Corrosion potential of corrosion resistance alloys (as indicated) freely exposed to natural seawater. The sharp step increase is caused by biofilm formation. Nomenclature: 25 Cr SDSS: UNS S32750 super duplex stainless steel, Titanium: UNS R50400 titanium grade 2, NAB: nickel aluminum bronze, and 254SMO: UNS S31254 6Mo austenitic stainless steel. CC BY-NC-SA 3.0