Weldability Evaluation of High Chromium, Ni-Base Filler Metals Using the Cast Pin Tear Test

High chromium, nickel-base filler metals have been commonly used throughout the nuclear power industry for the weld overlay repair of dissimilar metal welds. These alloys provide optimum resistance to primary water stress corrosion cracking in nuclear power plant cooling systems. However some of these nickel alloys present weldability challenges including susceptibility to solidification cracking and ductility dip cracking. ERNiCrFe-7A (52M) and ERNiCrFe-13 (52MSS) filler metals, including two heats of 52M and one heat of both 52MSS and 690Nb, have been evaluated in this study. The susceptibility to solidification cracking was evaluated using the cast pin tear test (CPTT). The CPTT was also used to evaluate the effect of dilution between two heats of ERNiCr-3 (FM82) on the solidification cracking behavior. Metallurgical characterization using light optical microscopy, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) in the SEM has been performed in order to identify solidification cracking mechanisms, and to study the effect of liquid film formation and backfilling on cracking susceptibility.