α,β,α+β Titanium
Titanium is isomer, based on titanium alloy with other alloying elements is called titanium alloy, melting point is 1668℃, below 882℃ shows a dense hexagonal lattice structure, known as α titanium; At 882℃ above the body - centered cubic lattice structure, called β titanium. By making use of the different characteristics of the two structures of titanium, appropriate alloying elements are added to make the phase transition temperature and phase fraction content of the alloys change gradually to obtain titanium alloys of different structures. At room temperature, titanium alloys have three matrix structures, which can be divided into three categories: α alloy,(α+β) alloy, and β alloy. China is represented by TA, TC and TB.
1, α titanium alloy
It is a single-phase alloy composed of α-phase solid solution, whether at the general temperature or at a higher practical application temperature, is α-phase, stable structure, wear resistance is higher than pure titanium, strong oxidation resistance. At the temperature of 500℃ ~ 600℃, it still maintains its strength and creep resistance, but it can not be strengthened by heat treatment, and the strength is not high at room temperature.
2, β titanium alloy
It is a single phase alloy composed of β phase solid solution, which has high strength without heat treatment. After quenching and aging, the alloy is further strengthened, and the strength at room temperature can reach 1372 ~ 1666 MPa. But the thermal stability is poor, should not be used at high temperature.
3, α+β titanium alloy
It is a two-phase alloy, has good comprehensive performance, good structure stability, good toughness, plasticity and high temperature deformation properties, can be better hot pressure processing, can be quenched, aging to strengthen the alloy. The strength after heat treatment is about 50% ~ 100% higher than that in annealing state. High temperature strength, can work at 400℃ ~ 500℃ for a long time, its thermal stability is inferior to α titanium alloy.
The most commonly used titanium alloys are α-titanium alloy and α-+ β-titanium alloy; The machinability of α titanium alloy is the best, followed by α+β titanium alloy and then β titanium alloy. The alpha titanium alloy was code-named TA, the beta titanium alloy was code-named TB, and the α+ beta titanium alloy was code-named TC.
