Temperature and stress dependence of creep life of welded joints in strength enhanced high cr ferritic steels

K. Maruyama, K. Yoshimi, Y. Hasegawa, H. Morimoto, F. Masuyama

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1 Citation (Scopus)


Overestimation of creep life is a serious problem that happens in long term creep of welded joints made of 9-12%Cr ferritic steels. Creep rupture data of welded joints made of grades 91, 92 and 122 steels were subjected to multiregion analyses paying attention to change in activation energy Q for creep rupture life. A region with a low Q value was found in long term creep of the welded joints. Therefore, long term creep rupture life of the welded joints can be overestimated when it is evaluated by temperature acceleration tests based on a high Q value of short term data. The decrease in activation energy was closely related to the change in fracture location from base metal to heat affected zone. Activation energy and stress exponent for creep rupture life take similar values both in base metal and in the welded joint, though the transition to the low Q region starts at shorter time in cross-welded joints. This fact suggests that creep rupture life can be formulated in a unified manner irrespective of base metal or welded joint. Weld strength factor of high Cr ferritic steels should have a lower limit insensitive to service temperature.

Original languageEnglish
Pages (from-to)70-75
Number of pages6
JournalEnergy Materials: Materials Science and Engineering for Energy Systems
Issue number2
Publication statusPublished - 2009 Jun


  • Activation energy for creep life
  • Creep rupture life
  • High cr ferritic steel
  • Weld strength factor
  • Welded joint


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