Chloride Content Effect on the Corrosion Fatigue Properties of Superduplex Stainless Steels

Abstract

The corrosion fatigue performance of a superduplex stainless steel in two different chloride-bearing solutions (30g∕l and 60g∕lNaCl) is explored in the present paper. Fatigue life results and surface damage analysis show a strong influence of the applied strain amplitude, as well as of the chloride content, on the cyclic response. Moreover, there is an interaction between both factors because corrosion fatigue mechanisms at low and high strain amplitudes are not comparable, since ferrite is only fully plastically active at high strains. Whereas a detrimental effect of the 30g∕lNaCl solution on the fatigue strength is observed, longer fatigue lives were attained in 60g∕lNaCl solution, even longer than in air. Surface damage inspection and residual solutions analysis support a critical anodic dissolution rate, which would act as a polishing effect, as the main reason for this unexpected result.