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A nanoindentation study on grain-boundary contributions to strengthening and aging degradation mechanisms in advanced 12 Cr ferritic steel

Published online by Cambridge University Press:  03 March 2011

Jae-il Jang ,
Sanghoon Shim ,
Shin-ichi Komazaki  and
Tetsuya Honda
Jae-il Jang
Affiliation:
Division of Materials Science and Engineering, Hanyang University, Seoul 133-791, Korea
Sanghoon Shim
Affiliation:
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831; and Department of Materials Science and Engineering, The University of Tennessee, Knoxville, Tennessee 37996-2200
Shin-ichi Komazaki*
Affiliation:
Department of Materials Science and Engineering, Muroran Institute of Technology, Muroran 050-8585, Japan
Tetsuya Honda
Affiliation:
Department of Materials Science and Engineering, Muroran Institute of Technology, Muroran 050-8585, Japan
*
a) Address all correspondence to this author. e-mail: komazaki@mmm.muroran-it.ac.jp
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Abstract

Nanoindentation experiments and microstructural analysis were performed on advanced 12% Cr ferritic steel having extremely fine and complex martensitic microstructures, to answer unsolved questions on the contributions of grain boundaries to strengthening and aging degradation mechanisms in both as-tempered and thermally aged steels. Interesting features of the experimental results led us to suggest that among several high angle boundaries, block boundary is most effective in enhancing the macroscopic strength in as-tempered virgin sample, and that a decrease in matrix strength rather than reduction in grain-boundary strengthening effect is primarily responsible for the macroscopic softening behavior observed during thermal exposure.

Keywords

Grain boundariesHardnessStrength
Type
Articles
Information
Journal of Materials Research , Volume 22 , Issue 1 , January 2007 , pp. 175 - 185
Copyright
Copyright © Materials Research Society 2007

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