Center for Metallurgical Research (CENIM), Dept. of Physical Metallurgy]; Poplawsky, Jonathan D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS)]; Aranda, Maria M. [Spanish National Research Council (CSIC), Madrid (Spain). Center for Metallurgical Research (CENIM), Dept. of Physical Metallurgy]; Guo, Wei [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS)]; Jimenez, Jose A. [Spanish National Research Council (CSIC), Madrid (Spain). Center for Metallurgical Research (CENIM), Dept. of Physical Metallurgy]; Garcia-Mateo, Carlos [Spanish National Research Council (CSIC), Madrid (Spain). Center for Metallurgical Research (CENIM), Dept. of Physical Metallurgy]; Caballero, Francisca G. [Spanish National Research Council (CSIC), Madrid (Spain). Center for Metallurgical Research (CENIM), Dept. of Physical Metallurgy].

Funding Information:

AC05-00OR22725
RFSR-CT- 2014-00019

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