METHOD OF TREATMENT OF TITANIUM ALLOYS Russian patent published in 1999 - IPC

FIELD: treatment of titanium alloys. SUBSTANCE: method includes heating of billet and its deformation in heated tools at 400 C - Tpt, where Tpt is temperature of full polymorphic transformation. In so doing, quantity of stages and their temperatures are set proceeding from grain sizes d_o of initial billet and required grain final size d_f and temperature Tf corresponding to required grain final size. The process is carried out as follows. Determined experimentally is dependence of size of recrystallized grains on temperature d = f(T) in the entire indicated temperature range. The latter is divided into two sections and boundary between them is determined by temperature T^* corresponding to grain size and the latter is determined from relation lg d_o/d^*=2.4-2.6 for alloys with stabilization factor Kβ < 1.4, and lg d_o/d^*=1.8-2 for alloys with stabilization factor Kβ ≥ 1.4. If deformation temperature Tf is within range of ( T^* - Tpt), deformation is effected for one stage, and if deformation temperature is within (400 C - T^*), deformation is effected for several stages. In the latter case, quantity and temperature of stages are determined by successive adding to temperature Tf of temperature difference between stages determined by curve d = f(T) as value ensuring reduction of grain sizes at stages by 2-10 times until deformation temperature exceeds or becomes equal to T^*. In this case deformation at stage is effected with reduction ratio e amounting to not less than 0.6, and heating at the next stage is carried out to temperature not exceeding deformation temperature of the preceding stage. EFFECT: higher efficiency. 42 cl, 12 dwg