Analysis on Fracture Reason of Pressure Relief Valve Rod of F304 Stainless Steel

The fracture reason of pressure relief valve rod of F304 stainless steel was investigated by macroscopic inspection, metallographic examination, fracture analysis and so on. The results showed that the fracture of rod belonged to stress corrosion cracking. Cracks initiated from the inner surface of rod center hole and expanded to outer surface of rod. The cracking reason was that pressure relief valve rod had not been heat-treated for solid solution after cold working and led to a large number of strain induced martensite structure appeared in austenite stainless steel. There was corrosive substance including sulfur in natural gas. Hydrogen embrittlement stress corrosion cracking occurred in pressure relief valve rod.