Correlation between oxidation and stress corrosion cracking of U--4. 5 wt % Nb

Conference · Sun Jan 01 04:00:00 EST 1978 · Corrosion; (United States)

OSTI ID:6447136

Magnani, N J; Holloway, P H

To investigate the mechanisms causing stress corrosion cracking (SCC) on uranium alloys, the kinetics of crack propagation and oxide film growth for U--4.5% Nb have been investigated at temperatures between 0 and 200 C in oxygen, water vapor, and oxygen--water vapor mixtures. Three regions of crack velocity vs stress intensity were observed in laboratory air. At low stress intensities (but above an effective K/sub ISCC/ of 22 MN/m/sup 3/2/) crack velocity varied approximately as K/sup 70/. In an intermediate stress intensity region (region II), the crack velocity was dependent upon K/sup 4/. In the high stress intensity region, mechanical overloading was observed and crack velocities varied approximately as K/sup 12/. Both cracking (region II) and oxidation rates were characterized by an activation energy of 7 Kcal/mole. For SCC, it was shown that oxygen was the primary stress corrodent, but a synergistic effect upon crack propagation rates was observed for oxygen--water vapor mixtures. Crack velocities were dependent upon the pressure of oxygen (P/sub O/sub 2///sup 1/3/) and water vapor, while the oxidation rate was essentially independent of the pressure of these species. Stress sorption and oxide film formation SCC mechanisms were considered and reconciled with the stress corrosion and oxidation data.

• Research Organization: Sandia Labs., Albuquerque, NM
• OSTI ID: 6447136
• Conference Information: Journal Name: Corrosion; (United States) Journal Volume: 34:1
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360105* -- Metals & Alloys-- Corrosion & Erosion
ACTINIDE ALLOYS
ACTIVATION ENERGY
ALLOYS
CHEMICAL REACTIONS
CORROSION
CORROSIVE EFFECTS
CRACKS
CRYOGENIC FLUIDS
ELEMENTS
ENERGY
FLUIDS
HYDROGEN
HYDROGEN COMPOUNDS
NIOBIUM ALLOYS
NONMETALS
OXIDATION
OXYGEN
OXYGEN COMPOUNDS
PRESSURE DEPENDENCE
STRESS CORROSION
SURFACES
TEMPERATURE DEPENDENCE
URANIUM ALLOYS
URANIUM BASE ALLOYS
WATER