Elizabeth S. Drexler, Yong-Yi Wang, Jeffrey W. Sowards, Marc Dvorak
Single edge-notch tension (referred to as SE(T) or SENT) tests are increasingly being used in the pipeline community, as they are a laboratory-scale fracture toughness test, capable of being performed on linepipe steels and welds. The constraint and loading conditions of the SENT specimens more closely correspond with actual field flaws than those of the conventional three-point-bend CTOD specimens. Our test matrix included two different, nominally X65 and one X80 base materials, and their girth welds and associated heat-affected zones (HAZ), with cracks initiating from the outer diameter of the pipe. Every effort was made to preserve as much of the through-thickness of the pipe material as possible. Tests on the weld and HAZ materials were conducted at room temperature and 3 to 4 low temperatures, as required to ascertain when the material was transitioning from ductile to brittle failure. One base material was welded with two different filler materials, one over-matched to the base material and the other under-matched. Results included: In general, at a given temperature, cracks propagated at lower energies in the weld material than in the HAZ or base material. Comparison of the J-integral curves for the under-matched and over-matched welds showed: o only minor differences at room temperature o greater toughness in the over-matched weld at lower temperatures (but still on the upper-shelf of the curves of the ductile-to-brittle transition temperature (DBTT)). Testing at low temperatures, but still on the upper shelf of the DBTT, appears to affect the weld material to a lesser degree than the HAZ, where significant increases in toughness were observed between room temperature and 80˚C.
Proceedings of the 8th International Pipeline Conference
, Wang, Y.
, Sowards, J.
and Dvorak, M.
SE(T) Testing of Pipeline Welds, Proceedings of the 8th International Pipeline Conference, Calgary, -1, [online], https://doi.org/10.1115/IPC2010-31325
(Accessed December 11, 2023)