Evaluation and Comparison of Double Clip Gauge Method and Delta 5 Method for CTOD Measurement in SE(T) Specimens

摘要

The experimental evaluation of the fracture toughness of line pipe steels and girth welds is increasingly performed through single edge notched tensile-SE(T)-testing. The notch constraint in these specimens closely matches that in pipes. This paper focused on the measurement of the crack tip opening displacement (CTOD). The double clip gauge method and the GKSS δ_5 method were compared based on experimental tests on both welded and nonwelded specimens. A good correspondence between both techniques was observed. The δ_5 method tended to result in a slightly lower estimation of crack driving force, which was explained by the difference between both CTOD definitions. Both techniques were concluded to be equivalent for the evaluation of CTOD in SE(T) specimens.