University of Oulu

Mohammadnezhad, Mahyar; Javaheri, Vahid; Shamanian, Morteza; Rizaneh, Shahram; Szpunar, Jerzy A. (2018) Insight to the microstructure characterization of a HP austenitic heat resistant steel after long-term service exposure. Acta Metallurgica Slovaca, Vol. 24, 2018, No. 4, p. 296-305. http://dx.doi.org/10.12776/ams.v24i4.1160

Insight to the microstructure characterization of a HP austenitic heat resistant steel after long-term service exposure

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Author: Mohammadnezhad, Mahyar1; Javaheri, Vahid2; Shamanian, Morteza1;
Organizations: 1Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran
2Department of Material Engineering and Production Technology, University of Oulu, Oulu 90570, Finland
3Department of Mechanical Engineering, University of Saskatchewan, Saskatoon, SK, S7N5A9, Canada
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.1 MB)
Persistent link: http://urn.fi/urn:nbn:fi-fe201901071465
Language: English
Published: Technical University in Kosice, 2018
Publish Date: 2019-01-07
Description:

Abstract

Heat-resistant steels of HP series (Fe-25Cr-35Ni) are used in high temperature structural applications. Their composition include Nb as strong carbide former. Electron Backscatter Diffraction (EBSD) investigations revealed that, in the as-cast condition, alloys exhibit austenitic matrix with intergranular primary carbides such as MC, M23C6 and/or M7C3. During exposure at a high temperature, phase transformations occurred: chromium carbides of M7C3 type transform into the more stable M23C6 type, intergranular M23C6 carbides precipitate, and Lave phase due to increase of Niobium activity with temperature increase, as thermodynamic simulation confirmed. Therefore, combination of EBSD-EDS technique with thermodynamic calculation is one of the novel and most accurate method to investigation of phase transformation, as the precipitations are identified on the basis of their crystal structure, chemical composition and their thermodynamic features.

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Series: Acta metallurgica Slovaca
ISSN: 1335-1532
ISSN-E: 1338-1156
ISSN-L: 1335-1532
Volume: 24
Issue: 4
Pages: 296 - 305
DOI: 10.12776/ams.v24i4.1160
OADOI: https://oadoi.org/10.12776/ams.v24i4.1160
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
Subjects:
Copyright information: © 2018 The Authors and Acta Metallurgica Slovaca.