ステンレス鋼の高温水中臭化物応力腐食割れ Bromide Stress Corrosion Cracking of Stainless Steels in High Temperature Water
Bromide stress corrosion cracking (Br<sup>-</sup> SCC) of stainless steels has not been clear, owing to many unknown factors, however troubles caused by it have been reported in MSF desalination plant. In this study, environmental factors, materials and surface treatments of noble metals plating have been investigated in order to protect Br<sup>-</sup> SCC in bromide containing high temperature water. SCC tests have been conducted by using slit-welded type specimens. The results are summaried as follows: (1) Concentration of disolved oxygen must be kept below 0.1ppm for protection of Br<sup>-</sup> SCC. (2) Transgranular SCC due to pitting occurs in SUS 304 and SUS 316 stainless steels above 50ppm Br<sup>-</sup> concentration. (3) The number of SCC is more major in Cl<sup>-</sup> environment than in Br<sup>-</sup> one above 0.5ppm disolved oxygen concentration. (4) Occurrence percentage of growing SCC is much higher in Br<sup>-</sup> environment than in Cl<sup>-</sup> one in all disolved oxygen concentration. This fact shows that Br<sup>-</sup> SCC, especially in chemical plants, grows so large that contents leak. (5) Hastelloy C 276 is most completely resistant materials in heavily severe Br<sup>-</sup> environment. (6) Only Rh in noble matal platings is the most effective to resistantly protect Br<sup>-</sup> SCC. But the reason has not been clear in this study.
- 材料と環境 : zairyo-to-kankyo
材料と環境 : zairyo-to-kankyo 45(5), 284-291, 1996-05-15
Japan Society of Corrosion Engineering