Influence of artificial seawater on the cyclic response of superduplex stainless steels

Superduplex stainless steels (SDSSs) are a family of alloys originally designed to resist corrosion in seawater. The aim of this work has been to study the low cycle fatigue behaviour of a SDSS in air and in artificial seawater. Three different plastic strain amplitudes corresponding to distinct positions on the cyclic stress-strain curve were selected in order to compare the number of cycles to failure in both environments. The results showed a remarkable reduction in fatigue life in the presence of the aqueous solution, especially for high strain amplitudes. These experimental findings are rationalised considering the different mechanisms governing the corrosion fatigue process as a function of the plastic activity developed by the ferritic phase.