Titanium is a new type of metal , and the performance of the titanium is based on percentage of content for carbon, nitrogen, hydrogen , oxygen and others. The pure titanium is included with iodide not more than 0.1% , but its strength is low and High plasticity. 99.5% pure titanium properties: density ρ = 4.5g/cm3, melting point 1725 ℃, thermal conductivity λ = 15.24W / (mK), tensile strength σb = 539MPa, elongation δ = 25%, reduction of area ψ = 25%, the elastic modulus E = 1.078 × 105MPa, the hardness HB195.

Specific strength：

• The density of titanium is generally about 4.5g/cm3 , only 60% of steel. Titanium is close to the intensity of ordinary steel. Some high strength super alloy is not as same strength as high strength titanium alloy steel. Therefore, specific strength titanium alloy (strength/density) is much higher than other metallic structural materials, see Table 7-1, the unit can be made of high strength and lightweight parts and components. Currently aircraft engine components, skeleton and skin are all used titanium alloy steel.

High thermal strength：

• The available temperature range is several hundred degrees higher than aluminum. It can keep the strength in middle temperature range. It can still maintain the required strength in temperature of 450 ~ 500 ℃. These two types titanium alloy steels at 150 ℃ ~ 500 ℃ range is still very high specific strength, but aluminum is with lower strength at 150 ℃ significantly. The operating temperature of titanium is up to 500 ℃, but aluminum alloys is below 200 ℃.

Good corrosion resistance：

• Titanium in the humid atmosphere and seawater still works, which is far superior corrosion resistance of stainless steel. It is also with stronger corrosion resistance against pitting, etching , stress particularly. It has good ability of corrosion resistance to alkali , chloride , chlorine, organic materials , nitric acid and sulfuric acid. However, it has poor corrosion resistance for oxide and chromium salts medium.

Good in low temperature performance：

• Titanium alloys at low and ultra- low temperatures can still maintain its mechanical properties. It can maintain certain plasticity in low temperature, such as TA7, can keep the plasticity at -253 ℃ or under. Therefore, titanium is also an important temperature structural material.

Well chemical activity：

• Titanium is with well chemical activity, having strong chemical reaction with atmospheric O, N, H, CO, CO2, water vapor , ammonia, etc. When the carbon content is over 2%, it would be formed in hard TiC. If temperature is high, it would be reacted with N to be TiN as hard surface. When it is above 600 ℃, the titanium absorbs oxygen to form as high hardness layer. If the hydrogen content increases, it would form a brittle layer. The depth of skin is up to 0.1 ~ 0.15mm and hardening degree of 20% to 30% when absorbing gas. The chemical affinity of titanium is large and easy to sticking with rubbed surface.

Poor thermal conductivity and the elastic modulus：

• The thermal conductivity of titanium is λ = 15.24W / (mK) about 1/4 of nickel, 1/5 of metal, and 1/14 of alum. The thermal conductivity for variety of titanium alloys is about 50% lower than original titanium. The elastic modulus of titanium is about 1/2 of steel, so the rigidity is poor and easy to transform. It is not suitable to produce slender rod and thin-walled machining. It has large amount of springback when cutting process. It is about 2 to 3 times than stainless steel to cause serious corrosion, stick and wear-out of blade equipment.

Uses：

• Titanium has a high strength, and density is small with good mechanical properties, toughness and good corrosion resistance. In addition, the processing performance of titanium is poor to have difficulties in cutting processing. In the thermal processing, it is easy to absorb carbon hydrogen nitrogen and other impurities. The abrasion resistance is poor and complicated in production process. 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, then is rockets, missiles and high-speed aircraft structural parts. Mid-1960s, titanium and its alloys have been applied in general industry for the production of an electrode electrolysis industry, power station condensers, oil refining and desalination heater and environmental pollution control devices. Titanium and its alloys have become a corrosion resistant structural material. Also it is used for the production of hydrogen storage materials and shape memory alloys.

  Titanium is used in the aerospace industry as an important new structural materials. The specific gravity, strength and temperature range is between aluminum and steel but with high strength and excellent corrosion resistance to seawater and ultra-low temperature performance. Mach number of the aircraft is greater than 2.5 titanium primarily uses titanium to replace steel in order to reduce the structural weight. Spacecraft using mainly titanium’s high specific strength, corrosion resistance and low temperature performance manufactures all kinds of pressure vessels, fuel tanks, fasteners, instrument straps, architecture and rocket shells. Artificial satellites, lunar module, manned spacecraft and space shuttles are also using titanium plates welded

Reprinted from Baidu Encyclopedia