Flaw Evaluations Using Master Curve Methodology

Abstract

The Master Curve (MC) reference temperature, T0, characterizes the fracture performance of pressure vessel steels in the ductile-brittle transition region. An MC-based flaw-evaluation analysis procedure that accounts for the variations of stress intensity factor, temperature, constraint, and material conditions is presented. The analysis procedure is applied to an example problem of pressure-temperature curve construction for a Section XI, Appendix G, internal, axial, semi-elliptical surface flaw subjected to a simple cool-down transient. The results show that the enhancement in the fracture toughness due to constraint loss in the ductile-brittle transition region as seen in data from test specimen geometries does not always translate to similar benefits in structural applications. Analyses such as those carried out in this work are necessary to quantify the potential benefit for each application.