Creep-fatigue crack growth in chromium-molybdenum-vanadium base material and weldments

An experimental study was performed to characterize the creep deformation and creep-fatigue crack growth (CFCG) behavior of an ex-service steam turbine casing 1Cr-1Mo-0.25V steel and its repair weldments at 565;Two levels of degraded base metal conditions (DI and DII) and their weldments were tested using trapezoidal loading waveforms with hold times of 0, 60 and 600 seconds. In-situ measurements of load-line deflection changes during the hold time were performed. The creep-fatigue crack growth rates, (da/dt);A new analytical scheme for calculating (C;Some anomalous trends in the initial portions of da/dN versus ;Microstructural observations are presented and the effect mismatch between base metal and weld metal properties on crack growth is discussed.