Effect of Microstructure Ferritization on Pitting Corrosion Resistance of 2507 Duplex Stainless Steel

The effect of microstructure ferritization on pitting corrosion resistance of 2507 duplex stainless steel was studied by JMatPro material performance simulation software, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and electrochemical testing. The results show that after the solution treatment at 1 050-1 250℃ for 60 min ferritization happened in the microstructure of 2507 duplex stainless steel, resulting in the increase of Gibbs free energy of austenite phase. With the increase of solution treatment temperature, the content of ferrite increased, but the rate of ferritization decreased. The ferritization of microstructure led the chemical element content of two phases change obviously, that is, the content of Cr and Mo of in ferrite phase decreased, while the content of Ni and N in austenite phase increased. When the content of ferrite phase with weak corrosion resistance increased, the resistance of passive film and corrosion hole of 2507 duplex stainless decreased rapidly, the corrosion current density increased, and the pitting corrosion resistance decreased rapidly.