THE RELATIONSHIP BETWEEN EROSION-CORROSION METAL WASTAGE AND TEMPERATURE

A series of erosion-corrosion (E-C) tests was carried out using 180 mum, angular Al2O3 on 1018, 2.25Cr-1Mo and 2.5Cr-0.55Mo-1.4Si steels (where the compositions are in approximate weight per cent) at different temperatures from 150 to 650-degrees-C at a particle velocity of 2.5 m s-1 which occurs at in-bed locations of bubbling fluidized-bed combustors (BFBCs). Two different relationships between E-C metal wastage and temperature were determined. For the 1018 and 2.25Cr-1Mo steels a peak in the temperature-metal wastage curves occurred at 350-degrees-C. However, for 2.5Cr-0.55-Mo-1.4Si steel below 450-degrees-C the metal wastage was relatively high and constant. Above 450-degrees-C the metal wastage markedly decreased with increasing test temperature. This behavior has been observed on in-bed tubes in BFBCs but has never before been duplicated in laboratory tests. It was found that, in addition to the particle velocity, the corrosion (oxidation) resistance of steels influenced the relationship between metal wastage and test temperature; this is explained in terms of the ductility of the scale that occurred.