Fatigue behaviour of large forgings containing natural defects

In principle the presence of large steelmaking defects in components can jeopardise their operational integrity. This means that not only reliable non- destructive testing techniques, but also methods for the evaluation of the potential for crack initiation and propagation from these defects must be available. In order to test the assumptions involved in the analysis, several forgings with defects were investigated. Specimens containing the defects were subjected to fatigue loading. Through a comparison of the extent of crack initiation and propagation from the defects it could be seen quantitatively to what extent fracture mechanics can be applied.