Irradiation hardening and ductility loss of Eurofer97 steel variants after neutron irradiation to ITER-TBM relevant conditions

Research output: Contribution to journalArticlepeer-review

Authors

  • Arunodaya Bhattacharya
  • Chen Xiang
  • Tim Graening
  • Josina W. Geringer
  • Jordan Reed
  • Luciano Pilloni
  • Dmitry Terentyev
  • Athina Puype
  • Thak Sang Byun
  • Yutai Katoh
  • Michael Rieth
  • Steve J. Zinkle

Institutes & Expert groups

  • ORNL - Oak Ridge National Laboratory
  • ENEA - Italian National Agency for New Technologies
  • OCAS - OnderzoeksCentrum voor de Aanwending van Staal - Belgium
  • IKET KIT INE - Karlsruhe Institute of : Institute for Nuclear Waste Disposal
  • University of Tennessee

Documents & links

Abstract

Ten Eurofer97 steel variants, produced by non-standard fabrication-processing routes and modified alloying chemistries, were studied by neutron irradiations in the high flux isotope reactor. The irradiations were performed to ITER-TBM relevant conditions of ~255–350 .C, 2.94–3.24 dpa. We quantified the irradiation-induced degradation of the steels using mechanical property tests. All the steels suffered from irradiation hardening, where a significant increase in Vickers microhardness and yield stress (sYS) occurred, accompanied with severe loss of tensile elongation. The extent of hardening was material dependent. For Tirr = 300±30 .C, most steels showed sYS increase in the range of ~30% to as high as ~66%, except for a low temperature tempered steel with sYS increase below 15%. Despite large losses in elongation, most failures were ductile. Significant post-necking ductility was retained with reduction in area (RA) between 65–75%, but <50% for low temperature tempered steels. The ultimate tensile stress to yield stress (sUTS/sYS) ratios decreased significantly after irradiation, highlighting irradiation-induced strain hardening capacity reduction. No major effect of irradiation on the plastic instability stress (sPIS) and true fracture stress of the steels was observed. By comparing the tensile stresses in true stress units and with literature, the results suggest that RAFM steel designing should target materials with a large separation between sPIS and sYS, to ensure the materials can maintain large work hardening and uniform deformation capability after irradiation. The tensile data of the steels additionally revealed a compelling evidence of an inverse trend between the change in RA and increase in sYS of the neutron irradiated Eurofer97 type steels.

Details

Original languageEnglish
Article number112935
Pages (from-to)1-22
Number of pages22
JournalFusion Engineering & Design
DOIs
Publication statusPublished - 12 Nov 2021

Keywords

  • Eurofer97 steel, Neutron irradiation, Tensile properties, Irradiation-hardening, Fracture, Reduction in area

ID: 7290486