Creep strength behavior of boron added P91 steel and its weld in the temperature range of 600-650 °C

J. Swaminathan, C. R. Das, Jayashree Baral, C. Phaniraj, R. N. Ghosh, S. K. Albert, A. K. Bhaduri

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review


One of the promising ways for mitigation of Type IV cracking - a failure by cracking at the intercritical/fine grained heat affected zone, a life limiting problem in advanced 9-12 Cr ferritic steel weld like that of P91 is through modification of alloy composition by addition of boron. Addition of boron was observed to improve the microstructure at the weld zone and hence the creep strength. In the present work, boron (100 ppm with controlled nitrogen) added P91 steel after normalizing at 1050°C and 1150°C and tempered at 760°C were studied for the creep behavior in the base metal and welded condition in the temperature range of 600-650°C. Creep strength was characterized in terms of stress and temperature dependence of creep rate and rupture time. Weld creep life was reduced compared to the base metal with rupture occurring at the ICHAZ (Type IV crack). However at longer time (at lower stress levels) exposure creep crack moves from weld metal to HAZ (Type II crack). Rupture life was found to superior for the base and weld in the boron containing steel when higher normalizing temperature is used. Estimation of 105 h was attempted based on short term rupture data available and weld strength factors were calculated. Observed values are better for P91BH condition than the values for P91BL condition as well as those available for P91 in open literature.
Original languageEnglish
Title of host publicationProceedings of the 2014 Energy Materials Conference
PublisherTMS, The Minerals, Metals and Materials Society
Publication date2014
ISBN (Print)978-1-119-02794-2
Publication statusPublished - 2014
Externally publishedYes
EventEnergy Materials 2014 - Xi'an, China
Duration: 4 Nov 20146 Nov 2014


ConferenceEnergy Materials 2014
SeriesEnergy Materials 2014, Conference Proceedings


  • Boron addition
  • Creep
  • P91 steel
  • Type IV cracking

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