Development of wear resistant hammer heads for coal crushing application through experimental studies and field trials

摘要

Coke is one of the most important raw materials for iron making through blast furnace route. Strength and reactivity of coke plays a huge role in efficiency of the counter-current reactor. In order to attain the desired quality of coke, large lumps of coals are crushed in to smaller size fraction in a crushing mill using rotating hammers. However, the heads of these hammers fail prematurely during service that requires their frequent replacements along with interruption in production. This paper presents failure analysis of a coal crushing hammer head with its detailed metallurgical characterization. Analysis revealed that hammer heads fail in abrasive wear mode due to lean chemistry of the alloy used and lower hardness that manifests as higher abrasion rate. 6Cr-1Mo steels were supplied in quenched and tempered conditions to a hardness of around 52 HRC. There was presence of only iron chromium carbides that is not sufficient to withstand an application involving extreme wear.