No abstract

No abstract

Based on a failure analysis of cut-off valves, this study investigated the selective corrosion behavior of cast nickel-aluminum bronze (NAB) by an immersion corrosion test and explained it with energy dispersive spectroscopy and microanalysis. Fracture analysis and finite element numerical simulation results showed that the joints of valve discs and seal rings were corroded first. Cast NAB contains α, β, and κ phases with different chemical compositions. Chemical component segregation is the fundamental reason for the difference in corrosion potential in seawater. After the ferric chloride immersion corrosion test, the corrosion cracks appeared at the grain boundary between the α phase and κ phase. Galvanic corrosion cells are formed at the phase boundary, and cracks and corrosion occur preferentially at the grain boundary.