Micromechanical-Based Models for Describing Damage of Ferritic Steels

Usually the safety margin against failure for precracked components is calculated with fracture mechanics approaches. Due to several severe limitations of these approaches, it was searched for alternative calculation models. Starting with McClintock and Berg in the sixties, so-called damage models have been developed for describing ductile fracture on the basis of micromechanical processes. The development of such kind of models is in progress now for nearly 50 years, but until today no model is generally accepted and incorporated into the international standards. In an extended introduction, the micromechanical phases of ductile rupture of metal and alloys are presented. Against this background, a summary of the evolution and the different kinds of micromechanical-based model approaches is given. The theoretical background, the advantages/ disadvantages and the limitations of the models are discussed critically. Finally non-local formulations of damage models are presented. Combinations of ductile damage models and models for cleavage to describe fracture in the brittle-ductile transition region are discussed.