Stress Corrosion Cracking of High and Low Strength Carbon Steels in Nitrate Solutions Available to Purchase

Stress corrosion cracking (SCC) behavior in 60% Ca(NO₃)₂, 3% NH₄NO₃ solution boiling at 110 C is reported for relatively pure 1% Ni, 1% Cr, or 1% Ti steels as a function of carbon content. The steels were water-quenched, cold-rolled, or furnace-cooled. Commercial 4140 steel heat-treated to various hardness levels was similarly tested. It was also subjected to SCC in boiling 3% NaNO₃ and boiling 3% NaCl. Critical potentials below which SCC does not occur were measured in 3% NaNO₃ for the latter steel at 4 hardness levels. The results are interpreted in terms of stress-sorption cracking.