Alloy 22 (N06022) is a nickel base alloy highly resistant to all forms of corrosion. In aggressive
environmental conditions Alloy 22 could suffer localized attack such as crevice corrosion. For a given
application, the occurrence of localized corrosion is governed by the values of the critical potential
(Ecrit) for crevice corrosion and the corrosion potential (Ecorr). If by natural evolution Ecorr may reach potential
values in the order of Ecrit, localized corrosion may be expected. The objective of this work was
to study the metallurgical effect of Alloy 22 on the corrosion potential in a variety of electrolyte solutions.
The Ecorr of Alloy 22 was monitored as a function of time for non-welded (or mill annealed –
MA), as-welded (ASW), and as-welded plus high temperature aged (HTA) rods. The six different electrolyte
solutions studied included acidic and alkaline, reducing and oxidizing, detrimental and nondetrimental
for crevice corrosion. In general the HTA rod established the highest Ecorr followed by the
ASW and the MA rods. The higher Ecorr of the HTA materials was attributed to the presence of second
phase topologically close packed (TCP) particles. This hypothesis needs to be confirmed by further testing.
Keywords: N06022, corrosion potential, mill annealed, as-welded, high temperature aged