USE OF A BRITTLE NOTCH DWTT SPECIMEN TO PREDICT FRACTURE CHARACTERISTICS OF LINE PIPE STEELS.

The ductile fracture propagation of high toughness line pipe steels was evaluated by brittle notch Drop Weight Tear Test (DWTT), pressed notch DWTT, and Charpy V-notch specimens. A comparison of the upper plateau energies and examination of the fracture surfaces showed that there is extraneous initiation energy in the standard DWTT, Dynamic Tear Test, and Charpy specimens. To eliminate the extraneous initiation energy, the brittle notch DWTT specimen was used. A relationship was developed to convert the brittle notch DWTT energy to the equivalent resistance of a Charpy size specimen. The equivalent Charpy energy can be used with existing formulations to predict unstable ductile fracture behavior in pipelines.