Stress Corrosion Cracking of Stainless Steel Expansion Joint for Heat-Supply Network

Abstract

Tree-like transgranular cracks were found at the bottom of a expansion joint bellow that had been used for heat-supply network at 90°C and 0.8MPa. A failure analysis was conducted, including visual, microstructural, compositional, and mechanical characterization, to determine the cause and source of the degradation. Branched, brittle cracks were observed in the failure region and exhibited transgranular propagation. The results showed that the concentration of the chloride in the deposit was 248 ppm in the intermittent wet/dry cycles situation. It was determined that the likely cause of failure was neutral pH, Concentrated chloride-induced stress corrosion cracking.