Erosion–corrosion assessment of materials for use in the resources industry

Abstract

The erosion–corrosion properties of a range of ferrous-based materials that are currently being used or have potential for use in the resources industry have been assessed using a slurry pot erosion–corrosion (SPEC) test rig that has the capability of establishing the separate components of erosion, corrosion and synergy. Testing was performed, at 30 °C, in an aqueous slurry containing 35 wt% AFS 50–70 silica sand and a 3.5 wt% NaCl solution. Erosive action was supplied through high-speed rotation of a rubber-lined impeller. Erosion–corrosion performance of materials evaluated was related to composition/microstructure and hardness. Test data correlated with available service experience. The results showed that the cast Cr white irons with (i) a structure that was essentially a duplex stainless steel containing a distribution of hard carbides and (ii) a near eutectic Cr white iron exhibited the highest erosion–corrosion resistance of the materials tested. The evaluation of the Cr white irons also highlighted the influence of Cr and C levels on the E–C properties of these materials. E–C assessment of selected carbon steels confirmed that the erosion-only rates and synergistic levels showed a general decline with increasing carbon content and hardness. As expected, a low C steel pipe product displayed very mediocre erosion–corrosion behaviour as a consequence of its very low intrinsic corrosion resistance and inferior wear properties. This reflected service experience, however, such products are still being used, due to the comparatively low initial cost. A TiC particle-reinforced AISI 316 stainless steel exhibited an almost 45% improvement in the E–C resistance, when compared with an AISI 316L stainless steel.