| The stress corrosion cracking (SCC) behaviors of Type304austenitic stainless steel in circulating cooling water containing chloride ion were investigated by means of in-situ electrochemical tests under constant strain, slow strain rate tests (SSRT) and scanning electron microscope (SEM). The effect of chloride concentration and strain on SCC was studied and the influence of three water treatment agent on SCC was investigated in simulated hard cooling water. The results of this study were useful for the waste water reuse.The SCC susceptibility of Type304austenitic stainless steel were studied in NaCl solution, low hardness circulating cooling water, middle hardness circulating cooling water, and high hardness circulating cooling water. The stress-strain curve and SEM morphology indicated that the critical chloride concentration scope of SCC in NaCl solution was60mg·L-1～90mg·L-1at60℃. When the chloride concentration was higher then 90mg·L-1, SCC could occur. The critical chloride concentration scope of SCC in low hardness circulating cooling water was300mg·L-1～600mg·L-1at60℃. When the chloride concentration was higher then600mg·L-1, SCC could occur. The critical chloride concentration scope of SCC in middle hardness circulating cooling water was600mg-L-1～800mg·L-1at60℃. When the chloride concentration was higher then800mg·L-1, SCC could occur. The critical chloride concentration scope of SCC in high hardness circulating cooling water was710mg·L-1～1000mg·L-1at60℃. When the chloride concentration was higher then1000mg·L-1, SCC could occur.The effects of strain and chloride concentration on Eb of Type304stainless steel were studied in situ using the electrochemical technology under constant strain. Eb was one of the important parameters for SCC study. The impact factor fε was brought forward to value the effect of strain to Eb quantitatively. The results showed in-siu electrochemical technology was a convenient and reliable method in SCC study reference to the SSRT result.The influence of Rp-98H, Rp-51, Rp-04L water treatment agent on SCC of Type304stainless steel were investigated in simulated cooling water with different hardness grades by means of in-situ electrochemical tests and SSRT. The results indicated that Rp-98H was useless for the inhibition of SCC in low hardness cooling water, whereas Rp-51and Rp-04L were effective inhibitors for SCC of Type304stainless steel in high hardness and middle hardness simulated cooling water. The chemical behaviors within the occluded cell (OC) for Type304austenitic stainless steel in low chloride concentration solution was investigated by means of a simulated OC. The influence of the enrichment of chloride anion on SCC of Type304stainless steel has been studied. It was observed that the amount of chloride anion migrating into the OC was proportional to the charge flowing through the anode. Owning to the effects of enrichment of chloride anion, low chloride concentration in bulk solution could induce SCC for Type304stainless steel. |
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