Grain structural characterization of 9Cr–ODS steel aged at 973 K up to 10,000 h by electron backscatter diffraction

• Published in: Journal of nuclear materials 2014-12, Vol.455 (1-3), p.568-572
• Main Authors: Li, Yanfen, Abe, Hiroaki, Li, Feng, Satoh, Yuhki, Matsukawa, Yoshi, Matsunaga, Tetsuya, Muroga, Takeo
• Format: Article
• Language: English
• Subjects: Chromium steels; Density; Electron back scatter diffraction; Grain structure; Grains; Misorientation; Nuclear engineering; Structural steels
• ISSN: 0022-3115
• DOI: 10.1016/j.jnucmat.2014.08.047

In this work, thermal aging experiments on 9Cr-ODS steel were carried out at 973 K from 100 h up to 10,000 h, and grain structural evolution was investigated mainly focusing on analyses by electron backscatter diffraction (EBSD). The EBSD maps revealed no significant morphological changes in the matrix grain structure under the long-term aging. Grain size increased slightly with increasing periods of aging time from 100 h to 10,000 h. Distribution of misorientation angles was not affected by the thermal aging. The fraction of low misorientation angles comprised of subgrains was about 40% before aging, and decreased slightly by aging time up to 10,000 h. Total grain boundary length and density per unit area did not change significantly by aging up to 5000 h. They decreased slightly after aging for 10,000 h, which may be caused by slight recovery of microstructure. However, the effects of slight changes in the grain structure on mechanical properties are expected to be negligible.