Characterisation of the creep-fatigue behaviour of a 1CrMoV turbine steel

This paper concerns the creep-fatigue lifetime assessment of a 1CrMoV steel. A procedure based on the calculation of fatigue and creep damage fractions and their summation according to a non-linear interaction rule is applied for the endurance evaluation of isothermal fatigue and service-like thermomechanical fatigue tests performed with plain (uniaxial) and notched testpieces. In order to avoid the uncertainties associated with heat-to-heat variability, testpieces were manufactured from a single heat, for which the fatigue and creep deformation/endurance properties were specifically characterised. With the availability of a reliable constitutive model, finite element calculations could be used to determine the local stress-strain response at the position of crack initiation in each test. The predictive capabilities of the proposed approach for lifetime calculation as well as the suitability of uniaxial fatigue and creep data for the damage assessment of notched components are evaluated.