Erosion-corrosion assessment in strong acidic conditions for a white cast iron and UNS S31600 stainless steel

ABSTRACT In mining industry, various parts of pumps such as liners and impellers are deteriorated severely due to erosion-corrosion mechanisms reducing the productivity of mining process and the transportation of extracted ores. It has been found that some mines consist of chlorides, very low pH and abrasive erodent particles which enhance the materials degradation. Two groups of alloys that are attractive for those aggressive slurries are white cast irons and stainless steels. In the present study, the erosion-corrosion performance of a hypoeutectic white cast iron with austenitic matrix (37 WCI) and UNS S31600 stainless steel was investigated. The testing apparatus used submerged jet technique and the angle of impingement was the normal incidence. The tests in solid/liquid impingement were conducted in aqueous solution with 3.5% NaCl with silica angular sand at pH 0. The results revealed that 37WCI was superior to UNS S31600, whilst the proportional damage of pure erosion, pure corrosion and their synergistic effects were investigated thoroughly. Detailed analysis was obtained by implementing cathodic protection (CP), potentiodynamic techniques, surface topography and microscopy. The erosion-corrosion phenomena were also analysed in different regions of the tested surface in order to understand how they affect the materials’ performance in different hydrodynamic zones. It was found that corrosion was a crucial factor for the alloys’ performance, rather than their wear resistance. In addition, both alloys experienced higher corrosion rates in regions where the mechanical damage was enhanced.