Low constraint fracture toughness testing using SE(T) and SE(B) specimens

This work presents a brief review of current progress in fracture resistance test procedures to measure crack growth properties of pipeline steels using clamped SE(T) and shallow-crack SE(B) specimens. A central objective is to assess recently developed practices for J and CTOD resistance curve test methods with particular emphasis on the estimation procedures for J and CTOD as well as the experimental evaluation of stable crack growth. An overview of the fracture resistance test methodology based on the unloading compliance (UC) procedure is introduced to provide the requisite background to determine fracture resistance data for these fracture specimens. A rather comprehensive presentation of the estimation formulas to evaluate J (and, equivalently, CTOD) and crack length from load-displacement (CMOD) records is also given. Constraint effects in SE(B) and clamped SE(T) specimens in terms of the J−Q methodology are then described, followed by the presentation of key results for crack growth resistance testing conducted on low constraint fracture specimens extracted from typical pipe girth welds.