Fatigue Fracture of Cast Steel Plate Connected in a Power Transmission Joint Assembly

A cast steel plate (flange) connected in a power transmission joint of a drawing machine was fractured after one year of operation leading to unexpected production line interruption and machine downtime. A broken piece of the plate was submitted for material characterization and subsequent failure investigation. Metallurgical investigation was performed to identify the construction material and evaluate the principal fracture characteristics related to failure mechanisms. The findings of the investigation suggested that the failure occurred because of the operation of multiple-origin fatigue, initiated at high stress concentration sites, such as bolt hole connections and keyways. Fractography, optical metallography, and microhardness testing were used as the principal analytic techniques of the present investigation.