Fracture Failure Analysis of Stainless Steel Pipe in a Liquid Hydrogen Transport Vehicle

In order to find the reasons for cracking of stainless steel pipe in a liquid hydrogen transport vehicle, a series of analysis were conducted for the cracks and fracture surface in terms of macro and micro morphology, chemical composition, corrosion products and metallurgical structure. The results show that high carbide content in flange material and repeated heating of weld heat affected zone (HAZ) because of welding repair were the reasons which caused carbide precipitation along grain boundaries and thus led to the decrease of intergranular corrosion resistance. And then a brittle delay fracture happened to the stainless steel pipe in a chloride and stress environment. It was suggested that the stress corrosion (SC) in the HAZ of stainless steel welded joint must be prevented in aspects of design, material selecting, construction, surface modification and monitoring.