Conversion of a 11 MN Extrusion Press for Hydrostatic Extrusion of Superconducting Materials

Abstract

The purpose of this program was to demonstrate the feasibility of modifying an existing mid-size conventional extrusion press to permit, with a simple tooling change, hydrostatic extrusion of superconducting materials. Hydrostatic extrusion is considered by many the ideal method for low-temperature processing of superconductors in order to (a) maximize current densities and (b) successfully coextrude widely dissimilar materials that are typically within multifilament superconductor billets. Successful conversion of a midsize press could then ultimately lead to a similar modification of a much larger existing production extrusion press. This would provide the U.S. with a production capability at a much lower cost than would otherwise be possible. Battelle Columbus Division (BCD), as a sub-contractor to Supercon Inc., undertook the task of converting a 11 MN press located at Battelle’s Pacific Northwest Division (BPND). The converted press was designed to accommodate billets up to 94 mm in diameter x 559 mm long. Also, the converted tooling was designed to operate at extrusion pressures up to 1517 MPa. Feasibility of the converted press was demonstrated by successfully extruding Cu/NbTi, AI/NbTi, and Cu/Nb/Sn billets under conditions comparable to those used for hydrostatic extrusion of the same materials in a 39.1 MN production hydrostatic extrusion press. In addition, enhanced critical current densities in Cu/NbTi composites are shown for hydrostatically extruded materials.