Numerical modelling of cleavage in high strength steels with parametric study on microstructures

One of the challenges in cleavage modelling is the strong sensitivity to material characteristics at the micro level. In this research, a microstructure-based method that is coupled with Finite Element Analysis is used to model the cleavage behavior of a S690 QT steel at -130°C. The method is a multi-barrier model which accounts for microcrack nucleation by hard inclusions and microcrack propagation based on the weakest link mechanism. In this article, parametric variations of grain size, second particle size, and second particle density are performed. This study can help inform the trade-off between microstructural parameters, and help a designer choose a process for controlling toughness. By comparing the simulations, it is found that the reduction of grain size is more effective than the reduction of brittle particle size and distribution on toughness improvement for the studied material.