High Temperature Crack Initiation and Defect Assessment of P22 Steel Weldments using Time Dependent Failure Assessment Method

Abstract

High temperature deformation and crack resistance of low alloy ferritic grade P22 steel weldments applied in power plants are reported. The creep crack initiation (CCI) and creep crack growth (CCG) data were determined using compact type (C(T)) and C-Shape (CS(T)) fracture mechanics specimens at 550 °C. The deformation and crack growth behaviour of similar weldment zones and significance of CCI and CCG in defect assessment of components were addressed. The weldments with industrially relevant properties were produced in butt welded pipe joint from which test specimens are sampled. The studied material covers a spectrum of microstructures and ductility over the weldment zones to give representative for a welded component. The emphasis is placed on the measurement and particularly analysis of crack initiation for failure assessment in P22 steel weldments. The particular importance of construction of isochronous curves for time dependent failure assessment diagram (TDFAD) method is reported. It is aimed to contribute to establishing guidelines for acceptable methodologies for testing, analysis and assessment of welded components using TDFAD for high temperature service.