Titanium is a new type of metal, titanium performance and the content of impurities such as carbon, nitrogen, hydrogen, oxygen, the purest titanium iodide impurity content is not more than 0.1%, but its low strength, high plasticity. The properties of 99.5% industrial pure titanium are: density ρ=4.5g/cm3, melting point 1725℃, thermal conductivity λ=15.24W/(m.K), tensile strength σb=539MPa, elongation δ=25%, section shrinkage ψ=25%, elastic modulus E=1.078×105MPa, hardness HB195.

High strength

The density of titanium alloys is generally about 4.51g/cm3, only 60% of steel, and some high-strength titanium alloys exceed the strength of many alloy structural steels. Therefore, the specific strength (strength/density) of titanium alloy is much higher than that of other metal structural materials, and components with high unit strength, good rigidity and light weight can be produced. Aircraft engine components, skeleton, skin, fasteners and landing gear are all used in titanium alloys.

High thermal strength

The use temperature is several hundred degrees higher than that of aluminum alloy, can still maintain the required strength at medium temperature, can work for a long time at 450 ~ 500 ° C temperature These two types of titanium alloys still have a high specific strength in the range of 150 ~ 500 ° C, and the specific strength of aluminum alloy at 150 ° C decreased significantly. The operating temperature of titanium alloy can reach 500℃, and that of aluminum alloy is below 200℃.

Good corrosion resistance

Titanium alloy works in humid atmosphere and seawater medium, its corrosion resistance is much better than stainless steel; Resistance to pitting corrosion, acid corrosion, stress corrosion is particularly strong; Excellent corrosion resistance to alkali, chloride, chlorine, nitric acid, sulfuric acid, etc. However, titanium has poor corrosion resistance to reducing oxygen and chromium salt media.

Good low temperature performance

Titanium alloy can still maintain its mechanical properties at low and ultra-low temperatures. Titanium alloys with good low temperature performance and very low gap elements, such as TA7, can maintain a certain plasticity at -253 ° C. Therefore, titanium alloy is also an important low-temperature structural material.

High chemical activity

Titanium has a large chemical activity and produces a strong chemical reaction with O2, N2, H2, CO, CO2, water vapor, ammonia and so on in the atmosphere. When the carbon content is greater than 0.2%, hard TiC will be formed in titanium alloy; When the temperature is higher, TiN hard surface will be formed by the interaction with N. Above 600℃, titanium absorbs oxygen to form a hardened layer with high hardness; The embrittlement layer is also formed when the hydrogen content increases. The depth of the hard and brittle surface produced by the absorption of gas can reach 0.1 ~ 0.15mm, and the hardening degree is 20% ~ 30%. The chemical affinity of titanium is also large, and it is easy to adhere to the friction surface.