Pitting Corrosion Behavior of Stainless Steel Plate Used for Steel Liner of Nuclear Power Plant in Boric Acid Solution

The effects of temperature, Cl^- content and SO₄^2- content on pitting behavior of S30403, S32101 and S32205 stainless steel plates in boric acid solution were studied by electrochemical methods. The results show that pitting potential (E_b) and repassivation potential (E_r) of those three materials declined when increasing the content of Cl^-, pitting potential and repassivation potential of S32205 stainless steel were higher than those of S32101 and S30403 stainless steels. A critical temperature (about 60℃) existed, when the temperature was higher than the critical temperature, the pitting potential decreased obviously. Critical temperature for repassivation potential was in the range of 40~60℃. The effect of the content of SO₄^2- on pitting potential and repassivation potential for three materials was little. The pitting corrosion resistance of S32205 stainless steel is more excellent than that of S30403 and S32101 stainless steels in different experimental conditions, while the pitting corrosion resistance of S30403 and S32101 stainless steels is equivalent.