Crack tip opening angle (CTOA) has been recognized as a measure of the resistance of a material to fracture in cases where there is a large degree of stable-tearing crack extension during the fracture process. The current research has applied the CTOA concept in pipeline characterization. The fracture toughness behavior of X100 pipeline steel through a girth weld section was investigated by use of a modified double cantilever beam specimen. A test technique for direct measurement of the steady state CTOA was presented. Optical imaging was used to record the uniform deformation of a crack edge on a specimen surface. The CTOA was determined 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 valued as a very promising and convenient fracture criterion for the assessment of ductile fracture resistance in base metals and welds.
Fracture toughness through a welded pipeline section - Crack tip opening angle criterion -
Technical, Economic and Ecological Aspects, International Conference Welding and Materials, 2007 ; 225-234
Welding in the World ; 51 , Sh Tg
2007
10 Seiten, 9 Bilder, 2 Tabellen, 15 Quellen
Conference paper
English
Fracture toughness and safety assessment of X65 offshore pipeline welded joints
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