Development of an oxide dispersion strengthened, reduced-activation steel for fusion energy

A reduced-activation steel having a nominal chemical composition of Fe, 9% Cr, 2% W, 0.25% V, 0.1% Ta, and 0.1% C was mechanically alloyed with a fine dispersion of Y2O3 and TiO2 to assess the potential for extending the elev ated temperature limit of this ahoy for structural applications. The total oxide dispersion content was varied from 0.25% to 1% and the molar ratio, T iO2/Y2O3 from 0 to 2. An argon atomized 9Cr2WVTa steel powder was ball mill ed under vacuum, extruded at 1150 degreesC to a 16 to 1 reduction in area, followed by a normalize and age heat treatment. Mechanical properties were assessed by elevated temperature tensile tests over the temperature range f rom room temperature to 800 degreesC. Transmission electron microscopy reve aled a favorable dispersion of the oxide particles. Oxide dispersion streng thening by mechanical alloying resulted in significant improvement in eleva ted temperature tensile strengths. Extended ball-milling times improved oxi de dispersion, microstructural refinement, and mechanical properties. (C) 2 000 Elsevier Science B.V. All rights reserved.