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Hardness and microstructural response to thermal annealing of irradiated ASTM A533B class 1 plate steel

Conference ·
OSTI ID:679496
 [1];  [2]; ;  [3];  [4]
  1. SMS Concast, Inc., Pittsburgh, PA (United States)
  2. Univ. of Missouri, Rolla, MO (United States)
  3. Pacific Northwest Lab., Richland, WA (United States)
  4. Electric Power Research Inst., Charlotte, NC (United States)
Hardness measurements were used to determine the post-irradiation annealing response of A533B class 1 plate steel irradiated to a fluence of 1 {times} 10{sup 19} n/cm{sup 2} (E > 1 MeV) at 150 C. Rockwell hardness measurements indicated that the material had hardened by 6.6 points on the B scale after irradiation. The irradiation induced hardness increase was associated with a decrease in upper shelf energy from 63.4 J to 5-1.8 J and a temperature shift in the Charpy curve at the 41 J level from 115 C to 215 C. Specimens were annealed after irradiation at temperatures of 343 C (650 F), 399 C (750 F), and 454 C (850 F) for durations of up to one week (168 h). Hardness measurements were made to chart recovery of hardness as a function of time and temperature. Specimens annealed at the highest temperature 454 C recovered the fastest, fully recovering within 144 h. Specimens annealed at 399 C recovered completely within 168 h. Specimens annealed at the lowest temperature, 343 C recovered only {approximately}70% after 168 h of annealing. After neutron irradiation, a new feature of black spot damage was found to be superimposed on the unirradiated microstructure. The density of black spots was found to vary from 2.3 {times} 10{sup 15}/cm{sup 3} to 1.1 {times} 10{sup 16}/cm{sup 3} with an average diameter of 2.85 nm. Following annealing at 454 C for 24 h the black spot damage was completely annealed out. It was concluded that the black spot damage was responsible for 70% of the irradiation-induced hardness.
Research Organization:
Sandia National Laboratory
DOE Contract Number:
AC04-76DP00789; AC04-94AL85000
OSTI ID:
679496
Report Number(s):
CONF-960643--
Country of Publication:
United States
Language:
English