Analysis of brittle intergranular crack propagation during stress corrosion cracking

Conference · Mon Apr 01 04:00:00 EST 1991

OSTI ID:5750186

Jones, R H

Crack growth rates during intergranular stress corrosion, in materials such as Fe in Ca(NO{sub 3}){sub 2} at +750 mV (SEC), appear to exceed rates which can occur by dissolution and ion transport within the crack. Brittle crack jumps induced by a corrosion or stress corrosion process, and which magnify the dissolution supported crack velocity by a factor of up to 10{sup 3}, could explain this behavior. Hydrogen can induce these very fast crack growth rates, but these rates have been obtained at electrochemical potentials where H reduction is not thermodynamically possible. Other possible mechanisms for this accelerated crack growth include: (1) intergranular corrosion altered tearing modulus, (2) grain boundary dealloying, or (3) adsorption induced brittle fracture. Examination of each of these mechanisms suggests that intergranular corrosion could reduce the tearing modulus through changes in the crack shape. However, crack opening analysis clearly shows that the crack tip is shielded from the applied stress intensity and that an embrittlement process which reduces the interface toughness is need for brittle intergranular crack jumps to occur. Further research is in progress to identify the source of this embrittlement. 17 refs., 6 figs.

• Research Organization: Pacific Northwest Lab., Richland, WA (USA)
• Sponsoring Organization: DOE; USDOE, Washington, DC (USA)
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 5750186
• Report Number(s): PNL-SA-18938; CONF-910406--21; ON: DE91013666
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
ALKALINE EARTH METAL COMPOUNDS
ALLOYS
BRITTLENESS
CALCIUM COMPOUNDS
CALCIUM NITRATES
CHEMICAL REACTIONS
CORROSION
CRACK PROPAGATION
CRACKS
CRYSTAL STRUCTURE
ELEMENTS
GRAIN BOUNDARIES
IRON
IRON ALLOYS
MECHANICAL PROPERTIES
MEETINGS
METALS
MICROSTRUCTURE
NITRATES
NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
STRESS ANALYSIS
STRESS CORROSION
TRANSITION ELEMENTS