Intergranular attack of Alloy 600

Conference · Thu Jan 01 04:00:00 EST 1987

OSTI ID:7202082

Aspden, R G; Economy, G; Kunig, R H; Connor, W M

Parametric studies of laboratory initiated intergranular attack (IGA) is mill annealed Alloy 600 were conducted. In isothermal capsule tests an increase in test temperature from 600 to 650/sup 0/F and, to a lesser extent, an increase in caustic concentration from near 10 to 50 weight percent enhanced IGA. Only one addition, Cr/sub 2/O/sub 3/, to caustic strongly increased the IGA rate. The contribution of some organic environments to IGA and stress corrosion cracking (SCC) was evaluated at 610/sup 0/F. Highly stressed C-rings exhibited IGA and SCC in sodium phenoxide and sodium formate, unstable environments, but not in the sodium acetate solution. The decomposition products of these unstable organics probably contributed to the aggressiveness of these environments. In superheated cervice experiments with crevice temperatures near 610/sup 0/F, chemical additions were made of 10 ppm of sodium carbonate or of sodium hydroxide plus potassium hydroxide. IGA rates were the highest near the bottom of the tubesheet crevice (up to 7.9 mils per year-mpy). Increasing the tubesheet temperature to 650/sup 0/F and packing the crevices with chromium chromium oxide, caused enhanced SCC and IGA. IGA rates up to 47.4 mpy were obtained. Such IGA rates are comparable to those obtained in Alloy 600 capsules at 650/sup 0/F using the most aggressive environment of caustic plus chromium oxide. Neither sulfur contamination nor hydrogen influenced the IGA rates.

• OSTI ID: 7202082
• Report Number(s): CONF-870314-
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103 -- Metals & Alloys-- Mechanical Properties
360105* -- Metals & Alloys-- Corrosion & Erosion
ACETATES
ALKALI METAL COMPOUNDS
ALLOYS
AROMATICS
CARBON COMPOUNDS
CARBONATES
CARBOXYLIC ACID SALTS
CHALCOGENIDES
CHEMICAL REACTIONS
CHROMIUM ALLOYS
CHROMIUM COMPOUNDS
CHROMIUM OXIDES
CORROSION
CORROSIVE EFFECTS
CRACKS
CREVICE CORROSION
FORMATES
FRACTURE MECHANICS
HIGH TEMPERATURE
HYDROGEN COMPOUNDS
HYDROXIDES
HYDROXY COMPOUNDS
INCONEL 600
INCONEL ALLOYS
INTERGRANULAR CORROSION
IRON ALLOYS
ISOTHERMS
MECHANICS
NICKEL ALLOYS
NICKEL BASE ALLOYS
NIOBIUM ALLOYS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHENOLS
POTASSIUM COMPOUNDS
POTASSIUM HYDROXIDES
SODIUM CARBONATES
SODIUM COMPOUNDS
SODIUM HYDROXIDES
SODIUM OXIDES
STRESS ANALYSIS
STRESS CORROSION
THERMAL ANALYSIS
TRANSITION ELEMENT COMPOUNDS