Influence of additives in a H2So4 environment on the stress corrosion cracking of type 304 stainless steel

Abstract EN

This study evaluates the resistance of type 304 stainless steel to stress corrosion cracking in sulfuric acid solutions with after addition of potassium cyanate, potassium selenocyanate, decomposition products of cyanate (NH4OH, NaHCOj, or (NH4);C03), and NaOH.

Cracking or localized attacks occurred at sulfate ion concentrations of 1.5-4M and at pH values less than 0.35.

The results show that addition of KOCN, NH4OH, NaHC03, and (NH4)2C03 cause cracking to predominate by inhibiting general corrosion both by neutraliza- tion of some of the aggressive H+ ions and, by adsorption of these species on the metal surface.

KSeCN induces localized attack but inhibits general corrosion, through adsorption.

NaOH induces see by its inhibitive effect decreasing the H+ ion concentration.