Role of segregated P and S in intergranular stress corrosion cracking of Ni

Journal Article · Mon Sep 01 04:00:00 EDT 1986 · J. Mater. Energy Syst.; (United States)

DOI:https://doi.org/10.1007/BF02833343· OSTI ID:6775843

Jones, R H; Danielson, M J; Baer, D R

The effect of P and S on the intergranular corrosion and stress corrosion of Ni has been evaluated with corrosion tests, crack tip corrosion modeling and stress corrosion tests, and modeling. Tests were conducted in 1 N H/sub 2/SO/sub 4/ at 25/sup 0/C over anodic potentials of +0.3 V to 2.0 V (SCE). Corrosion tests were conducted on Ni + P and Ni + S alloys and Ni samples ion implanted with P and S. The corrosion results showed that both P and S reduce passivity in Ni and enhance the corrosion rate but that P is oxidized and dissolves in the electrolyte while S remains on the surface. This difference in surface behaviour of P and S was used to explain the difference in intergranular corrosion (IGC) and intergranular stress corrosion cracking (IGSCC) behaviour of Ni + P and Ni + S. The active crevice and crack walls with Ni + S is thought to reduce the concentration gradient and hence the transport of Ni/sup +2/ from tip to mouth which in turn reduces the crack tip corrosion rate. By comparison of the geometry, potential dependence and rates of IGC and IGSCC of Ni + P it was concluded that IGSCC was not controlled solely by anodic dissolution but that a mechanical contribution was involved. Strain assisted corrosion was ruled out while a corrosion assisted intergranular fracture process was shown to be feasible.

• Research Organization: Pacific Northwest Lab., Richland, WA 99352
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 6775843
• Journal Information: J. Mater. Energy Syst.; (United States), Journal Name: J. Mater. Energy Syst.; (United States) Vol. 8:2; ISSN JMSMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103 -- Metals & Alloys-- Mechanical Properties
360105* -- Metals & Alloys-- Corrosion & Erosion
ALLOYS
CHEMICAL REACTIONS
CORROSION
CORROSIVE EFFECTS
CRACK PROPAGATION
DISSOLUTION
ELECTRIC POTENTIAL
ELECTROLYTES
ELEMENTS
HYDROGEN COMPOUNDS
IMPURITIES
INORGANIC ACIDS
ION IMPLANTATION
MATERIALS TESTING
MEDIUM TEMPERATURE
NICKEL ALLOYS
NONMETALS
OXIDATION
PASSIVATION
PHOSPHORUS
SEGREGATION
STRAINS
STRESS CORROSION
SULFUR
SULFURIC ACID
TESTING