Long term thermal aging of cast duplex stainless steels

Book · Sun Sep 01 04:00:00 EDT 1996

OSTI ID:277817

Suzuki, Isao; Koyama, Masakuni ^[1]; Kawaguchi, Seiichi ^[2]; Mimaki, Hidehito ^[3]; Akiyama, Mamoru; Mishima, Yoshitsugu ^[4]; Okubo, Tadatsune ^[5]; Mager, T R

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1. Japan Power Engineering and Inspection Corp., Tokyo (Japan)
2. Mitsubishi Heavy Industries, Ltd., Takasago (Japan)
3. Mitsubishi Heavy Industries, Ltd., Kobe (Japan)
4. Univ. of Tokyo (Japan)
5. Sophia Univ., Tokyo (Japan)

Cast duplex stainless steels of CF8M and CF8 are used in major components because of their superior characteristics, such as corrosion resistance, weldability and so on. But, these stainless steels are known to have tendency of thermal aging embrittlement after long term service. Therefore, mechanical properties and metallurgical structure were investigated using materials aged at 290--400 C up to 30,000 hours. As the results show, effects of thermal aging on mechanical properties and metallurgical behavior were identified. In addition, prediction method for Charpy absorbed energy and fracture toughness was established. The following results have been obtained: (1) it was recognized that Charpy absorbed energy and fracture toughness tend to decrease and the tensile strength tend to increase with the increasing aging time; (2) it was confirmed that thermal aging embrittlement was caused by the phase separation in ferrite from the test results of APFIM; (3) in the degradation prediction model development the prediction model was applied to the material test data, including materials aged for 30,000 hours. As the results, the degradation prediction formulas for CVRT, CVHT, J{sub IC} and J{sub 6} were obtained. The toughness of cast duplex stainless steels during service could be estimated from chemical composition using this method.

• OSTI ID: 277817
• Report Number(s): CONF-960306--; ISBN 0-7918-1226-X
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
36 MATERIALS SCIENCE
AGING
CHROMIUM-NICKEL STEELS
EMBRITTLEMENT
EXPERIMENTAL DATA
FRACTURE PROPERTIES
MECHANICAL PROPERTIES
MECHANICAL TESTS
MICROSTRUCTURE
REACTOR MATERIALS
TEMPERATURE RANGE 0400-1000 K