X 9Cr-1Mo 㗰㒊㔞ホ

Translated title of the contribution: Quantitative evaluation of creep voids in Mod.9Cr-1Mo steel welded joints with X - Ray micro-tomography

Hideki Tsuruta, Hiroyuki Toda, Masataka Yatomi, Kimiaki Yoshida, Akihisa Takeuchi, Masayuki Uesugi, Masaaki Tabuchi, Hiromichi Hongou

Research output: Contribution to journalArticle


High-chromium ferritic resisting steels have been commonly used for high temperature components of USC boilers. However, it is well known that in the welded joints TYPE IV damage occurs in the fine-grained HAZ during long-term use under elevated temperature, due to the multiaxial stress at the fine-grained HAZ region. TYPE IV damage develops by the creep void nucleation at grain boundaries, following the void growth and coalescence. In order to measure the amount of creep damage, the distribution of voids on two-dimensional cross section is normally observed. However, the damage evaluation has a limitation from the point of accuracy because the void grows three-dimensionally. Recently, X-ray CT has been applied to observe damage distribution in three dimensions, and it is known that X-ray μ-CT in SPring-8, which is synchrotron radiation facility, can detect a void of about 1 μm diameter. In this paper, the TYPE IV damage is observed with X-ray μ-CT. The amount of void nucleation and the size of voids in the fine-grained HAZ region with time are quantitatively evaluated. Comparison between the creep damage evaluations based on two dimensional cross section (average diameter, area fraction and number density) and three dimensional void observations is conducted. It appears that the evaluation based on the area fraction on cross section is closest to that in three dimensions and therefore the most suitable evaluation.

Original languageJapanese
Pages (from-to)599-606
Number of pages8
JournalZairyo/Journal of the Society of Materials Science, Japan
Issue number8
Publication statusPublished - Jan 1 2019


All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

Cite this

Tsuruta, H., Toda, H., Yatomi, M., Yoshida, K., Takeuchi, A., Uesugi, M., ... Hongou, H. (2019). X 9Cr-1Mo 㗰㒊㔞ホ. Zairyo/Journal of the Society of Materials Science, Japan, 68(8), 599-606. https://doi.org/10.2472/jsms.68.599