Stress corrosion cracking of L360NS pipeline steel in sulfur environment

Slow strain rate test (SSRT) and tensile fracture observation are applied to study the stress corrosion cracking (SCC) of L360NS pipeline steel. 5.0 wt. % sodium chloride solution containing elemental sulfur and 0.5 wt. % glacial acetic acid solution containing elemental sulfur are used. The results show that brittle fracture mainly occurs on the samples in high sulfur environment. In the sulfur suspension solution, the SCC sensitivity of L360NS pipeline steel increases along elemental sulfur content. In sulfur melting cladding condition, obvious corrosion can be observed with a large amount of corrosion pits appearing on the gauge section of the sample. The corrosion products are Fe1+xS, black easily detached, and H2. In sulfur suspension and sulfur melting cladding conditions, stress oriented hydrogen induced cracking (SOHIC) is the main cracking, which is caused by the joint effect of SCC and hydrogen induced cracking (HIC).