This review article on delayed fracture of bolts covers the following topics: general features of delayed fracture, case histories of in-service failures of high-strength bolts, existing demands for higher-strength bolts and their background, increasing needs for standardization of delayed fracture susceptibility evaluation method, and approaches so-far taken to prevent delayed fracture. The author emphasizes that, thanks to the recent intensive R&D activities, overcoming delayed fracture is now very close to the reality.
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