Influence of long-term thermal aging and irradiation on microstructure of austenitic stainless steel welds
Creators
- 1. Institute of Nuclear Safety System, Inc., Institute of Nuclear Technology, Mihama, Fukui (Japan)
Description
Austenitic stainless steel weld specimens embrittled by long-term temperature-accelerated thermal aging were irradiated with 6.4 MeV iron ions at 300degC to study effects of irradiation on the steels. The microstructural change was examined by an atom probe tomography observation and the hardness change was measured with an ultra-micro hardness tester. The hardening of the ferrite phase by thermal aging was found to reduce with irradiation. The spinodal decomposition of the ferrite phase into an iron-enriched α phase and a chromium-enriched α' phase and G-phase precipitation occurred after the long-term thermal aging. The modulation of the chromium density was found to reduce with irradiation. Ni/Si enriched clusters related to G phase precipitates were also observed in ferrite phases of thermal-aged and irradiated specimens. Formation of these clusters was enhanced by irradiation. The effects of Mo on the microstructure of ferrite phases were reducing spinodal decomposition and enhancing cluster formation under thermal aging and irradiation. (author)
Abstract (Japanese)
オーステナイト系ステンレス鋼溶接金属への熱時効と照射の影響を明らかにすることを目的に,長期熱時効させた316Lおよび308L溶接金属をイオン照射して硬さの変化とミクロ組織の変化を調べた.その結果,熱時効により増加したフェライト相の硬さは照射により減少することを確認するとともに,その原因は熱時効によるスピノーダル分解,すなわちCr濃度の局所的な変化が減少することであることが分かった.イオン照射のように速い損傷速度条件下では照射がスピノーダル分解への熱時効影響を加速しないことが確認された.一方,照射は熱時効により形成した溶質原子クラスタを成長させる傾向が見られたが,未時効材でも同様なクラスタ形成が認められ,クラスタ形成に対する熱時効と照射の重畳影響は小さいことが示唆された.また,Mo はスピノーダル分解を抑制する効果があるのに対して,クラスタ形成を促進する効果があることが分かった.(著者)Additional details
Additional titles
- Original title (Japanese)
- オーステナイト系ステンレス鋼溶接金属のミクロ組織への熱時効と照射の影響
Publishing Information
- Journal Title
- INSS Journal
- Journal Volume
- 25
- Journal Page Range
- p. 75-90
- ISSN
- 1340-4482
INIS
- Country of Publication
- Japan
- Country of Input or Organization
- Japan
- INIS RN
- 50004654
- Subject category
- S36: MATERIALS SCIENCE; S21: SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS;
- Descriptors DEI
- AGING; CHEMICAL COMPOSITION; DUCTILITY; FERRITE; HARDNESS; IRON IONS; IRRADIATION; MICROSTRUCTURE; PRECIPITATION; PWR TYPE REACTORS; REACTOR MATERIALS; STAINLESS STEEL-316L; TOMOGRAPHY; WELDED JOINTS
- Descriptors DEC
- ALLOYS; AUSTENITIC STEELS; CARBON ADDITIONS; CHARGED PARTICLES; CHROMIUM ALLOYS; CHROMIUM STEELS; CHROMIUM-MOLYBDENUM STEELS; CHROMIUM-NICKEL STEELS; CHROMIUM-NICKEL-MOLYBDENUM STEELS; CORROSION RESISTANT ALLOYS; DIAGNOSTIC TECHNIQUES; ENRICHED URANIUM REACTORS; HEAT RESISTANT MATERIALS; HEAT RESISTING ALLOYS; HIGH ALLOY STEELS; IONS; IRON ALLOYS; IRON BASE ALLOYS; JOINTS; LOW CARBON-HIGH ALLOY STEELS; MATERIALS; MECHANICAL PROPERTIES; MOLYBDENUM ALLOYS; NICKEL ALLOYS; POWER REACTORS; REACTORS; SEPARATION PROCESSES; STAINLESS STEELS; STEEL-CR17NI12MO3-L; STEELS; TENSILE PROPERTIES; THERMAL REACTORS; TRANSITION ELEMENT ALLOYS; WATER COOLED REACTORS; WATER MODERATED REACTORS
Optional Information
- Notes
- 18 refs., 16 figs., 2 tabs.