Interpretation of the relation between ferrite fraction and pitting corrosion resistance of commercial 2205 duplex stainless steel

The relation among pitting corrosion resistance, galvanic corrosion rate and phase fraction (44-63 vol% of ferrite phase) of UNS S32205/S31803 duplex stainless steel was investigated. The highest pitting potential was observed in the sample comprising 57 vol% of ferrite, and it decreased with increase in the phase imbalance. In the sample with 57 vol% ferrite fraction, the lowest galvanic corrosion rate between the ferrite and austenite phases was observed. It was found that the pitting corrosion resistance of the alloy samples comprising various ferrite fractions was primarily determined by the galvanic corrosion resistance between the two constituent phases.