The austenitic manganese-chromium steels resistant to stress corrosion cracking

The basic type of MnCr steels (composition 0.05Mn19Cr13) was found to be highly resistant to chlorides. Additions of titanium, niobium and vanadium did not impair resistance to stress corrosion cracking, but addition of nickel in excess of 0.5% appreciably impaired the resistance. The chemical composition of the stabilized steels was selected in such a way as to make the ferrite content as low as possible. The two stabilized steel grades ability to passivate was limited, also because of the presence of manganese; this makes these grades suitable only for less aggressive environments. The ferrite content can be controlled, or the chromium content increased for better corrosion resistance, only by adding another strong austenite-former. Considering the adverse effect of nickel on the resistance to stress corrosion cracking, attention was given to manganese-chromium grade modified with nitrogen and molybdenum.