FORMATION OF SUBMICROCRYSTALLINE STRUCTURE IN LARGE SIZE BILLETS AND SHEETS OUT OF TITANIUM ALLOYS

摘要

The structure evolution and mechanical behavior of titanium and Ti-64 alloy during successive compression of sample along three orthogonal directions or "abc" deformation were studied. It is shown formation of submicrocrystalline structure in the both materials under warm "abc" deformation. In titanium the structure evolution occurs via formation of deformation induced high angle boundaries and interaction between them that leads to formation of submicron-grained structure and strengthening. In two-phase lamellar alloy plates of phases divide into fragments, which afterwards are spheroidizied due to formation of high angle grain boundaries and transformation of semicoherent interphase boundaries to noncoherent ones. In this case superplastic flow and softening is observed. Large-scale billets and sheets with homogeneous submicrocrystalline structure were produced by "abc" deformation. Advantages of their mechanical properties were showed.