Failure Analysis of a Chain Link Used in Charger Drive of a Coke Oven Battery

Abstract

Failure analysis of a chain link of charger drive in a coke oven battery has been presented. The chain facilitates the charging of stamped coal cake (about 25 tons) into the oven through charger plate with its drive mechanism. The chain failed during service due to the breakage of a pair of link plates from the pin-hole location. The failure investigation consists of visual observation, fractography, compositional analysis, microstructural characterization, scanning electron microscopy, energydispersive spectroscopy (EDS), and mechanical characterization like hardness, tension, and impact tests. Fractography confirmed initiation of fatigue crack (primary failure) from a surface defect present at the edge of the pin hole; other fracture surfaces exhibited brittle nature. Microstructural examination and EDS analysis at the location of surface defect on the link plate reveal the presence of manufacturing defect which originated at slab stage in the casting-rolling route of plate manufacturing. The link plates are made by slitting of plates manufactured via hot rolling of steel slabs. The presence of grain boundary as well internal oxidation suggests that the defect originated at the slab stage before hot rolling.