| Local corrosion behavior of 304 stainless steel (304 ss) in circulating cooling water of low and high hardness with Cl- was studied by potential dynamic scanning polarization technique , electrochemical impedance spectroscopy (EIS) technique , in-situ electrochemical tests under constant strain and energy dispersive spectrometry (EDS). The anodic polarization behaviors of 304 ss in NaCl, Na2SO4+NaCl solution and simulated hardness cooling water were studied by potential scanning technique. Potential dynamic scanning polarization technique, electrochemical impedance spectroscopy technique and in-situ electrochemical tests under constant strain were applied to study the influence of the temperature, water treatment agent and stress to the corrosion sensitivity.The results showed that under the test condition, as a kind of corroding ion Cl- decrease the pitting potential and pitting potential increased with the adding of SO42- . If Cl- = 0, SO42- concentration had no effect on Eb. In solution of same Cl- concentration, pitting corrosion potential in simulated low hardness circulating cooling water was more negative than what in solution of high hardness. And it indicated that 304 ss has stronger corrosion sensitivity in solution of low hardness circulating cooling water. The inhibition efficiency of RP-98H is 84.8%. RP-04L has good anti-scaling effect whose efficiency is 70.93% to 304 ss in the high hardness circulating cooling water at 60℃. Potential dynamic scanning polarization and electrochemical impedance spectroscopy (EIS) results showed that 304 ss has stronger corrosion sensitivity with stress than without. The value of pitting corrosion sensitivity was increased with temperature in low and high hardness circulating cooling water.
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