Effect of U-bending deformation on pitting corrosion of 2205 duplex stainless steel under wet-dry cycling of chloride salt droplets.

The pitting behavior of 2205 duplex stainless steel after U-bending deformation was investigated under wet-dry cycling of droplets. At the tensile side, the average critical relative humidity for pitting (RH pit) was increased from 44.5% to 55.6%, the critical relative humidity (RH rep) for repassivation was correspondingly increased from 59.9% to 76.6%. The compressive strain increased the critical relative humidity to 52.9% (RH pit) and 73.3% (RH rep), respectively. Compared to the hemispherical pits without deformation, selective dissolution of the ferrite phase with irregular pits appeared on the tensile side. The decrease in pitting resistance and the formation of irregular pit morphology were discussed. • In-situ potential monitor and EIS analysis proved pitting under droplets on U-bent 2205 DSS. • Both tensile and compressive strain decreased the critical chloride content for pitting. • The pit probability increased on both the tensile and compressive strain sides. • The pit morphology on the tensile strain side was irregular with micro-cracks. • The pits on the compressive strain side present as shallow round-type morphology. [ABSTRACT FROM AUTHOR]