Examination of fabrication process parameters for improvement of low-activation vanadium alloys

Plate products of thickness 0.25–26 mm were evaluated, for the reference V–4Cr–4Ti alloy (NIFS-HEATs), from the viewpoint of recrystallized grain structure, precipitate distribution and fracture behavior at low temperature. 6.6 mm-thick or thinner plates showed relatively homogeneous and fine grain structure, and ductile fracture behavior. For 26 mm-thick plate, however, coarsened grain structure and localized distribution of precipitate clusters suggested that further hot working should be necessary to obtain the similar properties to those of the thinner plates. Grain structure, precipitate distribution, and anisotropy of fracture mode were shown to be influenced deeply by working and heating history at breakdown processes of the ingot. From the results the optimum fabrication parameters for vanadium alloys are discussed.