1, high strength - titanium alloy density is generally in 4.5g/cm3 or so, only 60% of steel, pure titanium strength is close to the strength of ordinary steel, some high-strength titanium alloys more than many alloy structural steel strength. At present, the aircraft engine components, skin, fasteners and landing gear, etc. are using titanium alloys.
2, high thermal strength - the use of temperature than the aluminum alloy a few hundred degrees higher, in the medium temperature can still maintain the required strength, can be in the temperature of 450-500 ℃ for long-term work in the two types of titanium alloys in the range of 150 ℃ ~ 500 ℃ still have a high specific strength, and aluminum alloy at 150 ℃ than the strength of the obvious decline. Titanium alloy working temperature of up to 500 ℃, aluminum alloy is below 200 ℃.
3, good corrosion resistance - titanium alloy in the humid atmosphere and seawater media work, its corrosion resistance is far better than stainless steel; pitting, acid corrosion, stress resistance is particularly strong; organic items such as excellent corrosion resistance. But titanium has a reducing oxygen and chromium salt media corrosion resistance is poor.
4, good low temperature performance Titanium alloy in low temperature and ultra-low temperature, can still maintain its mechanical properties. Good low-temperature performance, very low gap element titanium alloy, such as TA7, in -253 ℃ can also maintain a certain degree of plasticity. Therefore, titanium alloy is also an important low-temperature structural materials.
5, chemical activity - titanium's chemical activity, and atmospheric O, N, H, CO, CO2, etc. to produce a strong chemical reaction. Carbon content greater than 0.2%, will be formed in the titanium alloy hard TiC; higher temperature, and the role of N will also form a hard surface layer of TiN; above 600 ℃, titanium absorbs oxygen to form a hardened layer of high hardness; the hydrogen content rises, but also the formation of embrittlement layer. Absorption of gas and the resulting hard brittle surface layer depth of up to 0.1 ~ 0.15 mm, the degree of hardening is 20% ~ 30%. Titanium's chemical affinity is also large, easy to produce adhesion with the friction surface.
6, small thermal conductivity, small modulus of elasticity titanium thermal conductivity λ = 15.24W / (m.K) titanium alloy products for nickel 1/4, iron 1/5, aluminum 1/14, and various titanium alloys than the titanium coefficient of thermal conductivity of the titanium conductivity of about 50% down. The modulus of elasticity of titanium alloy is about 1/2 of steel, so its rigidity is poor, easy to deform, not suitable for making slender rods and thin-walled parts, the rebound of the machined surface when cutting is very large, about 2-3 times as much as stainless steel, resulting in sharp friction, adhesion and bonding wear of the tool after the cutter surface.
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