RECRYSTALLIZATION OF BETA-HEAT-TREATED DINGOT-URANIUM CORES. Topical Report
Annealing beta-heat-treated production-size dingoturanium core blanks in the high alpha range (1150 to 1200 deg F) produced a fine, equiaxed grain size by a recrystallization process. The extent of recrystallization is dependent upon the rate of cooling through the beta-to-alpha transformation, the time and temperature of annealing, and whether or not impurities that retard grain growth are present. The cooling rate through the beta-to-alpha transformation was varied by using a range of beta temperatures and air cooling times prior to quenching into water. Longer air cooling times are permissible at the higher beta temperatures; however, the greatest amount of induced lattice strain was obtained after an air delay of only 2 seconds before quenching. Decreasing the annealing temperature results in a corresponding increase in the annealing time required for an equivalent amount of recrystallization. A second phase, present in the alloyed dingot metal, inhibited recrystallization and grain growth. Alloyed metal recrystallized progressively from the outer periphery to the center of the core, whereas unalloyed metal subjected to identical annealing conditions exhibited recrystallized grains throughout the cross section. A reduction in grain size from 0.38 mm to 0.25 mm occurred in a beta-treated, unalloyed core after annealing at 1200 deg F for 4 hours. The grain size of betaquenched, alloyed metal decreased from 0.28 mm to 0.19 mm on recrystallization. There appears to be change in the orientation of a beta-quenched core as a result of recrystallization. The beta quench-alpha anneal process could be integrated with an alpha-phase vacuum outgassing process to produce fine-grained metal that is essentially free of strain and preferred orientation and has a low hydrogen c ontent. (auth)
- Research Organization:
- Mallinckrodt Chemical Works, Uranium Div., Weldon Spring, Mo.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-14-108-ENG-8
- NSA Number:
- NSA-16-029373
- OSTI ID:
- 4792031
- Report Number(s):
- MCW-1460
- Resource Relation:
- Other Information: Orig. Receipt Date: 31-DEC-62
- Country of Publication:
- United States
- Language:
- English
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