Control of nano-scale MX dispersion in grade 91 steel through thermo-mechanical treatment

Benjamin Shassere, Yukinori Yamamoto, Sudarsanam Suresh Babu

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

Detailed microstructure characterizations of Grade 91 (modified 9Cr-1Mo, ASTM A387) steel were performed after a thermo-mechanical treatment (TMT). This process includes rolling at temperatures above or below the ? and a+? phase field with 10% to 17% plastic strains, followed by an isothermal aging in the a+? phase field, which aims at enhancing very fine MX (M: Nb and V, X: C and N) dispersion within a martensitic matrix. Such pre-existing MX precipitates are expected to be stable during welding and improve the creep resistance of the fine grained heat affected zone in contrast to standard "normalization and tempering" heat-treatment. High number density of MX precipitates was dispersed readily after TMT, resulting in cross-weld creep properties with nearly 100% longer creep-life compared to the standard heat-treated samples at a test condition at 600°C and 100MPa. The competition between MX and M23C6 precipitation after TMT as well as their correlation to high-temperature strengthening mechanisms were discussed.

Original languageEnglish
Title of host publicationPTM 2015 - Proceedings of the International Conference on Solid-Solid Phase Transformations in Inorganic Materials 2015
EditorsLong-Qing Chen, Matthias Militzer, Gianluigi Botton, James Howe, Chadwick Sinclair, Hatem Zurob
PublisherInternational Conference on Solid-Solid Phase Transformations in Inorganic Materials 2015
Pages1161-1168
Number of pages8
ISBN (Electronic)9780692437360
StatePublished - 2015
EventInternational Conference on Solid-Solid Phase Transformations in Inorganic Materials 2015, PTM 2015 - Whistler, Canada
Duration: Jun 28 2015Jul 3 2015

Publication series

NamePTM 2015 - Proceedings of the International Conference on Solid-Solid Phase Transformations in Inorganic Materials 2015

Conference

ConferenceInternational Conference on Solid-Solid Phase Transformations in Inorganic Materials 2015, PTM 2015
Country/TerritoryCanada
CityWhistler
Period06/28/1507/3/15

Funding

The authors thank Dr. Xinghua Yu for his comments on this manuscript. Research sponsored by the Crosscutting Research Program, Office of Fossil Energy, U.S. Department of Energy. 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, worldwide 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-accessplan).

Keywords

  • Creep
  • Grade 91
  • Thermo-mechanical treatment
  • Weld

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