Substructure and Mechanical Properties of Refractory Metal Wires

摘要

Polycrystalline columbium wires of three levels of interstitial impurity content show steady work hardening in wire drawing to the highest strain obtained, a true strain of 5.1. This behavior contrasts to f.c.c. metals, which show saturation of work hardening at true strains greater than 2. During drawing of random-texture columbium, a fibrous microstructure and the (110) wire texture continually develop. If the material has an initial (110) texture, however, the texture diminishes because of deformation band formation, and subsequent recrystallization produces near-random orientation. Swaged wire also show continued work hardening and develops a cylindrical texture at high strains. Torsion stress-strain curves for both polycrystalline and single crystal columbium have been obtained and the effect of strain reversal studied. A region of work softening was observed in both as-drawn wire and single crystals after reversal of comparable forward strains in drawn wire annealed at 700C or above prior testing. The substructures produced during these experiments were studied by electron microscopy. (Author)