Study On Behaviors Of The Corrosion Of Stainless Steel And Carbon Steel In Circulating Cooling Water

This influence of some important ions including Cl- ,SO42- ,HCO3- and Ca2+ in the circulating cooling water of petrochemical Corperation to the pitting corrosion of stainless steel and the uniform corrosion of carbon steel has been studied by electrochemical test methods (Steady-state polarization curves method, AC impedance method and Potentiostatic polarization method) and Electron microscopy analysis. The inhibition of the inhibitors which has been selected to the pitting corrosion of stainless steel in simulated circulating cooling water has been studied and the effect of the them to the behaviour of uniform corrosion of carbon steel has been discussed.First,effect law of Cl- in the cooling water to the pitting corrosion of stainless steel and the uiform corrosion of carbon steel has been studied . Cl- promotes both the corrosion of stainless steel and carbon steel obviously has been discovered. Then, effect law of SO42- and HCO3- to the pitting corrosion of stainless steel and the uiform corrosion of carbon steel under the condition of Cl- presents. They can inhibit the pitting corrosion of stainless steel but promote the uniform corrosion of carbon steel..There are two results of Ca2+ to both the pittiong corrosion of stainless steel and the uiform corrosion of carbon steel. On one hand,Ca2+ has no obvious influence to the pitting corrosion of stainless steel but can promote the uniform corrosion of carbon steel when HCO3- is absent;On the other hand, Ca2+ can inhibit both the pitting corrosion of stainless steel and the uniform of carbon steel when HCO3- is present.In the simulated circulating cooling water, three inorganic inhibitors A,B and C and an organic inhibitor D has been selected from commonly inhibitors.The experiment results has shown that the inorganic inhibitors A,B and C can inhibit the pitting corrosion of stainless steel in simulated circulating cooling water.The organic inhibition D can also inhibit the pitting corrosion of stainless steel but the inhibition at low temperature is bad. A and D can inhibit the uniform corrosion of carbon steel but B and C does not affect it obviously.