Characterization of Crack Surface Morphology of Reheat and Hydrogen Assisted Cracks in Submerged Arc Weld Deposits of 2-1/4Cr-1Mo-V (22V) Steels
M. Trent, C. Lundin, M. Prager
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This research was undertaken in response to several incidents that have been reported with regard to submerged arc weld deposit cracking in 2-1/4Cr-1Mo-V (22V) pressure vessels. The study specifically involved the characterization and comparison of the crack surface morphology of reheat cracks (RHC) and hydrogen assisted cracks (HAC) by scanning electron microscopy (SEM) so that the cracking mode could be clearly differentiated. The study utilized the Notched C-Ring Reheat Cracking Test (NCRRCT) developed by the Materials Joining Group at the University of Tennessee as well as a Modified Hydrogen Sensitivity Cracking Method. The test results clearly showed distinct differences in crack surface morphologies for the two modes of cracking. The unique crack surface features permitted the unequivocal differentiation of the cracking mode. Thus, other investigators will be able use the crack surface images presented in this work as a basis of comparison for their own evaluations. The current research will enable investigators to positively classify weld deposit cracking in the 22V alloy system and thus eliminate time-consuming efforts to solve specific cracking incidents.