Corrosion of ferritic and ferritic-martensitic steels in NaCl-KCl-VCl 2 melts

Abstract

The corrosion resistance of ferritic (08Kh17T) and ferriticmartensitic (12Kh13) type steels was investigated at 750 °C in NaCl-KCl-VCl2 melts. The mechanism of corrosion of 12Kh13 ferritic-martensitic steel in NaCl-KCl-VCl2 melts includes two parallel processes: formation of new excessive phases inducing Fe3C (σ-phase)|melt|steel microgalvanic pairs, and reaction of most electronegative steel components (Mn and Cr) with V3+ ions formed due to disproportion of V2+. Contacting samples of 08Kh17T with NaCl-KCl-VCl2 melts resulted in no structural changes in the steel samples. In this case the mechanism of corrosion involves only one stage: disproportion reaction of V(II) with the formation V-Fe alloy and V3+ ions and further oxidation of chromium in the steel by V(III). It was shown, that the presence of a suitable reducing agent in the contact with the melt (for example, metallic vanadium) can prevent the steel destruction. Copyright © 2012 by The Electrochemical Society.