Pitting corrosion behavior in novel Mn-N alloyed lean duplex stainless steel containing Cu.

The novel Mn-N alloyed lean duplex stainless steels with different addition of Cu were fabricated and studied in this paper. The effects of Cu addition, solid solution treatments and second phase precipitation on resistance to pitting corrosion were discussed in detail. The addition of 0.5% Cu can significantly improve the resistance to pitting corrosion due to that Cu can increase the activity of alloying Cr and facilitate the diffusion of Cr into ferrite phase, leading to the concentration of alloying Cr in ferrite phase. The corrosion resistance of present steels was decreased with the increase in solid solution treatment temperature from 1000 to 1150 °C due to the increasing difference of pitting corrosion resistivity between ferrite and austenite. The second phase precipitation of CrN can consume the beneficial elements of Cr and N in ferrite, leading to a dramatic decrease in corrosion resistance. The pitting potential of the present steel was sensitive to the aging treatments, and it was continuously decreased with the increase in aging time. [ABSTRACT FROM AUTHOR]