What is the expertise of titanium and titanium alloys?
I. Basic properties of titanium (Ti)
Titanium is a silver-white transition metal, element symbol Ti, atomic number 22. with the following significant features:
Physical properties
Low density: density of only 4.51 g/cm³, about 57% of steel, aluminum 1.6 times, is a typical light metal.
High melting point: With a melting point of 1668°C, it far exceeds that of aluminum (660°C) and most stainless steels (about 1400°C), giving it the advantage of high temperature resistance.
Non-magnetic: It is a non-magnetic metal, which is suitable for medical and electronic applications that are sensitive to magnetic fields.
Chemical properties
Strong corrosion resistance: the surface is prone to form a dense layer of titanium dioxide (TiO₂) oxide film, which is able to resist seawater, acid, alkali and chloride corrosion, even better than stainless steel. For example, the annual corrosion rate of titanium in seawater is only 0.0001 mm, which is an ideal material for ships and marine engineering.
Reactive metal: easy to react with oxygen, nitrogen, hydrogen and other elements at high temperatures, so smelting and processing needs to be carried out under vacuum or inert gas protection (such as vacuum self-consumption arc furnace smelting).
Classification and typical grades of titanium alloy
Titanium alloy by adding alloying elements (such as Al, V, Sn, Mo, Zr, etc.) to optimize the performance, according to the phase organization can be divided into three categories:
1. α-type titanium alloy
Organizational characteristics: α-phase (dense hexagonal structure) dominates at room temperature, low plasticity but good high temperature stability.
Typical alloys:
TA1/TA2/TA3 (industrially pure titanium): purity decreases in turn, strength increases, used for chemical vessels, heat exchangers and other corrosion-resistant scenes.
TA7 (Ti-5Al-2.5Sn): high temperature resistant (below 500°C), used for aero-engine compressor section parts.
Advantages: excellent welding performance, outstanding corrosion resistance.
2. β-type titanium alloy
Organizational characteristics: β-phase (body-centered cubic structure) is dominant, good plasticity, easy processing, can be strengthened by heat treatment.
Typical alloys:
TB6 (Ti-10V-2Fe-3Al): high strength (tensile strength ≥1000 MPa), used in aerospace structural components (such as aircraft landing gear).
TB2 (Ti-5Mo-5V-8Cr-3Al): ultra-high strength, suitable for extreme load scenarios such as missile casings.
Disadvantages: high smelting costs, poor high temperature stability (usually below 300°C).
3. α+β type titanium alloy
Organizational characteristics: coexistence of α-phase and β-phase, comprehensive performance balance, is the most widely used category.
Typical alloy:
TC4 (Ti-6Al-4V): the most widely used titanium alloy in the world, with high strength (tensile strength ≥ 895 MPa) and good corrosion resistance, widely used in aerospace (airplane wings, engine parts), medical (artificial joints, dental implants).
TC11 (Ti-6.5Al-3.5Mo-1.5Zr-0.3Si): high temperature resistance (above 500℃), used in aero-engine turbine disk.
Advantage: can be adjusted through the heat treatment process (such as solid solution + aging) to precisely regulate the strength and plasticity.
Core performance advantages of titanium alloys
Extremely high specific strength (strength/density)
The specific strength of TC4 titanium alloy is about 3 times that of stainless steel and 1.5 times that of aluminum alloy, which makes it suitable for manufacturing “high-strength and lightweight” components, such as aerospace vehicle frames and racing car suspension systems.
Excellent corrosion resistance
Virtually non-corrosive in seawater, wet chlorine, hypochlorite solutions, far superior to 316L stainless steel. For example, titanium condensers in coastal power plants have a service life of more than 30 years, compared to 5-10 years for stainless steel.
Good biocompatibility
Titanium and titanium alloys (e.g. TC4. Ti-6Al-7Nb) are non-toxic, non-allergenic, and the modulus of elasticity (about 110 GPa) is close to that of human bones (10-30 GPa), which makes it an ideal implantable material for medical use, accounting for more than 90% of the artificial joint market.
Excellent low temperature performance
In - 253 ℃ (liquid hydrogen environment) still maintains the toughness, not brittle, better than most steel, used in rocket cryogenic fuel tanks and pipelines.
Fourth, the main application areas of titanium alloy
Aerospace industry
The largest proportion: about 50% of titanium alloys are used in this field, mainly used in the manufacture of aircraft structural parts (such as Boeing 787 titanium alloy dosage of 15%), engine fan / compressor blade (such as CFM56 engine titanium alloy parts accounted for 25%).
Core requirements: light weight, high temperature resistance, fatigue resistance.
Medical & Healthcare
Products include artificial joints (hip joints, knee joints), spinal endoprostheses, dental implants, etc., with a global annual consumption of over 5.000 tons.
Emerging trend: 3D printed titanium alloy porous structure (e.g. Ti-6Al-4V ELI) to promote osteoclast growth and enhance implant integration efficiency.
Chemical & Marine Engineering
Used in the manufacture of heat exchangers, reactors, valves, fasteners for offshore platforms, etc. Typical scenarios include the chlor-alkali industry (Cl- corrosion resistance), desalination equipment (seawater washout resistance).
Typical examples include the chlor-alkali industry (Cl- corrosion resistance) and seawater desalination equipment (seawater scour resistance). Representative case: the oil and gas platform in the South China Sea adopts a large number of titanium alloy tubing, and its service life has been increased to more than 3 times that of traditional materials.
Energy and automotive industry
Energy: Titanium tubing is used in condensers for nuclear power plants and casing for geothermal wells (resistant to hydrogen sulfide corrosion).
Automotive: exhaust pipes and valve springs for racing cars (lightweighting to improve fuel efficiency), and titanium chassis components for the Tesla Model S.
Consumer Goods & High-end Manufacturing
Titanium eyeglass frames (lightweight and anti-allergy), watch cases (e.g. Rolex Milgauss series), golf club heads (to enhance hitting distance), and so on.
V. Titanium Alloy Production and Processing Challenges
Smelting is difficult
Titanium reacts easily with elements such as C, N, O, etc. Titanium sponge (TiO₂→TiCl₄→titanium sponge) needs to be produced by the Kroll method, and then made into ingots by vacuum smelting, which is a complicated process and consumes a lot of energy (the production of one ton of titanium consumes about 12.000 kWh of electricity).
High processing costs
β Titanium alloy has a high resistance to deformation, and requires isothermal forging (the temperature of the mold is the same as that of the billet), which is a high investment in equipment; welding requires argon protection to prevent oxidation.
Surface Treatment Requirements
Medical field needs to form TiO₂ nanotube layer through anodic oxidation (to enhance bone bonding); aviation components need to be shot peening to enhance fatigue resistance.
Sixth, the development trend of technology
Development of new alloys
Aluminum and vanadium-free alloys: e.g. Ti-35Nb-7Zr-5Ta, to reduce the risk of toxicity of the Al element and enhance biocompatibility, used in minimally invasive medical devices.
High-temperature titanium alloys: Ti-Al-based alloys (e.g., Ti-48Al-2Cr-2Nb), with a melting point of more than 1.200°C, are expected to replace some of the nickel-based high-temperature alloys for use in combustion chambers of aero-engines.
Additive manufacturing (3D printing) technology
Laser powder bed fusion (LPBF) technology can directly mold complex titanium alloy components (such as aero-engine whole blade disk), reducing material waste (traditional cutting waste rate of 70%).
Representative case: COMAC C919 airliner titanium alloy wing ribs are 3D printed, reducing weight by 30% and increasing strength by 20%.
Surface Functionalization Modification
Enhance the surface hardness to more than 2000 HV by ion implantation (e.g. N⁺, Cr⁺) for wear-resistant parts (e.g. titanium alloy bearings); or ** Chemical Vapor Deposition (CVD)** to apply diamond coatings to improve tool life.
VII. Environment and Economy of Titanium and Titanium Alloys
Resource distribution: Titanium ore reserves are abundant (mainly ilmenite and rutile), with China, Australia and South Africa as the main reserve countries, but high-grade ore (TiO₂≥50%) is scarce.
Recycling: Titanium alloy waste can be recycled through vacuum remelting, with a recycling rate of over 90%, in line with the trend of green manufacturing.
Cost comparison: the price of titanium alloy is usually 3-5 times higher than that of stainless steel (e.g., TC4 is about $120/kg, 316L stainless steel is about $25/kg), but the whole life cycle cost (lower maintenance cost due to corrosion resistance) is more advantageous.
To summarize
Titanium and titanium alloys have become irreplaceable materials in high-end fields such as aerospace, medical and marine engineering due to their unique properties of “lightness, strength, corrosion resistance and biocompatibility”. Despite the challenges of high smelting costs and processing difficulties, they are expanding their application boundaries, driven by technologies such as additive manufacturing and new alloy development. In the future, with the breakthrough of green smelting technology (such as direct electrolysis of TiO₂), titanium alloy is expected to realize large-scale popularization in the fields of new energy vehicles and deep-sea equipments, and become the “strategic metal of the 21st century”.
