Prediction model on cleavage fracture initiation in steels having ferrite-cementite microstructures - Part I: Model presentation

A prediction model on a cleavage fracture initiation in ferrite-cementite steels is presented. The model requires only information of microstructures without any adjustable parameters. The model is characterized in a multiscale framework based on the Monte Carlo method. A fracture process of three stages is assumed; (I) crack nucleation at cementite particle; (II) crack propagation into ferrite matrix; (III) crack propagation across grain boundary. An active zone is divided into volume elements where microstructures are assigned. Cleavage fracture is assumed to initiate at the time when all the fracture conditions are simultaneously satisfied in any one of the volume elements.