2120 duplex stainless steel（DSS） with and without 0.1% niobium content were prepared by investment casting. The pitting resistance and its influence law of the steel in 3.5% NaCl solution at different temperatures were investigated by electrochemical corrosion methods including potentiodynamic polarization curve test and electrochemical impedance spectroscopy test

combined with optical microscope

scanning electron microscope

and energy spectrum analysis. The results indicate that the stability of surface passivation film of both steels is decreased with the increase of temperature. Meanwhile

the pitting potential is reduced

while the self-corrosion current density is increased. The content of α is increased with niobium-rich phase precipitated in the matrix after Nb addition

and dimension of corrosion hole on the stainless steel surface is expanded with temperature increase.