Failure analysis of disintegrator beaters

Fatigue failure analysis of two of 36 disintegrator’s beaters is presented. The beaters assembly was fixed on a shaft rotating at 750 rpm. The beater material was low carbon low alloy steel with bainitic structure. The failure analysis was performed on the ground of metallographic examination using light microscopy, scanning electron microscopy (SEM) and estimation of stress concentration using finite element analysis method (FEM). It was found that the fatigue cracking initiation was caused by co-operation of a few factors producing stress concentration: shape and way of fixing that brought the beater edges to cross, asymmetrical support of the beaters in those contact places and transverse machining marks on the beater edges.