Failure analysis of stress corrosion cracking in aircraft bolts

This research was conducted on the failure analysis of the failed clamp bolt from a helicopter engine in the RoKAF. Through the fractography, metallography, and stress analysis of the failed part, it was found that the clamp bolt was fractured by stress corrosion cracking due to the interaction of tensile residual stress and corrosive environment. The stress corrosion crack is a phenomenon that occurs in susceptible alloys and is caused by the conjoint action of a surface tensile stress and the presence of a specific corrosive environment. Therefore, it is recommended that the material of the clamp bolt should be changed to prevent similar failures.