Comparative study of erosion-corrosion performance on a range of stainless steels

Erosion-corrosion is one of the most severe types of material deterioration that occur in hydraulic machinery. Corrosion resistant alloys perform well in some marine applications. These materials do have their limitations, though, and for this reason a comparison of their performances is significant. This study focuses on the assessment of the relative behaviour of four different types of stainless steel (UNS S31600, UNS S32760, UNS S42000, and UNS S17400) in erosion-corrosion environments. The study was expanded to include a carbon steel (UNS G10400). Test pieces have been investigated in a submerged jet impingement apparatus in 3.5% NaCl solution with suspended solid particles at temperatures of 30-35 °C. In situ corrosion monitoring was also undertaken and the influence of the application of cathodic protection was studied. This facilitated assessment of the relative roles of erosion, corrosion and synergy on the overall degradation processes. A variety of examination techniques were utilised (i.e. mass loss, surface profiling, microscopy) in order to obtain detailed information on those different modes of attack. Differences between stainless steels and carbon steel were observed and the superduplex stainless steel exhibited the best performance of the four types of stainless steel investigated herein.