Effectiveness Verification of Creep-Fatigue Assessment Procedures for Fast-Starting Steam Turbines

Abstract

The paper reviews the methodology adopted in a Swiss Research Collaboration to devise a component-feature representative testpiece geometry and the thermo-mechanical fatigue (TMF) cycle parameters necessary to closely simulate the most arduous conceivable operating duties in steam turbines exposed to cyclic operation. Implementation of these service-like experimental conditions provides a practical indication of the effectiveness of deformation and crack initiation endurance predictions, in particular during fast turbine start-up conditions. Comprehensive post test inspection also provides evidence to demonstrate the physical realism of the laboratory simulations in terms of the creep-fatigue damage generated during the benchmark tests. Mechanical response results and physical damage observations are presented and their practical implications evaluated.

Advanced constitutive modelling for creep-fatigue assessment of high temperature components

“…Several low cycle fatigue (LCF), cyclic/hold (C/H) and creep tests at different temperatures and for different heats of the alloy had been conducted to provide necessary information for employment of the introduced creep-fatigue assessment procedure for component/structure assessment (Hosseini et al, 2015a). One solution, in the absence of appropriate service experience, is to verify the effectiveness of new assessment procedures applied to components manufactured from new materials and operated in new ways using the results from component feature specimen service-cycle TMF benchmark tests (Holdsworth et al, 2012). This approach is being adopted in the following study.…”