Adapting a multi-component model to cyclic stress–strain behaviour under thermomechanical fatigue conditions

The cyclic stress–strain behaviour of metals and alloys in cyclic saturation can reasonably be described by means of simple multi-component models. In this study, this model concept was applied to thermomechanical fatigue loading. Two metallic engineering materials, which were found to be oppositional with respect to cyclic plastic deformation, were dealt with. One material is an austenitic stainless steel of type AISI304L which can be considered as an example for a rather ductile alloy. The second alloy is a third-generation near-gamma TiAl alloy which is characterized by a very pronounced ductile-to-brittle transition (DBT) within the temperature range of TMF cycling. The experimental observations regarding isothermal and non-isothermal stress–strain behaviour and the correlation to the underlying microstructural processes were used to further develop the TMF multi-composite model in order to accurately predict the TMF stress–strain response by taking the alloy-specific features into account.