Heat resistant steel casting for pallet sidewalls in an iron ore pellet induration plant

摘要

Pallet sidewall castings in five different heat-resistant alloys were field tested at the Iron Ore Company of Canada's iron ore pellet induration plant. Performance of four new alloys—HL, HP, HU and Haynes Alloy A230—were compared with thetraditional HH alloy after a period of 24 months in service. The alloys were visually ranked from best to worst.The "new" alloys were considerably better than HH. Alloys having high chromium, with the exception of HH, seemed to perform the best. Surprisingly, alloys high in nickel content did not fare as well. Later, metallographic examination revealed extensivemicrovoid formation in the interior of the heat-affected areas of HH, HL and HP. The tendency for microvoid formation decreased with increasing nickel content in HU and A230. HL and HP may be prone to catastrophic failure during service. In summary,chromium imparts resistance to surface degradation, while nickel imparts resistance to internal microvoid formation.