In the oil sands industry, the erosion-corrosion phenomena are enhanced due to the presence of abrasive solid particles. Thus, in order to prevent failures in engineering components such as pumps and pipelines, corrosion and mainly erosion resistant materials are selected. The white cast irons comprise an attractive candidate for these applications since their hard metallic matrix and chromium carbides can mitigate the erosive attack. However, due to their brittleness and complex microstructure, a careful material selection strategy must be conducted with respect to the operational conditions and, in particular, the size of the erodent particles. In the current study, two white cast irons were evaluated under severe conditions; a 27% Cr alloy (27WCI) with eutectic chromium carbides and another 30% Cr alloy (30WCI) with primary chromium carbides and higher carbide volume fraction than the 27WCI. The evaluation was performed using a submerged jet apparatus in fresh water containing angular silica sand particles with 500 μm diameter on average. Also, the application of cathodic protection contributed to understand the interactions between erosion and corrosion related mechanisms. The most prominent finding was the superiority of the 27WCI alloy over the 30WCI, which was linked to the brittleness of primary carbides and the size of erodent particles.
Key words: Erosion-corrosion, cast irons, impingement, chromium carbides, cathodic protection