Helium effects on microstructural evolution in tempered martensitic steels: In situ helium implanter studies in HFIR

Journal Article · Thu Apr 30 04:00:00 EDT 2009 · Journal of Nuclear Materials, 386:338-341

DOI:https://doi.org/10.1016/j.jnucmat.2008.12.134· OSTI ID:963836

Yamamoto, Takuya; Odette, George R; Miao, Pifeng; Edwards, Danny J; Kurtz, Richard J

Microstructural evolutions in tempered martensitic steels (TMS) under neutron-irradiation, at fusion relevant He/dpa ratios and dpa rates, were characterized using a novel in situ He-implanter technique. F82H-mod3 was irradiated at 500 C in HFIR to a nominal 9 dpa and 190 or 380 appm He in both in the as-tempered (AT) and 20% cold-worked (CW) conditions. In all cases, a high number density of 1-2 nm He-bubbles were observed, along with fewer but larger 10 nm void-like faceted cavities. The He-bubbles form preferentially on dislocations and various interfaces. A slightly larger number of smaller He bubbles were observed in the CW condition. The lower He/dpa ratio produced slightly smaller and fewer He-bubbles. Comparisons of these observations to the results in nano-structured ferritic alloy (NFA) MA957 provide additional evidence that TMS may be susceptible to He-embrittlement as well as void swelling at fusion relevant He concentrations, while NFA are much more resistant to these degradation phenomena.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 963836
• Report Number(s): PNNL-SA-66972; AT6020100
• Journal Information: Journal of Nuclear Materials, 386:338-341, Journal Name: Journal of Nuclear Materials, 386:338-341 Vol. 386; ISSN 0022-3115; ISSN JNUMAM
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALLOYS
BUBBLES
CAVITIES
DISLOCATIONS
HELIUM
MARTENSITIC STEELS
SWELLING