The Corrosion Resistance of 18Cr-37Ni Austenitic Steel in Alkaline, Acid and Neutral Solutions

Abstract

The corrosion resistance of 18Cr-37Ni steel in HCl, H₂SO₄, NaOH, NaCl and sea water and the effects of heat treatment on the corrosion resistance have been investigated. The alloy offers excellent resistance to corrosion in NaOH up to 100°C. The corrosion resistance in NaCl and sea water is also outstanding. Heat treatment at 900°C for four hundred hours further increases the corrosion resistance in NaCl. The resistance of the alloy in H₂SO₄ and HCl is poor. High current densities are required for passivation in H₂SO₄. The dissolution is generally anodically controlled; however, cathodic control influences the dissolution in NaCl. Pitting has been observed in NaCl in the active state.