Assessment of electrochemical response from high alloy stainless steels during slurry impingement and single impacts to improve understanding of erosion-corrosion

Erosion-corrosion by liquid-solid impact results in damage on high alloy stainless steels where slurries are transported through pipes, valves, and pumps. It is well recognised that this damage is caused by a complex combination of mechanical (impact) and electrochemical (corrosion) processes. The synergy between erosion and corrosion is significant and depends on the nature of the materials and the aqueous environment. As part of a wider study investigating the mechanisms or erosion-corrosion of high-alloy stainless steels, a series of electrochemical tests under multiple particle erosion-corrosion conditions and single impact conditions have been performed. In this paper the electrochemical behaviour under slurry erosion-corrosion and the transient electrochemical response under single impact of three stainless steels (UNS S31254, UNS S32654, and UNS S32750) is assessed. The depassivation and repassivation characteristics of the surface are characterised and these results are discussed in relation to the overall performance of the materials under erosion-corrosion conditions.