MATERIALS TRANSACTIONS
Online ISSN : 1347-5320
Print ISSN : 1345-9678
Effect of Nano-Size Oxide Particle Dispersion and δ-Ferrite Proportion on Creep Strength of 9Cr-ODS Steel
Satoshi OhtsukaTakeji KaitoSawoong KimMasaki InoueTai AsayamaMasato OhnumaJunichi Suzuki
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2009 Volume 50 Issue 7 Pages 1778-1784

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Abstract

The effects of chemical compositions on the microstructure and high-temperature creep strength of 9Cr-ODS steel was discussed in the light of quantitative data of δ-ferrite proportion and nano-size oxide particle dispersion, which were evaluated by dilatometric analysis and small angle neutron/X-ray scattering analysis, respectively. These quantitative data are well consistent with the conventional data obtained by transmission electron microscope. Both data indicate that the important microstructural feature for creep strength improvement of the 9Cr-ODS steel is the number density of nano-size oxide particles, and ferrite/martensite (F/M) duplex structure is favorable for high population nano-size oxide particle dispersion. Both optimization of excess oxygen concentration and control of the F/M duplex structure are promising technique for nano-structure control of 9Cr-ODS steel. Tungsten solid solution strengthening appears to be small compared with oxide dispersion strengthening enhanced by duplex microstructure formation.

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© 2009 The Japan Institute of Metals and Materials
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