Cold Working of Titanium and Ti6A14V Alloy by Hydrostatic Extrusion

Abstract

Many technical problems concerning the mechanical installation and lubricants for hydrostatic extrusion have been solved [1,2]. In investigations of the influence of deformation on the microstructure under biaxial stress at 20°C [3] and of the partial hydrostatic extrusion [4] of titanium alloys, hexagonal dislocation networks were observed in the deformation zone of a biaxial deformed Ti5Al2.5Sn alloy and in the unextruded part of a billet of titanium which contained 0.35 wt.% oxygen. The networks which occurred exclusively on the basal planes were explained as being caused by the biaxial stress state which originated from the strain of the imposed hydrostatic pressure and/or by the deformation fields extended back into the billet due to the die geometry. With Ti6A14V it was shown that hydrostatic pressure has a favorable effect on the cold deformability and allows a higher degree of cold working as well as a more homogeneous deformation through the total area of the extruded material, compared with a material which was cold swaged [5].