Temperature dependence of nitrate stress corrosion cracking of mild steel

Conference · Sat Jan 01 04:00:00 EST 1977

OSTI ID:5244251

Donovan, J. A.

The temperature dependence of nitrate stress corrosion in mild steel is given by activation energies of 27 kJ/mol for continuous and 56 kJ/mol for discontinuous crack growth. The mechanism of nitrate stress corrosion in mild steel has been interpreted as anodic dissolution, and these results support this interpretation, except that an intergranular oxide is formed and the metal is not dissolved directly. If the stress intensity, K, increases, then the mode of crack growth is fracture of the intergranular oxide or the oxide-metal interface. Nevertheless, anodic dissolution is an inherent part of the process, but by the solid state reaction in the grain boundaries. An initiation time is required even in precracked specimens, and this observation is attributed to the time required to form intergranular oxide. The suggested controlling mechanisms are dissolution of the intergranular oxide in specimens in which k decreases with crack length and grain-boundary diffusion of oxygen in specimens in which K increases.

• Research Organization: Du Pont de Nemours (E.I.) and Co., Aiken, S.C. (USA). Savannah River Lab.
• DOE Contract Number: EY-76-C-09-0001
• OSTI ID: 5244251
• Report Number(s): DP-MS-77-25; CONF-771066-1
• 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
CRACKS
FRACTURE PROPERTIES
INTERGRANULAR CORROSION
IRON ALLOYS
IRON BASE ALLOYS
MECHANICAL PROPERTIES
STEELS
STRESS CORROSION
TEMPERATURE DEPENDENCE