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Nb used in Nb3Sn multifilamentary superconductor wire deforms throughout the fabrication process including the initial extrusion and subsequent drawing, restacking, re-extrusion, and final drawing steps. Unfortunately niobium, usually begins as a 300 mm diameter ingot with extremely large grains. While this ingot gets reduced to a 120-150 mm diameter bar before wire fabrication, the cast macrostructure persists. The result during wire fabrication is often non-uniform Nb – Cu co-deformation, the development non-circular Nb filaments, and the tendency for the filaments to sausage and fracture when the diameter gets small (5-10 microns). To improve conductor performance and meet the needs of advanced magnet applications, larger starting Nb bars and smaller diameter Nb filaments in Nb3Sn strands are needed. This can be accomplished by using highly grain-refined and homogeneous large cross section bars of Nb processed by severe plastic deformation. Microscopy including texture characterizations, and mechanical property measurements are reported on the grain refinement of a 175 mm diameter bar of Grade 1 Nb, to be used to fabricate a prototype multifilamentary Nb3Sn wire. This work presents success with scale-up of a new severe plastic deformation process as applied to starting Nb bar in the Nb3Sn wire fabrication process