Titanium alloy refers to various alloy metals made of titanium and other metals, which have high strength, good corrosion resistance, and high heat resistance. It is an important structural metal and is widely used in aviation, aerospace, naval vessels, military and medical equipment, and other civilian fields.
Since the 1950s, hundreds of titanium alloys have been developed in the world, with the most famous alloys ranging from 20 to 30, such as Ti-6Al-4V, Ti-5Al-2.5Sn, Ti-2Al-2.5Zr, Ti-32Mo, Ti Mo Ni, Ti Pd, SP-700, Ti-6242, Ti-10 5-3, Ti-1023, BT9, BT20, IMI829, IMI834, etc.
The performance of titanium is related to the content of impurities such as carbon, nitrogen, hydrogen, and oxygen. The purest titanium iodide impurity content does not exceed 0.1%, but it has low strength and high plasticity. The performance of 99.5% industrial pure titanium is: density ρ= 4.5g/cm3, melting point 1725 ℃, thermal conductivity λ= 15.24W/(m.K), tensile strength σ B=539MPa, elongation δ= 25%, reduction of area ψ= 25%, elastic modulus E=1.078 × 105MPa, hardness HB195.
Compared to traditional metals, titanium has the following advantages:
1. High strength
The density of titanium alloy is generally around 4.51g/cm3, which is only 60% of that of steel. However, its mechanical strength is equivalent to that of steel, and it has high strength, usually with a tensile strength of (686-1176MPa). The tensile strength Rm of TC4 is approximately 1262 MPa.
Some titanium alloys exceed the strength of many alloy structural steels, so the specific strength (strength/density) of titanium alloys is much higher than that of other metal structural materials, which can produce components with high unit strength, good rigidity, and light weight. The engine components, framework, skin, fasteners, and landing gear of the aircraft are all made of titanium alloy.
2. Corrosion resistance
In air below 550 ℃, a dense, strong adhesion, and inert oxide film is formed on the surface of titanium, protecting the titanium substrate from corrosion. Even due to mechanical wear, it will quickly self heal or regenerate. Moreover, when the medium temperature is below 315 ℃, the oxide film of titanium always maintains this characteristic. Therefore, in oxidizing media such as atmosphere, seawater, nitric acid, and strong alkali, titanium alloy has better corrosion resistance than most stainless steels. This is the basic guarantee for the use of titanium materials in civil industries in various countries.
3. Good high-temperature resistance
Strengthening through solid solution α The high-temperature titanium alloy developed can be used for a long time below 600 ℃ and for a short time below 800 ℃. When the aircraft's flight speed Mach number is above 2.7, the engine's disks, blades, rear fuselage, guide vanes, intake gearbox, and other components are made of high-temperature titanium alloy.
4. Biocompatibility
Titanium metal is a biometallic metal with excellent biocompatibility. It can be "compatible" with the human body or implanted in the body without causing harm to the human body. Titanium in the human body can resist the corrosion of secretions and is non-toxic, so it is adopted by the medical community for devices such as artificial joints and cardiac pacemakers.
Research has shown that titanium implants can trigger the human immune system to directly grow bones on the surface of titanium, a process known as bone integration. Titanium is completely "biocompatible", which means it is non-toxic, does not cause allergies and rejection reactions, and can even fuse with human tissues and bones.
Titanium alloy is used as a high-end material in the fields of aerospace and cutting-edge military industry. With the maturity of technology, titanium alloy, as an increasingly common metal material, has begun to be widely used in fields such as ships, chemical equipment, oceans, sports equipment, medical implants, automobiles, motorcycles, bicycles, construction, daily necessities, etc.
