Stress corrosion cracking of LDX 2101® duplex stainless steel in chloride solutions in the presence of thiosulphate

• The limits for LDX 2101® duplex stainless steel application in H2S-containing environments.
• The susceptibility to SCC of LDX 2101® duplex stainless steel in the presence of Cl− and SO32-.
• The possibility of substituting H2S with thiosulphate for the study of the SCC susceptibility.
• The selective corrosion of ferrite phase during crack propagation process in the tested media.

SCC behaviour of a LDX 2101® stainless steel was studied through SSRT in a 20% NaCl solution at 80 °C and in the standard NACE TM-0177 solution at 25 °C in the presence of S2O32-. Some tests were also performed in the NACE solution at various pH or temperatures. The LDX 2101® was susceptible to SCC in the presence of small thiosulphate concentrations. The selective corrosion of the ferrite phase became the main cause of failure when the thiosulphate concentration was increased to 0.1 M in the 20% NaCl at 80 °C or when NACE solution temperature was raised to 80 °C.