The effect of duplex stainless steel microstructure on its cavitation morphology in seawater

An ultrasonically induced cavitation facility was used to study the effect of a cast duplex stainless steel (DSS) microstructure on its corrosion behavior in seawater. Under cavitation conditions, small cavities initiated in the ferritic matrix and at the ferrite–austenite boundaries. With the progress of cavitation, the attack concentrated in the austenitic phase and then spread to the ferritic phase and was associated with cleavage-like facets, ductile tearing, river patterns and crystallographic steps at later stages. Cross-sections of specimens revealed microcracks initiating from the ferritic matrix at the bottom of cavities. Crack propagation into the matrix was impeded by the austenitic islands.