Method of Manufacturing Semi-Finished Sheet Products From Titanium Alloy

The invention relates to plastic working of metals, more specifically to rolling sheets, and is concerned with a method of manufacturing a semi-finished sheet product from a titanium alloy having a submicrocrystalline structure suitable for low-temperature superplastic deformation. The invention can be most efficiently used to manufacture semi-finished thin sheets, including foil, from a low-plastic two-phase titanium alloy. The object of the invention is to improve quality of semi-finished sheet products made from a titanium alloy adapted for further low-temperature superplastic deformation. A method of manufacturing a semi-finished sheet product from a titanium alloy adapted for low-temperature superplastic deformation, including rolling a billet with a prepared structure at a temperature below the polymorphous transformation temperature in isothermal or quasi-isothermal conditions provided by heating the rolls, the method characterized in that said rolling is carried out in conditions of low-temperature superplastic deformation, the deformation being performed, predominantly in a first pass, to a strain amount of epsilon>=epsilonmin, where epsilonmin is the minimum amount at which a structural state required to provide cooperative grain boundary sliding in the deformation process is formed in the alloy in selected rolling temperature/rate conditions; after each subsequent rolling pass the billet is cooled immediately on exiting the deformation region to maintain the structural state obtained in the deformation; a time period of heating the billet in a furnace for a subsequent rolling pass is restricted to prevent disturbance of the alloy structural state obtained in the previous rolling pass.