Abstract: The SCC susceptibility of the plastically pre-deformed 18-5-Nb duplex stainless steel to lo- calized corrosion was evaluated in both 25% NaCl+1% K_2Cr_2O_7 and 42% MgCl_2 boiling so- lutions.The y phase in the steel is metastable at room temperature and the γ-α′ martensitic transformation can be induced by cold plastic deformation.With the increase in cold deformation,the volume fraction of α′ martensite increases.Cold plastic deformation results in a remarkable deterioration of SCC resistance of the steel in chloride-containing solutions, resulting from the decrease in corrosion resistance of γ phase in the duplex.It is indicated that, in NaCl solution,the SCC in 18-5-Nb duplex stainless steel initiates at pits and the selective attack on γ phase plays a significant role in the initiation and propagation of SCC.

Key words: duplex stainless steel, plastic deformation, stress corrosion cracking