Titanium is a two-phase alloy, has a good overall performance

Titanium is a two-phase alloy, 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 + β titanium followed, β titanium worst. α titanium codenamed TA, βtitanium pipe 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 alloy and alloy special features. 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.

Titanium Industry Development History

Titanium Industry Development History
1791 British clergyman W. Gregor (Gregor) discovered a new metal elements in black magnetite. In 1795 the German chemist M. H. Carat Preuss (Klaproth) rutile in the study also found that the elements, and is named after the Greek god of the Titans. 1910 American scientist M. A. Hunter (Hunter) for the first time with a sodium reduction TiCI: Preparation of titanium bar. 1940 Luxembourg scientist W. J. Kroll (kroll) with magnesium reduction TiCl: prepared titanium. Since then, the magnesium reduction method (also known as the Kroll process) and sodium reduction method (also known as Hunt France) became the industrial production of titanium sponge method. In 1948 the United States out of the magnesium reduction process 2t titanium sponge, from reaching industrial scale. Subsequently, the United Kingdom, Japan, the former Soviet Union and China have also entered the industrial production, one of the major producing country of the former Soviet Union titanium, Japan and the United States.
     Titanium is a new metal, because it has a series of excellent features, aviation, aerospace, chemical, petroleum, metallurgy, light industry, power, desalination, ships and everyday appliances are widely used in industrial production, which is hailed for modern metal. titanium bolts metal production from 1948 has only half a century of history, it is accompanied by the aerospace industry and developed new industries. Its development has withstood several ups and downs, this is because titanium and aircraft industry-related reasons. Overall, however, the speed of development of titanium is very fast, it is more than any other non-ferrous metals pace of development. This can be seen from the development of the world's titanium sponge industry: titanium sponge production scale of the 1960s 60kt / a, 70 years for 1lOkt / a, 80 years of 130kt / a, to 1992 has reached 140kt / a. Actual production in 1990 reached record levels, as 105kt / a

Titanium alloy is a titanium-based alloy by adding other elements

Titanium alloy is a titanium-based alloy by adding other elements. There are two isomeric titanium crystal:
Below 882 ℃ for α hcp titanium wire, more than 882 ℃ for the body-centered cubic β titanium.
Alloying elements according to their impact on the phase transition temperature can be divided into three categories:
① stable α phase, increase the phase transition temperature of the elements of α stabilizing element, aluminum, carbon, oxygen and nitrogen. Which is the main alloying elements aluminum alloy, improve its normal and high temperature strength of the alloy, reduce the proportion of the elastic modulus increases obviously.
② stable β-phase, reducing the element of the phase transition temperature of β stabilizing element, and can be divided isomorphic and eutectoid two. The former has molybdenum, niobium, vanadium and the like; the latter are chromium, manganese, copper, iron, silicon and the like.
③ small element of the phase transition temperature is neutral elements, zirconium and tin. Oxygen, nitrogen, carbon and hydrogen are the major impurity titanium. Oxygen and nitrogen in the α phase has a greater solubility of titanium significant strengthening effect, but the plastic drop. Typically a predetermined content of oxygen and nitrogen in titanium 0.15 to 0.2% and 0.04% to 0.05% or less, respectively. The solubility of hydrogen in α phase is very small, titanium dissolved in excess hydride hydrogen will produce the alloy brittle. Titanium is usually hydrogen content control 0.015%. Hydrogen was dissolved in titanium sheet is reversible, can be removed by vacuum annealing.

Titanium is allotrope, melting point 1668 ℃, showed a close-packed hexagonal lattice structure

Titanium is allotrope, melting point 1668 ℃, showed a close-packed hexagonal lattice structure, called α titanium alloys at temperatures below 882 ℃; body-centered cubic lattice structure at above 882 ℃ 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 relative content of different tissues obtained by gradually changing the titanium (titanium alloys). 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.
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
titanium tube 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

Titanium alloys at low and ultra-low temperature

Titanium alloys at low and ultra-low temperature, retains its mechanical properties. Low temperature performance, low interstitial elements of titanium bar, as TA7, at -253 ℃ still maintain a certain plasticity. Thus, low-temperature titanium alloy is also an important structural materials.
Large chemical activity
Chemical activity of titanium is large, a strong chemical reaction with atmospheric O, N, H, CO, CO2, water vapor, ammonia and the like. Carbon content greater than 0.2%, it will form a hard TiC in the titanium alloy; at higher temperatures, and also the role of N forms TiN hard surface; at above 600 ℃, the high hardness of hardened layer is formed of titanium absorbs oxygen ; hydrogen content increased, brittle layer will form. Absorbing gas produced brittle surface to a depth of 0.1 ~ 0.15 mm, the degree of hardening of 20% to 30%. Chemical affinity of titanium is also large, easy and sticking friction surface.
Small thermal elasticity
Thermal conductivity of titanium bolts λ = 15.24W / (mK) approximately 1/4 of nickel, iron 1/5, 1/14 aluminum, while the thermal conductivity of various titanium alloys decreased by 50% than the thermal conductivity of titanium. Elastic modulus was about 1/2 of the titanium alloy for steel, so the poor rigidity, deformation, and should not be made thin-walled elongated rod member, the machined surface when cutting a large amount of spring back, the stainless steel is about 2 to 3 times, causing severe tool flank friction, adhesion, adhesive wear.

Titanium has a high strength and density and small, good mechanical

Titanium has a high strength and density and small, good mechanical properties, good toughness and corrosion resistance. In addition, poor process performance titanium distributors alloy, machining difficulties in thermal processing, and very easy to absorb carbon hydrogen nitrogen and other impurities. There are poor abrasion resistance, complex production process. Titanium industrial production was started in 1948. Require the development of the aviation industry, the titanium industry with an average annual growth rate of about 8% of the development. World titanium alloy production reached 40,000 tons, nearly 30 kinds of titanium alloys. The most widely used titanium alloy is Ti-6Al-4V (TC4), Ti-5Al-2.5Sn (TA7) and commercially pure titanium (TA1, TA2 and TA3).
Titanium is mainly used for the production of aircraft engine compressor components, followed by structure rockets, missiles and high-speed aircraft. The mid-1960s, medical titanium and its alloys have been in general industrial applications, electrodes for electrolysis industry production, power plant condensers, oil refining and desalination heater and environmental pollution control devices. Titanium and its alloys have become a corrosion resistant structural materials. In addition, for the production of hydrogen storage materials and shape memory alloys.
China began in 1956 titanium and titanium alloy study; the mid-1960s and the development of industrial production of titanium into TB2 alloy.

Titanium is a new type of metal, and the performance of the carbon-containing

Titanium is a new type of metal, and the performance of the carbon-containing titanium impurity content of nitrogen, hydrogen, oxygen and so on, the most pure titanium iodide impurity content not exceeding 0.1%, but its low strength, high ductility. 99.5% of the performance of industrial pure titanium plate as: density ρ = 4.5g / cc, a melting point of 1725 ℃, thermal conductivity λ = 15.24W / (mK), the tensile strength σb = 539MPa, elongation δ = 25%, section shrinkage ψ = 25%, the elastic modulus E = 1.078 × 105MPa, the hardness HB195.
High strength
Density of titanium alloys is generally about 4.51g / cc,
Only 60% of steel, titanium density was close to the density of ordinary steel, some high-strength titanium alloy over the strength of the many structural steel. Therefore, the ratio of titanium strength (strength / density) is much larger than other metal structural materials, see Table 7-1, the unit can be made out of high strength, rigidity and lightweight components. Aircraft engine components, skeleton, skin, so the use of titanium fasteners and landing gear.
High heat intensity
Use temperature several hundred degrees higher than aluminum, at moderate temperatures can still maintain the desired strength, long-term work at a temperature of 450 ~ 500 ℃ of these two types of titanium tubing alloys in the range of 150 ℃ ~ 500 ℃ still very high strength, and aluminum at 150 ℃ decreased significantly when compared strength. Titanium alloy operating temperature up to 500 ℃, the aluminum alloy is below 200 ℃.
Good corrosion resistance
Titanium work in humid atmosphere and seawater, which is far superior corrosion resistance of stainless steel; for pitting, etching, stress corrosion resistance is particularly strong; alkali, chloride, chlorine, organic materials, nitric acid, sulfuric acid etc. have excellent corrosion resistance. However, the corrosion resistance of titanium with a reduction of oxygen and chromium salts medium is poor.