Production of Sheet Half-Finished Products out of Titanium with Submicrocrystalline Structure and their Mechanical Properties

摘要

Processing to manufacture sheet half-finished products with Submicrocrystalline (SMC) structure out of the commercial titanium preforms produced by warm multiple isothermal forging was studied. It is shown that microstructure in performs is a mixed type. Submicron-sized grains and subgrains (0.1 μm), coarse grains (up to 1-2 μm), banded structure are observed. The texture in preforms is weak prominent. They have decreased density and higher strength than that in coarse-grained titanium and lower ductility. For cold rolling of ribbons and foils to prevent fracture, the preforms should be annealed at temperatures of recovery, which restrict grain growth. Ribbons, 0.8 mm in thick, and foils, 0.1 mm in thick, were produced from SMC titanium by rolling and their microstructure and mechanical properties were studied. During rolling the microstructure of ribbons and foils undergoes additional refinement, it becomes homogeneous and a basal type texture is formed. The type of texture does not depend on titanium grain size but in SMC titanium the formation of basal components of texture occurs at less strain. Ribbons and foils from titanium possess excellent mechanical properties, which are not below those of some two-phase titanium alloys.