Classification of titanium alloys

Classification of titanium alloys

   titanium alloys is allotrope, melting point 1720 ℃, showed a close-packed hexagonal lattice structure, called α titanium at temperatures below 882 ℃; body-centered cubic structure over 882 ℃ character was called β titanium. The use of the different characteristics of the two titanium structures, adding appropriate alloying elements, so that the phase transition temperature, and gradually change the phase content of different tissues obtained titanium alloy bar. At room temperature, there are three titanium matrix organization, titanium will be divided into the following three categories: α alloy '(α + β) alloys and β alloys. China respectively TA, TC, TB, said.
α titanium
It is a single phase alloy consisting of α-phase solid solution, either at ambient temperatures or at higher temperatures the practical application, are the α phase, organizational stability, wear resistance higher than that of pure titanium, high resistance to oxidation. At a temperature of 500 ℃ ~ 600 ℃, and maintains its strength and creep resistance, but can not be heat strengthened, not high temperature strength.
β titanium alloy
It is a single-phase alloy consisting of β-phase solid solution, that is not heat-treated after having a high strength, hardening, aging alloy has been further strengthened, the room temperature strength of up to 1372 ~ 1666 MPa; but poor thermal stability, and should not be used at high temperatures .
α + β titanium alloy
It is duplex alloys, has a good overall performance, good organizational stability, good toughness, ductility and high temperature deformation properties, can better thermal pressure processing, can be quenched, aging of the alloy strengthening. Strength after the heat treatment higher than the annealed state of about 50% to 100%; high temperature strength, long-term work at a temperature of 400 ℃ ~ 500 ℃, the thermal stability is inferior α titanium alloy.
The most commonly used three kinds of titanium alloy is α and α + β titanium alloy; α titanium alloy machinability best, α + p titanium followed, β titanium worst. α titanium codenamed TA, β titanium codenamed TB, α + β titanium codenamed TC.
   Titanium can be divided according to use heat-resistant alloys, high-strength alloys, corrosion resistant alloy (Ti - molybdenum, titanium - palladium alloys, etc.), low-temperature alloys and special features alloy (Ti - Fe hydrogen storage materials and titanium - nickel shape memory alloy), etc. . Table typical composition and performance of the alloy.
Titanium heat treatment can be obtained by adjusting the heat treatment process and the organization of different phases. Generally considered fine equiaxed has good ductility, thermal stability and fatigue strength; needle tissue has a high rupture strength, creep strength and fracture toughness; equiaxed and needle hybrid organization has good overall performance.