Corrosion Resistance of High-Strength Austenitic Chromium-Nickel-Manganese Steel Containing Nitrogen

摘要

The corrosion resistance of high-strength Cr-Ni-Mn austenitic steel containing nitrogen and copper is compared with that of Crl8Ni9 and Crl8Ni ION chromonickel steel by means of the Zive MP2 electrochemical system. The polarization curves and electrochemical characteristics of the alloys are determined in general, pitting, and intercrystallite corrosion by various media: aqueous solutions of NaCl (3%); FeCl_3 6H_2O (100 g/L); H_2SO_4 (0.5 M); H_2SO_4 (0.5 M) + injected H_2S; and H_2SO_4 (0.5 M) + KSCN (0.01 M). The corrosion rates are calculated. The results indicate that all the steel samples are corrosion-resistant: they exhibit high resistance to intercrystallite corrosion and also to pitting and general corrosion in chloride-bearing media. No pitting corrosion is observed when Cr-Ni-Mn steel of balanced composition containing nitrogen (and especially steel containing both nitrogen and copper) is immersed in sea water, even when the steel's nickel content is low. This steel outperforms traditional Crl8Ni9 steel in terms of strength and corrosion resistance, even in an acidic medium (0.5 M H_2SO_4).