How the multi-phase microstructure of a novel tool steel determines its corrosion behaviour in sulphuric acids
Viktoriia Shtefan, A. Gebert, Martin Hantusch, Kai Neufeld, Josephine Zeisig, Lars Giebeler, Volker Hoffmann, Andreas Undisz, U. Kühn, Julia Kristin Hufenbach
Abstract
The corrosion behaviour of a Fe81Cr15V3C1 steel was analysed compared to commercial X90CrMoV18 (1.4112) in 0.01-1 mol/L H2SO4 solutions. The rapidly cooled steel comprises martensite dendrites, carbide networks (M7C3, MC) and austenite interdendritic areas. Electrochemical measurements with surface analysis (SEM, EDX, AES, GD-OES) revealed the phase impact on corrosion. Active corrosion of austenite occurs at martensite-carbide boundaries leading to narrow bands. A unique oxidation between passivity and transpassivity with dissolution along lamellar carbides and vanadyl(IV) cation release enhances with increasing acid concentration. Both steels exhibit similar corrosion resistance, a superior mechanical performance of Fe81Cr15V3C1 explains its potential for tool manufacturing.