Influence of particle impact conditions and temperature on erosion–oxidation of steels at elevated temperatures

The behaviour of four steels that are used in fluidized-bed boilers (16Mo3, T91, 304L and 253MA) has been studied in air (oxidation) and under impacts by sand particles in air (erosion–oxidation) at 350–650 °C in an extensive test programme and their performance compared in terms of the resulting weight changes and surface appearances. The results show that the oxidation rates for the steels increase with temperature but decrease with increases in chromium contents of the steels, as expected. Through oxidation rate, temperature has a significant influence on overall weight changes during combined erosion–oxidation, with material losses often increasing with temperature. The lowest particle velocities often cause deposition of particle debris and some weight gains, whereas the highest velocities cause essentially loss of material. Ductile erosion behaviour is observed under most conditions, with higher material losses at a shallow than at a steep impact angle, but the overall angle-dependency slightly changes with increase in temperature. The explanations for these observations are discussed in this paper. Furthermore, materials selection maps are constructed from the results generated, demonstrating that choosing the most highly alloyed material available is not necessarily the best rationale for materials selection.