Hydrogen pressure dependence of the fracture mode transition in nickel

Journal Article · Mon Aug 01 04:00:00 EDT 1983 · Metall. Trans., A; (United States)

DOI:https://doi.org/10.1007/BF02654401· OSTI ID:6554194

Jones, R H; Baer, D R; Bruemmer, S M; Thomas, M T

A relationship between fracture mode, grain boundary composition, and hydrogen pressure has been determined for nickel straining electrode samples tested at cathodic potentials. This relationship can be expressed as C /SUB s/ ..cap alpha.. P /SUP -n/ /SUB H2/ where C /SUB s/ is the critical grain boundary sulfur concentration corresponding to 50 pct transgranular and 50 pct intergranular fracture and P /SUB H2/ is the hydrogen pressure. The value of n was found to be between 0.34 and 0.9. This expression was derived by relating C /SUB s/ to th hydrogen overpotential with the Nernst equation. At a cathodic test potential of -0.3 V (SCE). C /SUB s/ was equal to 0.20 monolayers of sulfur and at higher cathodic potentials or higher hydrogen pressures, C /SUB s/ decreased such that at -0.72 V (SCE) C /SUB s/ was equal to 0.045 monolayers of sulfur. The inverse hydrogen pressure dependence observed with cathodic hydrogen is similar to that for the hydrogen permeation rate or a critical hydrogen concentration derived by Gerberich et al. for gaseous hydrogen. This similarity between gaseous and cathodic hydrogen suggests that grain boundary impurities contribute to the hydrogen embrittlement process without altering the embrittlement process although this result does not indicate whether decohesion or plasticity dependent processes are responsible for the combined sulfur-hydrogen effect on the intergranular fracture of nickel.

• Research Organization: Battelle-Northwest Laboratory, Richland, WA
• OSTI ID: 6554194
• Journal Information: Metall. Trans., A; (United States), Journal Name: Metall. Trans., A; (United States) Vol. 14A:8; ISSN MTTAB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
CRYSTAL STRUCTURE
ELECTRODES
ELEMENTS
EMBRITTLEMENT
FRACTURE MECHANICS
GRAIN BOUNDARIES
HYDROGEN
HYDROGEN EMBRITTLEMENT
IMPURITIES
MECHANICAL PROPERTIES
MECHANICS
METALS
MICROSTRUCTURE
NERNST HEAT THEOREM
NICKEL
NONMETALS
PERMEABILITY
PLASTICITY
PRESSURE DEPENDENCE
QUANTITY RATIO
SULFUR CONTENT
TRANSITION ELEMENTS