Failure Analysis on Frature of a Bolt for Steel Construction

The bolt used in a company's outdoor steel construction stair fractured, and means such as macro analysis, chemical composition analysis, metallographic analysis, hardness test and fracture analysis were used to analyze the fracture causes of the bolt. The results show that the fracture of the bolt was mainly due to the fresh surface of the bolt being exposed to the air. Under the combined action of the corrosive environment and stress, cracks initiated at the root of the bolt where the stress was concentrated. The cracks propagated from the outside to the inside and eventually caused a one-time fracture.