Studies on the degree of sensitization of hyper-duplex stainless steel 2707 at 900℃ using a modified DL-EPR test

Abstract The effects of thermal aging of hyper-duplex stainless steel (HDSS) 2707 at 900℃ for various aging times up to 26 h on the localized, selective corrosion were investigated by electrochemical methods. The results demonstrate that the optimum test condition is 2 M H2SO4 + 1.25 M HCl + 0 .001 M KSCN with the scan rate of 1.5 mV·s-1 at 30℃. The degree of sensitization (DOS) of HDSS 2707 initially increases rapidly, because of particle precipitation (σ phase/Cr2N), and then decreases as a result of self-healing by back diffusion of Cr and Mo into the depleted areas, peaking at 10h.