LAUSR

Abstract Grate plate is one of the consumable components of chain grate in pelletizing plants, which is made up of heat resistant stainless steels. Service life of grate plates has major effect on productivity and quality of pellets. Objective of this work is to study the mechanism of intergranular cracking in heat-resistant stainless steel, one of the major degradation mechanisms of grate plates, in order to suggest preventive methods. To reach this goal, plant samples were provided from used and as-cast grate plates. The samples were studied using a scanning electron microscope (SEM) equipped with an energy dispersive x-ray spectroscopy (EDS) probe and metallography techniques. The results revealed that no Cr-depletion zone was formed during solidification and also during using of the grate plates at elevated temperatures. It was also revealed that formation of interdendritic Mn, S and/or C concentrated precipitates is the reason of the intergranular crack nucleation and propagation during the service time. As a solution to prevent that defect, it is suggested to reduce the distance between the liquid impenetrable temperature (LIT) and solidus temperature during solidification (for example with decreasing the concentration of S content).