Fracture Analysis of Stainless Steel Bolt

A stainless steel bolt of the clamp of an aircraft oil pipeline fractured after serving for a while. The failure mode and cause of the bolt were analyzed by macro and micro observation, chemical composition analysis, energy spectrum analysis. hardness testing and metallographic examination. The results show that the fracture mode of the bolt is stress corrosion. The co-effect of environmental media and work stress led to the stress corrosion fracture of the bolt at the T root, where stress concentration existed. Improper heat treatment led to abnormal microstructure and high hardness, which increased the susceptibility to stress corrosion and promoted the fracture of the bolt.