Comparison Between Stainless Steels and Nickel Alloys Through Pitting Corrosion Resistance Electrochemical Tests

Critical pitting temperature (CPT) is one of the most accepted criteria for alloy classification concerning pitting corrosion. The techniques used nowadays to determine CPT have different parameters for alloys of different material classes, preventing the comparison between stainless steels and nickel based alloys. This study aims to compare the corrosion resistance of nickel based alloys and stainless steels with high corrosion resistance through potentiostatic tests for CPT determination, using a 3M MgCl₂ aqueous solution. CPT values were effectively determined for the stainless steels studied but the technique did not have the same efficiency for nickel based alloys due to the occurrence of crevice corrosion, even considering the higher PRE of nickel based alloys.

Keywords:
CPT; pitting corrosion; high corrosion resistance alloys