Corrosion resistance of nickel (Ni) -base alloy weld materials with about 30 wt.% and higher chromium (Cr) content was examined for application in a boiling water reactor (BWR) environment. The materials studied include alloy 82 weld materials modified with enhanced Cr content ranging from 30 to 36 wt.%, which had been specially developed in this study and alloy 52M. To evaluate stress corrosion cracking (SCC) resistance of highly corrosion-resistant materials, intergranular corrosion tests in boiling nitric-hydrofluoric acid as well as creviced bent beam (CBB) tests with cold worked materials were conducted.
All the weld materials with high Cr content showed significantly superior corrosion resistance to conventional alloy 82. Microstructural analyses showed oxide film morphology and grain boundary characteristics that provided mechanistic understanding of corrosion behaviors and resistance of the materials. During welding, all test materials with high Cr content showed good weldability comparable to conventional alloy 82, without noticeable weld defects in not-destructive examinations and bending tests and without significant oxide scales on weld bead surface, indicating no significant concern in their welding applications. All tests indicated excellent SCC resistance and applicability of the high Cr Ni-base alloy weld materials in BWR environments.