High-temperature Corrosion Investigations of Deposit Containing Eutectic KCl-K2SO4 Mixture on AISI 1015 and SS304 Steels

This study investigated corrosion behaviours of biomass fly ash containing eutectic KCl-K2SO4 mixture on carbon steel AISI 1015 and stainless steel 304 (SS304) at 700 degrees C for 12 h in air. The observed corrosion behaviours were validated by comparing with corrosion on similar materials, including carbon steel STBA 12 boiler tube and SS304 erosion guard, exposed in actual boiler environments. Similar corrosion behaviours were found in both laboratory-scale and field tests. Active oxidation, caused by chlorine, dominated over internal sulfidation for carbon steels. For SS304, presence of chlorine depleted protective oxide layers of SS304, followed by internal sulfidation from sulphur species.