Sulphide-induced stress corrosion cracking and hydrogen absorption of copper in deoxygenated water at 90°C

Antti Forsström*, Richard Becker, Hannu Hänninen, Yuriy Yagodzinskyy, Heikkilä Mikko

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

Stress corrosion cracking (SCC) of oxygen-free phosphorous-alloyed copper was investigated in sulphide- and chloride-containing deoxygenated water at 90°C with sulphide concentrations of 0.001 and 0.00001 M. Several intergranular defects were found in the specimen exposed to the high sulphide environment. Similar defects were not found in the low sulphide environment, where only slight corrosion on grain boundaries and slip lines occurred. Hydrogen content measurements show an increase in hydrogen uptake of the plastically deformed specimens, which is dependent on the sulphide concentration and on plastic deformation of copper. However, the highest hydrogen content was measured in friction stir welds, welded in air without shielding gas, and tested in the high sulphide environment. The embedded oxide particles in the weld metal act as local hydrogen trapping sites and selectively react with the sulphide solution. A relatively thick air-formed oxide film covers the copper canisters when deposited, which transforms into a sulphide film in the repository conditions. Thus, some of the coupon specimens were pre-oxidised. The conversion of the pre-existing Cu2O film into Cu2S film occurs quickly and the transformation is almost 100% efficient. The structure and properties of the Cu2S films, susceptibility of copper to sulphide-induced SCC and hydrogen uptake of copper in reducing, anoxic repository conditions are discussed.

Original languageEnglish
Number of pages16
JournalMaterials and Corrosion
Early online date29 Jun 2020
DOIs
Publication statusE-pub ahead of print - 29 Jun 2020
MoE publication typeA1 Journal article-refereed

Keywords

  • copper
  • hydrogen absorption
  • stress corrosion cracking
  • sulphide corrosion

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