Stress Corrosion Cracking of Steels in CO-CO₂-H₂O Environments

Abstract

The effects of gas composition, alloying elements, cold working and heat treatment on the susceptibility of stress corrosion cracking of mild steels, low alloy steels and austenitic stainless steel in CO-CO₂-H₂O environments have been investigated.
The results obtained are summerized as follows:
(1) The transgranular stress corrosion cracking occured in CO-CO₂ environments which are consisted of both vapor and liquid phase. Stress corrosion cracks initiated from pits on the surface of specimens in liquid phase.
(2) The resistance of the killed SS41 steel to stress corrosion cracking is superior to the rimmed SS41 steel. The Cr-Mo steels containing Cr more than 9% did not suffer from stress corrosion cracking in CO-CO₂ environments.
(3) The susceptibility of these steels to stress corrosion cracking was increased with increase of hardness due to heat treatment.
(4) Mild steels are more susceptible to stress corrosion cracking at 5% cold working than at other cold working conditions.