Titanium: Definition, Characteristics, Grades, and Applications
Learn more about this material including its benefits how it can be used in manufacturing.
Titanium is a silvery-white metal valued for its high strength, light weight, and corrosion resistance. Its unique and desirable properties have led to its use in numerous industries and applications, primarily in the aerospace, automotive, medical, and chemical processing industries. Several grades and alloys of titanium exist, and each alloy type has unique properties that make it suitable for particular applications. This article will define titanium and describe its characteristics, discuss its different grades and alloys, and explain the applications in which titanium is used.
Titanium is a silvery-white metal with atomic number 22. It is a lightweight, ductile, strong, corrosion-resistant, and biocompatible metal with a high strength-to-weight ratio. Titanium is the 9th most abundant element on Earth. It is commonly found in rocks, clay, and sand. Rutile and ilmenite are the two primary commercial minerals from which titanium is extracted and refined. Titanium is classified into alpha-alloys, beta-alloys, and alpha-beta alloys. Titanium alpha alloys are alloyed with only oxygen, often alloyed with other metals, such as aluminum, molybdenum, and vanadium. The addition of these metals helps obtain desirable properties such as improved strength, corrosion resistance, and reduced weight. Common applications of titanium and its alloys include: commercial and aerospace applications, condensers in power plants, desalination plants, marine applications, architectural products, medical implants such as joint replacement hardware, and consumer goods like golf clubs and bicycle frames.
Titanium was discovered in 1791 by William Gregor, an English chemist, and mineralogist, and named by Martin Heinrich, a German chemist, in 1795. Klaproth named the element “titanium” after the Titans in Greek mythology. However, it wasn’t until 1910 that pure titanium was obtained. M. A. Hunter, a scientist working at Rensselaer Polytechnic Institute, isolated the metal by heating titanium tetrachloride (TiCl4) with sodium at high pressure and temperature (1292-1472 °F), generating pure titanium and sodium chloride as a byproduct. Then, in 1932, William Justin Kroll isolated titanium by reducing TiCl4 through fractional distillation with calcium, and later with magnesium and sodium. Today, the “Kroll Process” is the process frequently used for commercially producing titanium.
Titanium is sometimes referred to as the “Wonder Metal” or the “aerospace metal” because of its numerous desirable properties for aerospace applications. Titanium’s low density, ductility, tensile strength, and corrosion resistance all contribute to its nicknames.
The chemical symbol for titanium is “Ti”.
Titanium is not found in its pure form in nature because of its tendency to react with oxygen. Instead, titanium is found in practically all rocks, clay, sand, and minerals on Earth in the form of titanium dioxide. Rutile and ilmenite are the two primary minerals used for the commercial production of titanium. Anatase, perovskite, brookite, and titanite also contain titanium. Each of the minerals described above can be refined to obtain pure titanium.
The Kroll Process is the most common method used to produce pure titanium. The process begins with heating ores such as rutile or ilmenite to produce liquid titanium tetrachloride (TiCl4). Then, the TiCl4 liquid is purified by fractional distillation (similar to the fractional distillation process used to produce gasoline from crude oil). After distillation, molten magnesium is added to the liquid TiCl4 resulting in a porous, titanium “sponge” and a magnesium-based salt. The titanium sponge is then compressed and melted in an arc furnace. Finally, the pure titanium is cast into ingots. Alloys can be made by mixing the pure titanium melt with other metals before casting into ingots.
The properties and features of titanium differ depending on the grade and the particular alloy. However, some general characteristics of titanium are shown in the list below:
- Corrosion Resistant: Titanium is highly resistant to corrosion from seawater, chlorine, and many other corrosive agents, making it useful in marine, and chemical processing applications.
- Lightweight: Titanium has a low density compared to many other metals. It is ideal for use in lightweight structures and components in the aerospace and automotive industries.
- High Strength: Titanium’s strength rivals that of steel. A titanium structure of equivalent strength, however, weighs approximately 45% less than the corresponding steel structure because of titanium’s lower density. Because of its high strength and high strength-to-weight ratio, titanium is often used in aerospace, automotive, medical, and marine applications.
- Biocompatible: Titanium is considered the most biocompatible metal due to its inertness, its resistance to corrosion by bodily fluids, its capability to integrate into bone (osseointegration), and its high cyclic fatigue limit. This makes titanium useful in bone, joint, and dental implants.
- Heat Resistant: Titanium has low thermal conductivity. This makes titanium ideal for high-heat applications in machining, spacecraft, jet engines, missiles, and automobiles.
- Nonmagnetic: Titanium is nonmagnetic, but becomes paramagnetic in the presence of a magnetic field.
- Ductile: Titanium is a ductile metal whose ductility improves with increased temperatures. Additionally, alloying titanium with other ductile metals like aluminum significantly improves its ductility.
- Low Thermal Expansion: Titanium has a low coefficient of thermal expansion. At extreme temperatures, titanium will not expand or contract as much as other materials such as steel. Its low thermal expansion properties make titanium ideal for structural applications that experience high temperatures such as in aerospace and spacecraft or large buildings and skyscrapers in the event of a fire.
- Excellent Fatigue Resistance: Titanium has excellent fatigue resistance. This makes titanium ideal for aerospace applications where structural parts of aircraft such as landing gear, hydraulic systems, and exhaust ducts are subjected to cyclic loading.
Titanium has a silvery-gray or silvery-white color. However, titanium can achieve the full spectrum of color if anodized in specific ways. By controlling the voltage during the anodization process, different colors of titanium can be achieved.
Titanium is commonly found in igneous and sedimentary rocks and minerals. Ilmenite (titanium-iron oxide) and rutile are the two minerals from which titanium is commonly extracted. Ilmenite is a grayish-black rock, while rutile is a dark brown to black rock with a crystal-like appearance. Figure 1 below shows the appearance of a pure titanium sponge after these minerals are refined:
Pure titanium sponge.
Image Credit: https://en.wikipedia.org/wiki/Titanium
There are several different grades and alloys of titanium. The list below describes some common grades of titanium in more detail:
Grade 11, also known as CP Ti-0.15Pd, is commercially pure titanium, similar to Grade 1 and Grade 2. Grade 11 provides enhanced crevice corrosion resistance due to added palladium. It also has high ductility, impact toughness, and weldability. Grade 11 is commonly used in chemical processing and storage, ducts, pumps, and heat exchangers.
Grade 12 titanium, also known as Ti 0.3 Mo 0.8 Ni, is a durable, corrosion-resistant, and thermally stable titanium alloy that is valued for its weldability and formability. Grade 12 titanium alloy contains up to 99% titanium, 0.6-0.9% nickel, 0.2-0.4% molybdenum, up to 0.3% iron, up to 0.25% oxygen, and other elements. Because of its durability and resistance to corrosion, Grade 12 is commonly used in marine components such as ships or offshore drilling platforms, chemical manufacturing, and in heat exchangers.
Grade 4 titanium is the strongest commercially pure titanium. Grade 4 titanium’s strength rivals that of stainless and low-carbon steel, which makes the material a lighter-weight alternative. Because of its strength and corrosion resistance, Grade 4 is commonly used in aerospace, chemical processing, and marine components such as airframe structures and heat exchangers.
Grade 5 is the most commonly used titanium alloy. It accounts for around half of all the titanium used in the world. It has exceptionally high strength, heat resistance, ability to be heat treated, formability, and corrosion resistance. Grade 5 is also known as Ti 6Al-4V due to the percentage of aluminum and vanadium in the alloy. Grade 5 titanium contains 88-90% titanium, 5.5-6.75% aluminum, 3.5-4.5% vanadium, and trace amounts of other elements including iron, oxygen, carbon, and hydrogen. Because of its properties, Grade 5 titanium is highly sought after in the aerospace industry to fabricate engines and structural components. Additionally, Ti 6Al-4V is often used in automotive parts like springs and exhausts and medical applications like joint implants..
Grade 7 is a titanium alloy that is nearly identical to Grade 2 titanium. The only difference between Grade 7 and Grade 2 is the addition of palladium in Grade 7 alloys. The composition of Grade 7 titanium is 99% titanium, 0.12-0.25% palladium, 0.3% iron, 0.25% oxygen, and other elements. Grade 7 has the highest corrosion resistance of all titanium alloys and exhibits excellent weldability and forming properties. Because of its excellent corrosion-resistant properties, Grade 7 titanium is often used in chemical manufacturing and desalination applications.
Grade 1 is the softest and most ductile pure titanium grade. Therefore, Grade 1 titanium possesses the best formability out of the different types of titanium. Grade 1 titanium is composed of 99% titanium, 0.2% iron, 0.18% oxygen, and trace amounts of other elements such as nitrogen, carbon, and hydrogen. It is often used in plating, piping, tubing, and other applications where formability and weldability are critical, such as in the aerospace, automotive, and power generation industries.
Grade 3 is the least commonly used pure titanium grade. Grade 3 is stronger than Grade 1 and Grade 2 titanium, but also has slightly less ductility and formability. Grade 3 is commonly used in cryogenic vessels, condenser tubing, heat exchangers, and other chemical processing equipment.
Grade 6 titanium is a titanium alloy containing approximately 5% aluminum, 2.5% tin, and 0.5% iron. The addition of aluminum and tin improves titanium’s creep resistance and temperature stability. Grade 6 is preferred for higher service temperatures around 900 °F where it is often used for casings and rings in turbine engines, structural members and frames in aircraft, and chemical processing parts.
Grade 2 is another commercially pure titanium and is the most commonly used commercially pure grade. Like other commercially pure titanium grades, it contains 99% titanium but differs from other pure grades in that it contains 0.3% iron, 0.25% oxygen, and trace amounts of other elements. The larger oxygen percentage allows Grade 2 titanium to be stronger than Grade 1. Additionally, its ductility and weldability make Grade 2 a highly versatile alloy. Grade 2 titanium is often more affordable than other grades of titanium because it is produced in large volumes for widespread uses. Grade 2 titanium is often used in power generation and petroleum industries as a lining material due to its corrosion resistance.
Grade 23 titanium, also known as Ti 6Al-4V ELI due to its chemical composition, has high tensile and yield strength, toughness, ductility, and weldability. It has a composition of 88-90% titanium, 5.5-6.5% aluminum, 3.5-4.5% vanadium, 0.25% iron, 0.13% oxygen, and other elements. Grade 23 is considered a more pure version of Grade 5 titanium and is often the best choice for dental and medical applications. Therefore, Grade 23 titanium is often used in bone and joint replacements, surgical staples, ligature clips, tooth implants, and more.
Grade 5 (Ti 6Al-4V) titanium is the most versatile grade of titanium due to its wide range of desirable properties. It has high strength and ductility and is also corrosion-resistant, thermally stable, and highly formable. Its properties enable Grade 5 titanium to be ideal across a broad scope of industries and applications: from automotive and aerospace parts to sporting goods and consumer products.
Grade 5 (Ti 6Al-4V) titanium is the one used for 3D printing. Grade 5 is best for 3D printing because of its high strength, excellent formability, and thermal stability. Powder bed fusion 3D printing methods like selective laser melting, electron beam melting, and direct metal laser sintering are used to 3D print titanium. These processes consist of selectively melting titanium powder that has been precisely laid onto a print bed. A powerful laser or electron beam melts the titanium powder and fuses it with the preceding layers of printed material to build completed parts.
Commercially pure titanium costs roughly $18-$20 per kg while titanium alloys cost approximately $70-80 per kg.
Grade 2 titanium is the cheapest grade of titanium since it is the most widely used commercially pure titanium grade. Its wide use leads to high production volumes that reduce its price.
Titanium grades 2 and 3 are both suitable for anodizing. Anodizing is an electrochemical process that creates a protective oxide layer on the material’s surface.
The properties of titanium are listed below:
- Electrical Resistivity: Titanium’s electrical resistivity ranges from 51 μΩ/cm (Ti-0.8Ni-0.3Mo) to 198 μΩ/cm (Ti-8Al-1Mo-1V).
- Thermal Conductivity: Titanium’s thermal conductivity ranges from 6 W/m*k (Ti-6Al-2Sn-4Zr-2Mo) to 22.7 W/m*k (Ti-0.8Ni-0.3Mo).
Some of the physical properties of titanium are listed below:
- Density: Titanium’s density is 4.506 g/cm3.
- Strength: The strength of titanium depends on the grade of titanium and the concentration of its alloying elements. The strength of titanium ranges from 240 MPa (commercially pure Grade 1) to 1241 MPa (Ti-10V-2Fe-3Al alloy).
- Color: Titanium has a lustrous, silvery-white color.
- Ductility: Titanium ductility ranges from 6% elongation (Ti-3Al-8V-6Cr-4Zr-4Mo) to 25% (Commercially Pure Grade 1).
- Durability: Titanium is highly durable and has a long expected life due to its high tensile yield strength, hardness, and excellent fatigue resistance.
Some of the chemical properties of titanium are listed below:
- Oxidation Potential: Titanium has an oxidation potential due to its electron configuration and its classification as a transition metal. Because of its high oxidation potential, titanium is not found in its pure form in nature and is instead found as oxides in rocks and minerals.
- Ability to Form Alloys: Titanium can easily form alloys with other metals and elements due to its atomic size and its classification as a transition metal. Many different titanium alloys exist.
- Reactivity: Titanium is reactive to acids, and halogens at high temperatures and entirely non-reactive to bases.
- Corrosion Resistance: Titanium is naturally corrosion-resistant due to its tendency to react with oxygen and nitrogen. The formation of oxides on the surface of titanium protects the underlying material from corrosive agents.
The properties of titanium make its use common across a wide range of industries and applications. Some applications of titanium are listed below:
Titanium is commonly used in jewelry to make piercings, wristwatches, necklaces, rings, and other items due to its durability, light weight, and corrosion resistance. Additionally, titanium is sometimes mixed with gold to make 24-karat gold alloys which are harder and more durable than pure gold alternatives. Because of its biocompatibility, Titanium is popular among people who have allergies to other metals often found in jewelry, such as nickel.
Titanium is a highly critical metal in the medical industry due to its high strength, fatigue resistance, and biocompatibility. Titanium is often used in surgical and dental tools, implants, and joint replacements. Osseointegration, the ability of a bone and artificial implant to form a structural and functional connection, is possible with titanium. Titanium’s biocompatibility and non-toxicity enable better patient outcomes and durable and strong implants and prosthetics that can last up to 30 years.
Titanium is commonly used in a broad range of industrial environments due to its high strength and fatigue resistance, corrosion resistance, light weight, and durability. Uses of titanium in industrial settings include heat exchangers, tanks, reactors, valves, pipes, connecting rods, pumps, and more.
Titanium is a great choice for the manufacture of aerospace parts and vehicles and accounts for nearly 50% of the total weight of an aircraft. It is often used to manufacture critical parts such as landing gear, firewalls, and hydraulic systems. Titanium is valued in the aerospace industry because of its low density, high strength-to-weight ratio, corrosion resistance, and fatigue resistance.
Titanium is ideal for architectural products due to its light weight, high strength, corrosion resistance, and durability. While steel is still preferred to titanium when it comes to building frames, titanium is often used for glass frames, facades, roofs, interior wall surfaces, and ceilings due to its corrosion resistance and high strength-to-weight ratio.
Titanium-based composites are recently developed materials that utilize titanium’s strength and weight characteristics to produce titanium fiber-reinforced or particulate (powder) reinforced composites. Titanium composites exhibit higher stiffness, wear resistance, and strength than conventional alloys. While titanium composites have only been developed since the start of the 21st century, they are beginning to be implemented in aerospace and automotive applications.
Titanium is often used in the automotive industry to make engine parts, crankshafts, valve seats, connecting rods, exhaust systems, suspension systems, and automotive frames. Titanium is highly coveted in the automotive industry due to its low density, high strength-to-weight ratio, corrosion resistance, and heat resistance. Not only do these characteristics of titanium enable improved aerodynamics and performance, but its low density and high strength also lead to a more cost-effective manufacturing process since less material is used to satisfy particular applications.
Titanium is often used in the chemical processing industry due to its corrosion resistance and chemical inertness. While the reactivity of titanium significantly increases at higher temperatures (>700 °F), titanium is generally unreactive and stable at lower temperatures. Titanium is often used in pipes, flanges, tubing, tanks, pumps, and heat exchangers.
Some of the benefits of titanium are listed below:
- High Strength: Titanium has excellent strength and is one of the strongest metals on the periodic table. It has an exceedingly high strength-to-weight ratio, even more so than aluminum. Its strength and its low weight make titanium a popular option in many industries and applications.
- Corrosion Resistance: Titanium is naturally resistant to corrosion due to its readiness to react with oxygen. Titanium oxide forms on the surface of the part when it is exposed to air. This titanium oxide layer protects the rest of the material from corrosive substances and environments. Its corrosion resistance makes titanium ideal for use in construction and marine applications.
- Biocompatible: Titanium is nontoxic and biocompatible with both humans and animals. Hence, titanium is often used in the medical and dental industry, where it is used for implants and surgical and dental instruments.
- High Melting Point: Titanium has a melting point of around 3,034 °F. This makes titanium ideal for high-temperature applications such as jet engines, rockets, power plants, and foundries.
- Versatile Fabrication Methods: Though titanium is an exceptionally strong metal, it is soft and ductile. This enables titanium parts to be fabricated from a wide range of manufacturing processes including machining, forming, rolling, casting, and welding.
Some of the limitations of titanium are listed below.
- Reactive at High Temperatures: Titanium is generally unreactive and inert due to its protective oxide layer. However, titanium is reactive at high temperatures (>700 °F). This makes the fabrication of pure and alloyed titanium tedious and highly controlled. Titanium production must be performed in a carefully controlled oxygen-free environment.
- Expensive: Refining raw rocks and minerals to obtain pure titanium is expensive and complex. This is due to titanium’s reactivity at high temperatures and the breadth of processes within the Kroll process needed to isolate titanium.
- Difficult to Machine: Titanium can be difficult to machine due to its low thermal conductivity. The heat generated during machining builds up in the tool rather than the workpiece. This can lead to reduced tool life and machining quality.
- LowUnstable Creep Resistance: Titanium has low creep resistance at high temperatures above 570 °F. Creep is the slow deformation of a material when subjected to constantly applied loads and is more prevalent in high-temperature environments.
Yes, titanium is rust-proof. Rust is iron oxide. It is created when iron interacts with the air. Titanium contains no iron, and therefore, does not rust. Unless titanium is exposed to acids at high temperatures, titanium does not corrode because a tightly adherent titanium oxide layer is formed on the surface of titanium when it reacts with the air. The layer of titanium oxide protects the underlying titanium from corrosion due to acids, alkalis, saltwater, and other substances.
Yes, titanium is considered a paramagnetic metal. This means titanium is attracted to externally applied magnetic fields, but not to the same degree as ferromagnetic materials like iron, steel, and nickel.
Yes, titanium is metal. Like other metals, it has a lustrous appearance, is a good electrical and thermal conductor, and is ductile. For more information, see our guide on Metalloids.
Yes, titanium is bulletproof when it comes to handguns and guns used for hunting. However, titanium is not bulletproof when it comes to high-powered, armor-piercing, military-grade weapons.
Titanium and aluminum are two metals on the periodic table that are commonly alloyed and used in a broad range of industries. The primary differences in various properties and costs between the two metals are shown in Table 1 below:
Heavier (4500 kg/m3)
Lighter (2712 kg/m3)
Lower (170 to 480 MPa)
Higher (200-600 MPa)
Higher (230-1400 MPa)
Lower (170-1100 MPa)
Lower (17.0 W/m-K)
Higher (210 W/m-K)
Higher (3000 – 3040 °F)
Lower (1220.7 °F)
This article presented titanium, explained what it is, and discussed its various applications. To learn more about titanium, contact a Xometry representative.
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