The stress corrosion cracking of C-Mn steel in CO2-HCO3--CO32- solutions .1. Stress corrosion data

The potentials at which intergranular stress corrosion cracking occurs in a mild steel exposed to solutions of various pH values, obtained by varying the concentrations of CO2, HCO3- and CO32- have been determined, as have those potentials at which quasi-cleavage occurs in similar but lower pH solutions. The potential range for intergranular cracking is about 100 mV wide at ambient temperature and extends from pH 6.7 to 11.0, the middle of the potential range falling from about -0.25 to about -0.7 V (SCE) as the pH is increased. Intergranular crack growth rates are reduced by increase in pH and increase with HCO3- concentration of the solution, some data also being collected on the effects of different temperatures. With the lower pH solutions, the different morphology of quasi-cleavage is reflected in a different potential regime for cracking, both suggesting the involvement of a different cracking mechanism. Copyright (C) 1996 Elsevier Science Ltd