The susceptibility of 90Cu-10Ni alloy to stress corrosion cracking in seawater polluted by sulfide ions

Journal Article · Fri Aug 01 04:00:00 EDT 1997 · Journal of Materials Engineering and Performance

DOI:https://doi.org/10.1007/s11665-997-0126-9· OSTI ID:540937

El Domiaty, A; Alhajji, J N ^[1]

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1. Kuwait Univ, Safat (Kuwait)

Electrochemical polarization measurements and slow strain rate tests (SSRT) of a 90Cu-10Ni alloy in highly sulfide polluted seawater were conducted to investigate stress-corrosion cracking (SCC) behavior. The severity of the SCC depends on the sulfide concentration in the seawater. The severity increases as the concentration increases. Because the major time in SCC is spent in the initiation process of the propagating crack, the fracture toughness has only a minor effect in the component life failed by SCC. The SCC behavior of CDA706 is strictly linked to sulfide concentration in the range of 100 to 1000 ppm. The general corrosion of Cu-Ni alloys in low (<100 ppm) and high (>100 ppm) sulfide polluted seawater increases due to the selective copper dissolution. Cyclic polarization measurements confirmed that the corrosion rate decreases slightly as the sulfide concentration increases. Pitting tendency was high in the low concentration range of sulfide and low in the high concentration range. The presence of stresses in SCC removes the protective layer as it increases during testing of the specimen or during the actual service of a component. The authors propose that film rupture occurred, and two proposed SCC mechanisms were operational, namely sulfide stress cracking associated with the anodic dissolution in the low sulfide concentration range and hydrogen embrittlement, which was dominant in the high sulfide concentration range. It was found that a synergism exists between sulfide and stress that enhances the effect of the latter.

• Sponsoring Organization: USDOE
• OSTI ID: 540937
• Journal Information: Journal of Materials Engineering and Performance, Journal Name: Journal of Materials Engineering and Performance Journal Issue: 4 Vol. 6; ISSN 1059-9495; ISSN JMEPEG
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COPPER BASE ALLOYS
CRACK PROPAGATION
CRACKS
FRACTURE PROPERTIES
HYDROGEN EMBRITTLEMENT
NICKEL ALLOYS
PITTING CORROSION
SEAWATER
STRAIN RATE
STRESS CORROSION
SULFIDES