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  • Fracture toughness predictions for modern low carbon higher strength steels based on microstructural and micromechanistic approaches. Final report


Final report of Contract No. 7210-KA/327, 825, 126, 127, 826; 1 July 1996 to 1 July 1999

New or improved fracture criteria can be combined with numerical simulation methods (local approach to fracture) to predict fracture toughness of steels and failure behaviour of steel structures. Such models combine two important aspects: the understanding of the fracture behaviour on a microscale (essential for the development of steels with improved fracture resistance)) and the use of finite element methods.

Within this framework, the aims of this project are to contribute to a better understanding of the fracture mechanisms of low-carbon, high-strength steels (cleavage fracture, transition regime, ductile), to evaluate the relevance of existing criteria to describe these fracture mechanisms and, finally, to assess the ability of the local approach methodology to predict size, constraint and strain rate effects.

The main results of the project with respect to cleavage fracture fall into three main areas: proposed modification to the Beremin model in order to describe a statistical competition between several potential mechanisms, issues regarding transferability of Weibull parameters, and link between toughness and microstructure by identifying the initiation sites of fracture. Dealing with the transition regime (ductile tearing followed by cleavage fracture), a Gurson model (ductile fracture) is combined with the Beremin model. It is shown that that it can produce satisfactory predictions. For the ductile fracture, the Stroppe relation, which is a microstructural parameter-based model, is investigated. The predicted J integrals at physical crack initiation are consistent with the experimental ones. ones.

Additional information

Authors: STUREL T, IRSID, Maizièrez-les-Metz (FR);CARDINAL N, British Steel plc, Rotherham (GB);HORN A J, British Steel plc, Rotherham (GB);KARSTENSEN A D, The Welding Institute, Rotherham (GB);GOLDTHORPE M R, The Welding Institute, Rotherham (GB);SATTLER E, MPA Stuttgart (DE);POHL H, MPI, Düsseldorf (DE);KASPAR R, MPI, Düsseldorf (DE);HAGEDORN K E, MPI, Düsseldorf (DE)
Bibliographic Reference: EUR 20093 EN (2002), pp.207. Euro: 31:00
Availability: EUR-OP reference: KI-NA-20093-EN-S. Available from EUR-OP sales agents. URL:
ISBN: ISBN: 92-894-3151-2
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