Caustic stress-corrosion behavior of Fe--Ni--Cr nuclear steam generator tubing alloys

Journal Article · Fri Oct 01 04:00:00 EDT 1976 · Nucl. Technol.; (United States)

OSTI ID:7334866

Wilson, I L.W.; Pement, F W; Aspden, R G; Begley, R T

Stress-corrosion behavior of Type 304 stainless steel, Incoloy 800, Inconel 600, and Inconel 690 has been measured in both 10 and 50 percent NaOH environments. Both U-bend and C-ring samples were utilized, and test temperatures were in the range of 600 to 630/sup 0/F. Differences in behavior between the two specimen configurations are attributed primarily to differences in stress level and distribution between the two types of specimens. Stress dependency of cracking of Inconel 600 and Incoloy 800 obtained on pressurized tubing samples was also measured. The total data indicate marked superiority of Inconel 600 at high stresses and high caustic concentrations. The C-ring samples of commercially prepared tubing were also exposed at 110 percent of the room temperature yield strength to strong (50 percent) mixtures of potassium and sodium hydroxides with and without admixtures of typical sludge species for prolonged periods. The general resistance to caustic cracking increased with the nickel content of the alloy; Type 304 stainless steel was the least resistant in all cases. Inconel Alloy 600 and the high-chromium-modification Inconel Alloy 690 were superior, with Incoloy 800 showing intermediate behavior. In uncontaminated caustic, only the stainless steels and Incoloy cracked in a three-month exposure, and a six-month exposure was required to produce attack in the Inconel 600. The additions of silica or silica-containing mixtures promoted attack. Low-level additions of halides or lead oxide did not enhance the caustic cracking.

• Research Organization: Westinghouse Research Labs., Pittsburgh
• OSTI ID: 7334866
• Journal Information: Nucl. Technol.; (United States), Journal Name: Nucl. Technol.; (United States) Vol. 31:1; ISSN NUTYB
• Country of Publication: United States
• Language: English

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ALKALI METAL COMPOUNDS
ALLOYS
AQUEOUS SOLUTIONS
BOILERS
CHEMICAL REACTIONS
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-NICKEL STEELS
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CRACKS
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HIGH TEMPERATURE
HYDROGEN COMPOUNDS
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INCOLOY 800
INCOLOY ALLOYS
INCONEL 600
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IRON ALLOYS
IRON BASE ALLOYS
MIXTURES
NICKEL ALLOYS
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NIOBIUM ALLOYS
OXYGEN COMPOUNDS
POTASSIUM COMPOUNDS
POTASSIUM HYDROXIDES
PWR TYPE REACTORS
REACTORS
SODIUM COMPOUNDS
SODIUM HYDROXIDES
SOLUTIONS
STAINLESS STEEL-304
STAINLESS STEELS
STEAM GENERATORS
STEELS
STRESS CORROSION
VAPOR GENERATORS
WATER COOLED REACTORS
WATER MODERATED REACTORS