This paper summarizes efforts on improving the methodology for arrest of unstable axial ductile crack propagation for the assessment of new and future gas pipeline projects. The past ductile fracture methodologies generally involve using the Charpy V-notch test, but that test has proven to be unreliable for high toughness materials and for materials that have rising-shelf energies, and is questionable for higher strength steels than X70 grade linepipe. The improved methodology utilizes the energy from a full-thickness impact specimen, of which the DWTT is the most frequently used. Various modified-notch specimens have been proposed in order to obtain the propagation energy component of the tests. On-going efforts involve developing a more fundamental relationship between technically defensible steady-state crack propagation fracture parameters and the DWTT energy. Recent experimental dynamic data and fracture analyses are presented in this paper.
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