Development of low-chromium, chromium-tungsten steels for fusion
- Oak Ridge National Lab., TN (United States)
High-chromium (9-12% Cr) Cr-Mo and Cr-W ferritic steels are favored as candidates for fusion applications. In the early work to develop reduced-activation steels, an Fe-2.25Cr-2W-0.25V-0.1C steel (designated 2 1/4Cr-2WV) had better strength than an Fe-9Cr-2W-0.25V-0.07Ta-0.1C (9Cr-2WVTa) steel (compositions are in weight percent). However, the 2 1/4Cr-2WV had less-than-adequate impact toughness, as determined by the ductile-brittle transition temperature and upper-shelf energy of a Charpy impact test. Because low-chromium steels have some advantages over high-chromium steels, a program to develop low-chromium steels is in progress. Microstructural analysis indicated that the reason for the inferior impact toughness of the 2 1/4Cr-2WV was the granular-bainite microstructure obtained when the steel was normalized. Properties can be improved by developing an acicular bainite structure by increasing the cooling rate after austenitization. Alternatively, acicular bainite can be promoted by increasing the hardenability. Hardenability was changed by adding small amounts of boron and chromium to the 2 1/4Cr-2WV composition. A combination of B, Cr, and Ta additions resulted in low-chromium reduced-activation steels with mechanical properties comparable to those of 9Cr-2WVTa.
- Research Organization:
- Oak Ridge National Lab., TN (United States)
- OSTI ID:
- 47738
- Report Number(s):
- DOE/ER--0313/16; ON: DE95003404
- Country of Publication:
- United States
- Language:
- English
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