Microstructure-informed statistical modelling of cleavage fracture in high strength steels considering through-thickness inhomogeneities

• Published in: Engineering fracture mechanics 2022-05, Vol.267, p.108432, Article 108432
• Main Authors: Jiang, Quanxin, Bertolo, V.M., Popovich, V.A., Sietsma, J., Walters, Carey L.
• Format: Article
• Language: English
• Subjects: Cleavage; Fracture toughness; Grain size; High strength steels; Inhomogeneity; Microstructural inhomogeneity; Microstructure; Parameters; Statistical modelling; Statistical models
• ISSN: 0013-7944; 1873-7315
• DOI: 10.1016/j.engfracmech.2022.108432

•A multi-barrier model for cleavage is modified to include the effect of plastic strain and deactivation of hard inclusions.•Grain boundaries rather than particle/matrix interfaces are identified as the barrier to microcrack propagation for the sample steel.•The effects of higher yield stress and finer grain size inside the segregation bands approximately cancel.•Niobium carbide inclusions that have lower fracture strength characterize the detrimental effect of segregation bands. Thick section S690 QT steel is modelled with a modified multibarrier model that is based on the weakest-link mechanism. Segregation bands are modelled as discrete layers which have different grain size, yield properties, and local fracture parameters from outside of the bands. The results show that embrittlement from segregation bands can only be adequately reflected if the inhomogeneities of the fracture parameters are accounted for. The present methodology quantitively captures the cooperation of complex microstructural features in cleavage and can facilitate the trade-off between the effects of various microstructural parameters in toughness control.