Electrochemical Behavior of Different Weld Areas of Stainless Steel in Nitric Acid

The corrosion electrochemical characteristics of the materials from different areas near the weld in nitric acid solution were studied through the testing of polarization curves and electrochemical impedance spectroscopy (EIS). The results show that the corrosion current density increased and the reaction resistance of surface passivation film reduced after stainless steel sensitization. The corrosion current density and surface reaction resistance of the non-sensitized areas of the weld had few differences. The corrosion resistance of weld metal was better than that of the sensitized area, but worse than that of the non-sensitized area. Intergranular corrosion didn't occur in the areas of No. 1, 3, 5 and 7, which showed a single capacitance arc in Nyquist diagram, and each resistance value was close. Serious intergranular corrosion occurred in the area of No. 6, whose Nyquist diagram presented two capacitive arcs, and the polarization resistance of this area was significantly less than that in othe ther areas.