Fracture Causes of Stainless Steel U-bolt

A S30408 stainless steel U-bolt fractured after about 0.5 years of use. The fracture causes of the U-bolt were analyzed by means of chemical composition analysis, hardness test, tensile test, metallographic examination, non-metallic inclusion test, fracture analysis and energy spectrum test. The results show that the S30408 stainless steel U-bolt produced residual stress during cold work hardening, then superimposed the working stress. In addition, the stress corrosion cracking of the bolt occurred in humid corrosive environment, and the crack continued to expand, which eventually led to the fracture of the U-bolt.