Creep and damage investigation of improved 9%Cr steel welded joints

C. Schlacher, C. Sommitsch, P. Mayr, C. Gupta, Hiroyuki Toda, K. Usegi, Y. Suzuki

Research output: Chapter in Book/Report/Conference proceedingConference contribution

5 Citations (Scopus)

Abstract

Due to accelerated creep damage, martensitic 9%Cr welded joints fail prematurely in the fine-grained heat affected zone (FGHAZ). These failures in the FGHAZ are categorized as "Type IV cracking". In recent years, boron containing 9% Cr steels have been developed that suppress the FGHAZ formation in order to avoid Type IV cracking and that have increased crossweld creep strength. The advanced alloying concept is based on the balanced addition of boron and nitrogen. Creep tests of 9Cr3W3CoVNbBN steel crosswelds have been carried out up to 17000 hours at 650°C. The crossweld creep strength was analyzed and the damage evolution in crosswelds was investigated using synchrotron micro-tomography of creep exposed welded joints. Additionally, the microstructure of the crossweld specimens was investigated using optical and scanning electron microscopy and electron backscatter diffraction. Creep void formation along the original prior austenite grain boundaries, at a certain distance to the weld fusion line, in the heat affected zone was observed. Electron backscatter diffraction images revealed the incomplete suppression of grain refinement along the prior austenite grain boundaries. These newly formed small grains have been identified as the main reason for the increased creep void formation in this area.

Original languageEnglish
Title of host publicationTrends in Welding Research - Proceedings of the 9th International Conference
Pages376-381
Number of pages6
Publication statusPublished - Jul 31 2013
Externally publishedYes
Event9th International Conference on Trends in Welding Research - Chicago, IL, United States
Duration: Jun 4 2012Jun 8 2012

Publication series

NameASM Proceedings of the International Conference: Trends in Welding Research

Other

Other9th International Conference on Trends in Welding Research
CountryUnited States
CityChicago, IL
Period6/4/126/8/12

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Mechanical Engineering

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  • Cite this

    Schlacher, C., Sommitsch, C., Mayr, P., Gupta, C., Toda, H., Usegi, K., & Suzuki, Y. (2013). Creep and damage investigation of improved 9%Cr steel welded joints. In Trends in Welding Research - Proceedings of the 9th International Conference (pp. 376-381). (ASM Proceedings of the International Conference: Trends in Welding Research).