The role of grain boundary chemistry and structure in the environmentally-assisted intergranular cracking of nickel-base alloys. Progress report, August 1, 1993--July 31, 1994

Technical Report · Fri Jul 01 04:00:00 EDT 1994

OSTI ID:10194376

Was, G S

In the past year, progress has been made in several areas. Creep tests conducted in both primary water at controlled potentials and in inert argon show that the water environment provides an enhancement in creep rate by a factor of 5--10 over that in argon, regardless of the applied potential. Cracking is most severe in the water tests, but correlates best with the amount of creep strain, supporting a creep damage accumulation model. Creep experiments on carbon doped heats of Ni-16Cr-9Fe support earlier findings that the creep rate and the amount of IG cracking are strong functions of the amount of carbon in solution. Experiments on two heats containing the same amount of carbon in solution, but one of which contains grain boundary carbides show that carbides are ineffective in preventing Ig cracking if the amount of carbon in solution is low. Grain boundary misorientation studies confirm that thermal treatments which produce a larger proportion of CSL boundaries exhibit significantly lower creep rates (by 10x) and have a higher yield strength (by 25 MPa). In support of these studies, an electron backscattering patterns (EBSP) imaging system for use in an environmental scanning electron microscope (ESEM) has just recently been completed to provide determination of grain boundary misorientation on small grain (30 {mu}m) samples. In addition, a multiple constant load test (MCLT) system has just been completed to provide for the simultaneous and independent creep testing of up to 3 samples in high temperature water.

• Research Organization: Michigan Univ., Ann Arbor, MI (United States). Dept. of Nuclear Engineering
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: FG02-85ER45184
• OSTI ID: 10194376
• Report Number(s): DOE/ER/45184--10; ON: DE95002941; BR: KC0201020
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
210100
210200
36 MATERIALS SCIENCE
360102
360103
360105
CARBON
CHROMIUM ALLOYS
CORROSION
CORROSION AND EROSION
CRACK PROPAGATION
CREEP
DEFORMATION
EXPERIMENTAL DATA
IRON ALLOYS
MECHANICAL PROPERTIES
MECHANICAL TESTS
METALLURGICAL EFFECTS
MICROSTRUCTURE
NICKEL BASE ALLOYS
POWER REACTORS
NONBREEDING
LIGHT-WATER MODERATED
BOILING WATER COOLED
POWER REACTORS
NONBREEDING
LIGHT-WATER MODERATED
NONBOILING WATER COOLED
PRIMARY COOLANT CIRCUITS
PROGRESS REPORT
REACTOR MATERIALS
STRUCTURE AND PHASE STUDIES
WATER COOLED REACTORS