Development of ferritic steels for fusion reactor applications
Chromium-molybdenum ferritic (martensitic) steels are leading candidates for the structural components for future fusion reactors. However, irradiation of such steels in a fusion environment will produce long-lived radioactive isotopes that will lead to difficult waste-disposal problems. Such problems could be reduced by replacing the elements in the steels (i.e., Mo, Nb, Ni, N, and Cu) that lead to long-lived radioactive isotopes. We have proposed the development of ferritic steels analogous to conventional Cr-Mo steels, which contain molybdenum and niobium. It is proposed that molybdenum be replaced by tungsten and niobium be replaced by tantalum. Eight experimental steels were produced. Chromium concentrations of 2.25, 5, 9, and 12% were used (all concentrations are in wt %). Steels with these chromium compositions, each containing 2% W and 0.25% V, were produced. To determine the effect of tungsten and vanadium, 2.25 Cr steels were produced with 2% W and no vanadium and with 0.25% V and O and 1% W. A 9Cr steel containing 2% W, 0.25 V, and 0.07% Ta was also studied. For all alloys, carbon was maintained at 0.1%. Tempering studies on the normalized steels indicated that the tempering behavior of the new Cr-W steels was similar to that of the analogous Cr-Mo steels. Microscopy studies indicated that 2% tungsten was required in the 2.25 Cr steels to produce 100% bainite in 15.9-mm-thick plate during normalization. The 5Cr and 9Cr steels were 100% martensite, but the 12 Cr steel contained about 75% martensite with the balance delta-ferrite. 33 refs., 35 figs., 5 tabs.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 6792269
- Report Number(s):
- ORNL-6472; ON: DE89001141
- Country of Publication:
- United States
- Language:
- English
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ALLOYS
CARBON ADDITIONS
CRYSTAL STRUCTURE
ELECTRON MICROSCOPY
FERRITIC STEELS
HARDNESS
IMPACT STRENGTH
IRON ALLOYS
IRON BASE ALLOYS
MARTENSITE
MATERIALS
MATERIALS TESTING
MECHANICAL PROPERTIES
MICROSCOPY
MICROSTRUCTURE
MODIFICATIONS
STEELS
STRESS ANALYSIS
TEMPERATURE DEPENDENCE
TENSILE PROPERTIES
TESTING
THERMONUCLEAR REACTOR MATERIALS
TRANSMISSION ELECTRON MICROSCOPY