The current work evaluated the role of chlorides in stress corrosion cracking (SCC) of standard grade
UNS 32205 (2205) and lean grade UNS 32101 (2101) duplex stainless steels (DSSs) in a hot alkaline
sulfide solution of 150 g/L sodium hydroxide (NaOH) and 50 g/L sodium sulfide (Na2S). Constant
extension rate testing (CERT) was conducted in an autoclave at 1700C at an initial strain rate of 2 X 10-6. Test solutions contained 0, 0.5, 2, 5, 10, 20, and 100 g/L sodium chloride (NaCl). The fracture
morphology was characterized using scanning electron microscope (SEM) equipped with an energy
dispersive spectrometer (EDS). The fracture surfaces were mounted and observed under an optical
microscope and the crack size and distribution was evaluated for the transverse (T) and normal (N)
directions. A significant change in fracture morphology is observed when chlorides are added to
alkaline sulfide solution. Chlorides enhance selective dissolution of the austenite phase in intermediate
concentrations (0.5–10 g/L). A higher concentration of sulfide and nickel were present in the passive
film for these concentrations. An increase in ductility is observed for higher concentrations (10–100 g/L)
of chloride in 2205 DSS owing to higher dissolution rates of both the austenite and ferrite phases. More
severe SCC is observed in 2101 DSS at higher concentrations (10-100 g/L) of chloride.
Keywords: 2101, 2205, CERT, duplex stainless steel, chloride, sulfide, selective dissolution