Evaluation of impacts of stress triaxiality on plastic deformability of RAFM steel using various types of tensile specimen

Taichiro Kato, Mitsuru Ohata, Shuhei Nogami, Hiroyasu Tanigawa

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


A case study on a fusion blanket design such as DEMO indicated that there could be some sections with high stress triaxiality, a parameter to evaluate the magnitude of plastic constraint, in the case of plasma disruption or coolant loss accident. Therefore, it is necessary to accurately understand the ductility loss limit of structural material in order to conduct the structural design assessment of the irradiated and embrittled fusion reactor blanket. Tensile tests were conducted by using three kinds of tensile specimen shapes to investigate of the plastic deformability of F82H. From the results, the fracture ductility is lower as the stress triaxiality is higher. Voids of the interrupted RB1 specimen were observed along grain boundaries and expanded parallel to the tensile axis. That of interrupted R0.2 specimen was rounded shape compared with those of RB1. The fracture surface of RB1 and R0.2 specimens were observed the elongated dimples and the equiaxed dimples without so much elongation, respectively. It is considered that the decrease of plastic deformability for the notched specimen was caused by the process of voids formation and crack growth due to the effect of plastic constraint of the notch.

Original languageEnglish
Pages (from-to)1631-1636
Number of pages6
JournalFusion Engineering and Design
Publication statusPublished - 2016 Nov 1


  • Reduced activation ferritic/martensitic steel
  • Small specimen testing technique
  • Stress triaxiakity
  • Tensile property

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Nuclear Energy and Engineering
  • Materials Science(all)
  • Mechanical Engineering


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