Lu Cui

Validation of a Phenomenological Lifetime Estimation Method with Biaxial Experiments at High Temperature

Modern 9-12%Cr steels are widely used for steam turbine components. For the design optimization and lifetime estimation of steam turbines, it is very important to investigate and describe the deformation as well as crack initiation behavior at critical location of steam turbine components under multiaxial service-type loading conditions. In this paper a phenomenological lifetime estimation method was validated by multiaxial loading. The applicability and reliability of this lifetime estimation model was confirmed by a recalculation of biaxial creep fatigue tests performed on cruciform specimens of rotor steel X12CrMoWVNbN10-1-1 successfully.

Development of a phenomenological method for description of crack initiation behavior under thermo-mechanical fatigue loading

Description of crack initiation behavior under thermo-mechanical fatigue (TMF) of modern high chromium steel is prerequisite for design optimization of steam turbine components. In this paper a phenomenological method which envelopes the synthesis of stress-strain hysteresis loops according to cycle counting methods and the individual assessment of creep fatigue damage is extended to TMF with superimposed creep. Recalculation of such service-type experiments on specimen of rotor steel 10CrMoWVNbN shows acceptable results for deformation description and lifetime estimation.