Galvanic corrosion between the constituent phases in duplex stainless steel

摘要

The exclusive single-phase with the exact chemical composition of the constituent phase in 2205 duplex stainless steel (DSS) could be prepared using selective dissolution method. The respective electrochemical behavior of each constituent phase could then be measured. The experimental results showed that the two distinct peaks in the active-to-passive transition region of the polarization curve determined in 2 M H_2SO_4 + 0.5 M HCl mixed solution were actually corresponded to the respective anodic peaks of the single austenite and ferrite phases. A polarity reversion was found between aus-tenite and ferrite phases in mixed H_2SO_4 + HCl solution and HNO_3 solution. Galvanic current measurements also revealed that austenite was anode in HNO_3 solution, but became cathode when exposed in 2 M H_2SO_4 + 0.5 M HCl mixed solution.