Effect of oxidation on crack extension rate of fine-grained isotropic graphite
- 1. Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment
Description
The effect of oxidation on tensile strength, fracture toughness and crack extension rate was examined for an isotropic fine-grained graphite IG-11, a candidate material for the graphite components of an HTGR. Oxidation tests were performed at 500℃ in air. Drastic decreases in tensile strength and fracture toughness values after oxidation were observed. The ratio of their values after oxidation to those before oxidation decreased with increasing the ratio of the apparent density after oxidation to that before oxidation. The crack extension rate da/dN was well expressed as da/dN = 0.454(ΔK - ΔKth)4.0, where the value ΔKth decreased as oxidation proceeds. As a result, the crack extension rate increased with increase of burnoff level. The result was considered to be due to the formation of pores less than 1 μm and that of larger pores which were observed on the fracture surface of oxidized specimens. (author)
Availability note (English)
Available from DOI: https://doi.org/10.3327/jaesj.28.966Abstract (Japanese)
高温ガス炉炉心黒鉛構造物用候補材料としての微粒等方性黒鉛IG-11の引張り強さ、破壊靭性値及びき裂進展速度に及ぼす酸化の影響を調べた。酸化は500℃の空気中で行った。酸化後の引張り強さと破壊靭性値は酸化前に比べて大きく減少した。すなわち、酸化前後のそれらの値の比は酸化前後の密度の比の増加と共に低下した。DCB試験片を用いて測定したき裂進展速度(da/dN)は応力拡大計数範囲の差(ΔK-ΔKth)に対して、da/dN=(ΔK-ΔKth)4.0のように表される。ここで、ΔKthは酸化の進行に伴い減少した。その結果、き裂進展速度は酸化重量減と共に増加した。この結果は、1μm以下の気孔の生成と酸化試料の破面に観察される大きい気孔の生成によるものと考察された。(著者)Additional details
Additional titles
- Original title (Japanese)
- 微粒等方性黒鉛の亀裂進展速度に及ぼす酸化の影響
Identifiers
- DOI
- 10.3327/jaesj.28.966;
Publishing Information
- Journal Title
- Nippon Genshiryoku Gakkai-Shi
- Journal Volume
- 28
- Journal Issue
- 10
- Journal Page Range
- p. 966-971
- ISSN
- 0004-7120
- CODEN
- NGEGAL
INIS
- Country of Publication
- Japan
- Country of Input or Organization
- Japan
- INIS RN
- 54003929
- Subject category
- S36: MATERIALS SCIENCE;
- Descriptors DEI
- CRACK PROPAGATION; FRACTURE PROPERTIES; GRAPHITE; HTGR TYPE REACTORS; JAERI; MECHANICAL TESTS; OXIDATION; POROSITY; TEMPERATURE RANGE 0400-1000 K; TENSILE PROPERTIES; YOUNG MODULUS
- Descriptors DEC
- CARBON; CHEMICAL REACTIONS; ELEMENTS; GAS COOLED REACTORS; GRAPHITE MODERATED REACTORS; JAPANESE ORGANIZATIONS; MATERIALS TESTING; MECHANICAL PROPERTIES; MINERALS; NATIONAL ORGANIZATIONS; NONMETALS; REACTORS; TEMPERATURE RANGE; TESTING
Optional Information
- Notes
- This record replaces 18076000