Toughness of EW Pipe Seam Welds of Contemporary Steels

An extensive experimental program to characterize the Charpy-V-notch (CVN) impact toughness of ten contemporary Electric Welded (EW) pipes was recently completed to establish a database to support the revision of the EW seam weld Charpy toughness testing requirements in Canadian Standards Association (CSA) Z245.1-14. The toughness in these welds is lowest at or near the weld bond line (BL) within a narrow zone ±≈0.5 mm wide. It is feasible and desirable to position the BL notch to a precision to match this width, i.e. ±0.5 mm from the BL. In this paper, typical results of microstructure, micro-hardness, CVN toughness (i.e. absorbed energy) as a function of temperature and notch location, and fractography will be presented. CVN absorbed energy requirements for EW welds in CSA Z245.1 have been determined using a failure assessment diagram (FAD) procedure. The values of required CVN estimated from the FAD are close to those specified in CSA Z245.1-14 but are higher than the specification in CSA Z245.1-18.