Performance Characteristics Of Titanium Alloys

Titanium alloy has the advantages of low density, high specific strength, good corrosion resistance, high heat resistance, good process performance and so on, it is the more ideal aerospace engineering structure materials. It is widely used in various fields.

Titanium is a new type of metal, titanium properties and the content of carbon, nitrogen, hydrogen, oxygen and other impurities related to the content of pure titanium iodide impurity content of no more than 0.1%, but its strength is low, high plasticity. 99.5% of the performance of industrial titanium is pure: density ρ = 4.5g / cm3, melting point of 1725 ℃, hardness HB195.

High strength

Titanium alloy density is generally around 4.51g/cm3, only 60% of steel, the strength of pure titanium is only close to the strength of ordinary steel, some high-strength titanium alloys exceed the strength of many alloy steel. Therefore, the specific strength of titanium alloy (strength / density) is much greater than other metal structural materials, can produce unit of high strength, good rigidity, lightweight parts and components. Currently, titanium alloys are used in engine components, skeletons, skins, fasteners and landing gears of airplanes.

High thermal strength

The use of temperature than aluminum alloys 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; titanium alloy in the range of 150 ℃ ~ 500 ℃ still has a very high specific strength, and aluminum alloys in the 150 ℃ than the strength of the obvious decline. The working temperature of titanium alloy can reach 500℃, while aluminum alloy is below 200℃.

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 corrosion resistance is particularly strong; alkali, chloride, chlorine, organic items, nitric acid, sulfuric acid, etc. have excellent corrosion resistance. However, titanium has poor corrosion resistance to reducing oxygen and chromium salt media.

Good low temperature performance

Titanium alloy in low temperature and ultra-low temperature, can still maintain its mechanical properties. Good low-temperature performance, the gap element is very low titanium alloy, in -253 ℃ can also maintain a certain degree of plasticity. Therefore, titanium alloy is also an important low temperature structural material.

High chemical activity

Titanium is chemically active and reacts strongly with O, N, H, CO, CO2, water vapor, ammonia, etc. 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, the role of N will also form a hard surface layer of TiN; above 600 ℃, titanium absorbs oxygen to form a hard hardened layer with high hardness; the rise in the hydrogen content, it will also form an embrittled layer. Absorption of gas and the resulting hard brittle surface layer depth of up to 0.1 ~ 0.15mm, the degree of hardening is 20% ~ 30%. Titanium's chemical affinity is also large, easy to produce adhesion phenomenon with the friction surface.

Small thermal conductivity, small modulus of elasticity

Titanium's thermal conductivity λ = 15.24W/(m.K) is about 1/4 of nickel, 1/5 of iron, 1/14 of aluminum, and various titanium alloys have a thermal conductivity of about 50% lower than that of titanium. 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, and the rebound of the machined surface when cutting is very large, about 2 to 3 times as much as stainless steel, resulting in sharp friction, adhesion and bonding wear of the tool's rear blade surface.