Effect of Temperature on the Stress Corrosion Cracking of Tempered Type 403 Martensitic Stainless Steel in Sodium Sulfate Solution

Tempered martensitic Type 403 stainless steel has been found to suffer pitting corrosion and intergranular stress corrosion cracking in 0.01 M Na2SO4 at temperatures of 75 and 100 C, but not at the lower temperatures of 25 and 50 C. Significant sulfur (sulfate) contamination of the passive film from solution was found, but the level of contamination could not be correlated with the susceptibility of the alloy to IGSCC. Nonmetallic inclusions (MnS) and carbide precipitates were found to act as nucleation sites for corrosion pits which in turn give rise to IGSCC.