Reduced activation ferritic / martensitic steel, F-82H (Fe-8Cr-2W-V-Ta), was irradiated in the High Flux Isotope Reactor (HFIR) to doses between 11 and 34 dpa at 400 and 500°C. Post irradiation tensile tests were performed at the nominal irradiation temperature in vacuum. Some specimens included 10 B or natural boron (nB) to estimate the helium effect on tensile properties.

Tensile properties including the 0.2% offset yield stress, the ultimate tensile strength, the uniform elongation and the total elongation were measured. The tensile properties were not depend on helium content in specimens irradiated to 34 dpa; however 10 B-doped specimens with the highset levels of hilium showed slightly higher yield strength and less ductility than boron-free specimens. Strength appears to go through a peak, and ductility through a trough at about 11 dpa. The irradiation to more than 21 dpa reduced the strength and increased the elongation to the unirradiated levels.