The fracture toughness of high strength steels is commonly determined by standard methods using Compact tension (CT) or Single edge notched bend (SENB) specimens. In the past the Circumferentially Notched Tension (CNT) geometry has been reported as a potential candidate for determining the fracture toughness of highly constrained cracks, theoretically approaching plane strain conditions, even for small specimen dimensions. The goal of this study is to develop a more fundamental understanding of the CNT methodology and apply it to high strength S690QT steel. An alternative prefatiguing method was developed and a straightforward relation was established between the Crack Mouth Opening Displacement (CMOD) and the Crack Tip Opening Displacement (CTOD). With the new experimental aspects, it proved feasible to determine upper-shelf CTOD values for S690QT steel, using small CNT specimens (D = 12 mm), tested at room temperature with a relative high loading rate. Furthermore, CNT low temperature values were found comparable to those of conventional SENB tests. Hence, the research demonstrates that CNT geometry allows for small scale high loading rate specimen testing, resulting in simple, rapid and cost effective fracture toughness determination.

Original languageEnglish
Title of host publicationTMS 2018 - 147th Annual Meeting and Exhibition
Subtitle of host publicationSupplemental Proceedings
Editors The Minerals, Metals & Materials Society Editor
Place of PublicationCham, Switzerland
ISBN (Print)9783319725253
Publication statusPublished - 2018
Event147th Annual Meeting and Exhibition of the Minerals, Metals and Materials Society, TMS 2018 - Phoenix, United States
Duration: 11 Mar 201815 Mar 2018

Publication series

NameMinerals, Metals and Materials Series
VolumePart F12
ISSN (Print)23671181
ISSN (Electronic)23671696


Conference147th Annual Meeting and Exhibition of the Minerals, Metals and Materials Society, TMS 2018
CountryUnited States

    Research areas

  • Circumferentially notched tensile test, Fracture toughness, High strength steel

ID: 42964537