01/10/2017 Pressing & Sintering

Modelling the SN-curve for PM steels using a fracture mechanics approach

Whenever designing a component it is important to properly take fatigue related phenomena into account, both to ensure safe operation, but also to allow PM to be used in ever more demanding applications. In previous papers it was shown how the endurance limit of PM steels can be modelled using a fracture mechanics approach combined with an extreme value statistics treatment of the porosity. With this approach it was possible to include both the influence of density and stress concentrations in one comprehensive model. In this paper it is investigated how the model can be extended to include also the short life portion of the SN-curve. This is accomplished by also including fatigue crack propagation in the fracture mechanics model. The use of the model is demonstrated on a chromium based PM steel for sinter hardening applications.