Typical local compression effect on crack front straightness and fracture toughness

• Published in: Welding in the world Vol. 65; no. 9; pp. 1777 - 1790
• Main Authors: Ozawa, A. Takumi, Kosuge, B. Hiroaki, Mikami, C. Yoshiki, Kawabata, D. Tomoya
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.09.2021; Springer Nature B.V
• Subjects: Chemistry and Materials Science; Fracture toughness; Heat treating; Materials Science; Metallic Materials; Numerical analysis; Research Paper; Solid Mechanics; Straightness; Test procedures; Theoretical and Applied Mechanics; Sacrificial test; Numerical analysis; Critical CTOD; Fracture toughness test; Local compression
• ISSN: 0043-2288; 1878-6669
• DOI: 10.1007/s40194-021-01119-x

ISO 12135, which provides a fracture toughness test procedure, requires crack front straightness. In order to meet this requirement in weld specimens, Annex C to ISO 15653 provides a local compression (LC) technique. Although this technique has been used widely, some interested parties have reported that it often results in excessive underestimation of the critical CTOD. Following these previous studies, the authors reviewed the appropriate LC conditions and presented the typical effects of LC on fracture toughness and crack front straightness in this paper. In this regard, we conducted numerical analysis, sacrificial test, and fracture toughness test and investigated the LC effect on the crack front straightness and fracture toughness. In conclusion, a typical LC with an appropriate platen results in a straight crack front, but also has a large influence on fracture toughness, and it is difficult to solve this problem only by adjusting the amount of LC strain.