Localized Corrosion Behavior of Ferritic and Austenitic Passive Materials

NATALIA SILVINA ZADOROZNE; RAÚL B. REBAK

Congreso; NACE 2017; 2017

Stainless steels (SS) arethe workhorse alloys of aggressive industrial applications. Stainless steelsare obtained by adding chrome into iron alloys.  Other elements such as molybdenum are alsoadded to increase the resistance of these alloys to localized corrosion.  Stainless steels may exist as ferritic,austenitic, martensitic and duplex materials.  Localized corrosion of SS is generallypromoted by chloride ions (Cl-) in localized spots of a passivated metalsurface.  This paper shows resultscomparing the localized corrosion resistance of seven martensitic, ferritic andaustenitic stainless steels in deaerated 10,000 ppm Cl- solution atambient temperature.  Results show thatin general the resistance to localized corrosion correlates well with the valueof the pitting resistance equivalent number (PRE), regardless of theircrystalline microstructure (i.e. austenitic vs ferritic).