Investigation of Conveyor Pulley Shaft Failures

The cause for failures of shafts in a conveyor pulley in iron-making unit at JSW Steel has been investigated. Visual, metallographic, chemical, and fractographic studies were carried out in this study. Fracture studies of the shaft revealed shear failure because of overload. Detailed investigation revealed that the source of overload and cause of failure to be the end disk of the pulley drum, which is not considered a critical component. The disk material complies with the required material specification but failed because of changes in metallurgical characteristics during welding. Severe centerline segregation in the end disk drastically reduced its strength and service life, leading to premature failures. It was found that end disk welding failures led to overloaded bending stresses, thereby causing an imbalance in the shaft rotation and leading to failure.