Effects of Temperature and Anion-species on the Susceptibility to Chloride Stress Corrosion Cracking of Stainless Steels in Hot Water

Abstract

The combined addition of Si and Cu is effective in order to improve the stress corrosion cracking SCC resistance in hot water environment, and SUS315J1 18Cr-10Ni-1.5Si-1Mo-3Cu has been developed and put in practical use. But, the preset temperature of equipments for supplying hot water in recent years has tended to become high near 100. Moreover, the influence of anion-species included in hot water on SCC has not been confirmed yet. The SCC resistance of various stainless steels was examined by the immersion test using spot-welded specimens in 200 mg/L Cl solution at 60, 95 and 125. The materials used were SUS304, SUS315J1, SUS316 and SUS444 cold-rolled steel. SUS315J1 showed the good SCC resistance compared with SUS304 and SUS316 at a temperature under 95. The influence of various anion-species NO 3 , SO 4 2 , CO 3 2 and HCO 3 on SCC was considered by the immersion test or electrochemical measurement in 200 mgL 1 Cl solution. These anion-species that generally act as a corrosion inhibitor performed as accelerator on SCC initiation in addition of a small amount of anions. However, SCC tended not to occur in SUS315J1 in these solutions.

Study of effectiveness of heavy metals ions as the inhibitors of steel corrosion

“…This water is characterized by a low concentration of chlorides and sulfates, other indicators do not exceed the norms [16]. To some extent, anions can affect the process of corrosion [17], which is why this fact was taken into account when processing the results. Characteristics of tap water iare given in Table 1.…”