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Measurement of Weld Toughness - Crack Tip Opening Angle Criterion



Philippe P. Darcis, Joseph D. McColskey, Christopher N. McCowan, Thomas A. Siewert


The stable tearing behavior of X100 pipeline steel through a girth weld section was investigated using a modified double cantilever beam specimens. A test technique for direct measurement of the steady state crack tip opening angle (CTOA) criterion was presented. Optical imaging was used to record the uniform deformation of a crack edge on a specimen surface. The CTOA was measured during steady state crack growth by a direct measurement method using software developed for this study. The results demonstrate a slight improvement of the fracture resistance in the HAZ and a slight decrease in the weld metal. CTOA is a very promising and convenient fracture criterion for the measure of ductile fracture resistance in base metals and welds. Further study is warranted on the variety of matching and mismatching welds and base metals.
Welding Journal


crack tip opening angle, high strength pipeline steel, girth weld


Darcis, P. , McColskey, J. , McCowan, C. and Siewert, T. (2007), Measurement of Weld Toughness - Crack Tip Opening Angle Criterion, Welding Journal, [online], (Accessed April 13, 2024)
Created May 31, 2007, Updated October 12, 2021