Failure Analysis of Drive Head Bolt by Seam Defect

The present work investigates the failure of a bearing cap bolt of a commercial vehicle that suffered a premature failure after running for 1810 kms. Detailed failure analysis has been carried out involving visual inspection, magnetic particle inspection, fractography, microstructural analysis and hardness test. The investigation concludes that the bolt fractured in the shank region due to the presence of seam defect. The crack originated from the seam defect leading to failure of the bolt. It is recommended to emphasize upon adopting best rolling practices pertaining to scale formation and drawing controls for minimization of such defects.