Multiaxial fatigue behavior of EUROFER 97

Proportional and non-proportional multiaxial fatigue testing of tubular specimens have been performed under purely alternating strain-controlled loading in order to assess the lifetime behavior of the ferritic martensitic steel EUROFER 97 under multiaxial fatigue conditions. Both load paths and the phase shifts were varied. The first test series at room temperature was performed with fixed directions of the principal stresses and strains. A second test series was conducted under alternating tension–torsion loading. In this case no fixed principal axis system is obtained. In fact, rotating principal stresses and strains are included. In a further step, tests were performed at elevated temperatures (500 °C). The results obtained reveal the influence of the phase shift for different temperatures as well as the influence of test execution method (fixed or rotating principal stress system) for the same material.