Thermomechanical Treatment of Titanium Alloys with a β-Structure

Polymorphic transformation: The basis of thermocycling treatment of titanium alloys

“…The internal factors include the difference in the specific volumes of the phases, the anisotropy of the coefficients of linear expansion, the difference in the diffusivities of the alloying elements and the admixtures, the anisotropy of the moduli of elasticity and other properties of the phases, the surface energy of the phases, the amount of vacancies, dislocations and other defects of the atomic and crystal structure, and the original state of the alloys (deformed, cast, annealed, etc. ).It has been shown in [11,12] that the rates of heating and cooling in TCT of titanium alloys can be low in contrast to steels. For example, the reduction of the heating rate of alloy Ti -6% A1 -4% V from 3.3 to 0.3 K/sec in [12] and that of alloys Vt3-1 and VT6 from 2.2 to 0.7 K/sec in [11] has improved the mechanical properties of the alloys quite considerably.…”

“…For example, the reduction of the heating rate of alloy Ti -6% A1 -4% V from 3.3 to 0.3 K/sec in [12] and that of alloys Vt3-1 and VT6 from 2.2 to 0.7 K/sec in [11] has improved the mechanical properties of the alloys quite considerably. The heating rate affects the temperature of the transformation and the grain size of titanium alloys in heating, and the cooling rate affects the mechanism of the phase transformation, the composition and sizes of phase segregations, and the structural transformations.…”

“…Analyzing the results of [6][7][8] and the data of [9][10][11] we singled out the external and internal factors that determine the state and properties of titanium alloys after thermocycling.…”