ANODIC BEHAVIOR OF NICKEL BASE ALLOYS IN MEDIA CONTAINING BICARBONATE AND CHLORIDE IONS.

NATALIA S. ZADOROZNE; RICARDO M. CARRANZA ; MABEL C. GIORDANO; ALICIA E. ARES; RAUL B. REBAK

Salt Lake City, Utah, USA.

Conferencia; NACE CORROSION 2012; 2012

NACE CORROSION

The simultaneous presence of bicarbonate and chloride ions may be necessary to inducestress corrosion cracking (SCC) in alloy 22 at anodic applied potentials. It has been suggestedthat the susceptibility to SCC could be related to the occurrence of an anodic peak in thepolarization curves below the transpassive range. The aim of this preliminary work is to studythe anodic behavior of alloy 22 and three other nickel alloys in different media containingvarious concentrations of bicarbonate and chloride ions as a function of the temperature todetermine which element in the alloy maybe be responsible for the anodic peak and/orcracking. The studied materials included alloys 22, Ni-201, alloy 800H and 600. Results showthat for alloy 22 the potential and the peak current increased with the temperature and chlorideconcentration in the solution. For the alloys with smaller alloying content the peak potentialdecreased to the point of disappearing. There was no dependence of the current of the peakwith the amount of alloying. In a future work, slow strain rate tests will be performed todetermine if there is correspondence between SCC and the presence of the anodic peak.