Fracture behaviour of circumferential through wall cracked welded pipes in four point bending

The fracture behaviour of a structure with a crack in the middle of a weld is influenced by the mechanical properties of the neighbouring zones (base metal, weld metal and heat affected zone), the loading conditions and the pipe and weld geometry. Therefore, defect assessment procedures have been developed or modified in order to take into account all those parameters. Most of the applications of those new defect assessment procedures are concerned with fracture mechanics specimens. This paper deals with the case of circumferential through wall cracked welded pipe in bending. A limit moment expression for such overmatched configurations is proposed and used with the ARAMIS method and the new "equivalent material" method. The results of those two defect assessment procedures are compared with 3D finite element analyses. The new "equivalent material" method gives better results since, in contrast with the ARAMIS method, it includes strain hardening exponent of both weld and base metal. (C) 1999 Elsevier Science Ltd. All rights reserved.