Titanium Metal: Grades, Manufacturing Processes and Applications of Titanium Metal!
Titanium Metal Fabrication Process
The production of titanium metal is carried out by a process called the Kroll process. This process has five stages. The first stage is called extraction, the second is called purification, the third is called sponge production, the fourth involves alloy creation, and lastly, the fifth step is forming and shaping. Because every step is time-consuming and costly, no industry yet performs all five. Most industries carry out a single stage of this process. For example, some manufacturers specialize in sponge production, and others only create the alloys.
l Extraction
The first step of the Kroll process is the extraction of titanium ores. The manufacturer receives the titanium ores from mines. These ores can be in the form of ilmenite, rutile, or any other mineral of titanium. Rutile is usually used in its natural form. However, ilmenite needs processing that becomes the first step to remove the iron so that the remaining part will have 85% or titanium dioxide. For this process, these ores are placed inside a fluidized bed reactor with chlorine and carbon and are heated to an elevated temperature of 900 °C. The chemical reaction takes place, which results in the creation of titanium tetrachloride in impure form and carbon monoxide as a by-product. The impurities are present in the TiCl4 because after removing iron, titanium dioxide is not yet pure.
l Purification
In this step, the TiCl4 is put inside a large distillation tank for heating. The impurities present are separated in this step by fractional distillation and precipitation methods. These two methods remove all impurities, including vanadium, silicon, magnesium, zirconium, and iron.
l Sponge Formation
The third stage of the Kroll process is sponge formation. In this stage, the purified titanium tetrachloride is emptied into a stainless steel reactor vessel in liquid form. After the transfer, the magnesium is added to the vessel and the mixture is heated to the temperature of 1100 °C in order for magnesium to react with chlorine and produce magnesium chloride. There is a chance that oxygen and nitrogen might be present in the air, so argon gas is pumped into the vessel to remove the air to avoid any reaction with oxygen and nitrogen. The titanium left in the vessel is not pure and in solid form because the melting point of titanium is much higher. This titanium solid is now removed from the vessel by a boring process and treated with a mixture of water and hydrochloric acid. This is to remove any excess of magnesium and magnesium chloride. At the end of this stage, the titanium obtained is in sponge form, hence the name sponge formation.
l Alloy Creation
In the fourth stage, the pure titanium sponge is mixed with different alloys and scrap metals to create usable alloys with the help of a consumable-electrode arc furnace. After melting and mixing all required metals in the required proportion, the mass is then compacted and welded to form a sponge electrode. This sponge electrode is melted in a vacuum arc furnace to form ingots. These ingots are usually melted again and again to fabricate commercially acceptable ingots.
l Forming and Shaping
In the last stage of the Kroll process, the ingots are removed from the furnace, inspected for defects, then sent out to be used to create titanium alloy goods. The properties of each ingot are checked to ensure they meet the requirements of customers. The ingots go through various processes such as welding, forming, casting, forging, powder metallurgy, etc. to be shaped into the finish well. It all depends upon the specification of the required product.
Byproducts of the Kroll Process
During the Kroll process, when the titanium is separated from the impurities, a significant amount of magnesium and magnesium chloride is left behind. This by-product of the Kroll process is recycled immediately in a recycling cell. The recycling cell separates the magnesium and chlorine into their stable forms. I.e., magnesium in solid form and chlorine in gas form. The chlorine gas is collected from the top of the recycling cell, and both of these components are used again in the Kroll process.
Pure Titanium and Its Grades
Titanium in its pure form comes in various grades that are suitable for specific applications. Titanium CP4, aka Grade – 1, is the softest grade with the highest ductility, toughness, and corrosion resistance. Due to its cold forming characteristics and brilliant welding properties, it is popular in the architecture, automotive, medical, and processing industries. This grade is available in the form of bars, flanges, sheets, welding wires, and forgings.
Another grade that has excellent cold forming properties with corrosion resistance and welding propertie
s is CP3 – Grade 2. It is used in aerospace, automotive chemical architecture, marine, and medical industries.
CP2 – Grade 3 is considered to be stronger than previous grades.
CP1-Grade 4 titanium is the strongest and most corrosion resistant but has lower ductility. It is commonly used in medical and aerospace applications.
Grade 7 titanium has the best mechanical and physical properties with excellent fabrication and welding properties. It is even corrosion-resistant to reducing acids.
Grade 11 - CP Ti-0.15Pd has similar properties to Grade 2.
The following tables indicate the available standards & forms of pure titanium grades.
Titanium Products
Products made with titanium are high-performance and durable. These products include jewelry, medical instruments, scissors, and bicycle frames. For industrial products, titanium is alloyed with iron, aluminum, nickel, and molybdenum to make jet engines, spacecraft, and military hardware. It has the strength of steel with half its weight.
l Titanium Wire
Titanium wire is a common form of titanium and comes in several forms, from pure titanium to titanium nickel alloy wire. Each type of titanium wire has different uses, from glass holders to welding wire. Titanium wire has all of the properties of titanium, including corrosion resistance, strength, non-magnetism, biocompatibility, and excellent shape memory.
Although titanium wire has many beneficial properties, its major use is as welding wire for pipes, repairing turbine discs, and welding casings. Other uses include the manufacture of load-bearing springs, bearings, and fasteners.
l Titanium Bars
Titanium bar stock has an exceptionally high strength-to-weight ratio, making it ideal for applications that require strong metal support. As a light, strong, and durable metal, it is widely used for aircraft construction and sporting equipment. Titanium bar stock is available in grades 1 to 12, with grade 5 being the most widely used due to its formability, low creep rate, and resistance to corrosion cracking.
Grade 5 titanium bar stock is also the strongest of the titanium alloys because it is alloyed with aluminum and vanadium. It is often used for turbine blades, fasteners, and spacer rings.
l Titanium Foil
Titanium foil is a special form of titanium available in plates, strips, coils, or sheets with a thickness less than 0.1 mm. Due to their exceptional strength, durability, and low density, titanium foil is made from titanium grades 2 and 5. When heat treated, titanium foil becomes highly resistant to fluctuations in temperature, making it ideal for use in the oil and gas industry.
l Titanium Fasteners
There are several varieties of titanium fasteners, including different types of screws. Fasteners made of titanium are lightweight, with high tensile strength and good corrosion resistance. In addition, since they have a high melting point, they are ideal for applications involving extreme temperatures, such as aerospace and medical applications. As with titanium foil, fasteners are made of grade 2 or grade 5 titanium.
l Titanium Pipes
Titanium piping is popular due to its cost-effectiveness since it is resistant to damage caused by corrosion. Although the initial cost of titanium piping is higher than other materials, such as graphite, ceramic, and PTFE, the cost can be amortized over its long lifespan. As with many titanium products, titanium piping has exceptional strength and low density that decreases its structural weight. Unlike other piping materials, it can be configured to fit in small spaces and still retain its strength.
l Titanium Flanges
Titanium flanges are used to connect titanium pipes and split pipe networks for inspection and cleaning purposes. Grade 2 titanium is most commonly used to manufacture flanges due to its low density, making it ideal for applications where weight may be an issue. In addition, its corrosion resistance and strength are why it is used for marine applications, chemical processing, and desalination piping.
l Titanium Plates
The most outstanding characteristic of titanium plates is its strength-to-weight ratio, which makes it ideal for aircraft and spacecraft manufacturing. The five methods used to produce titanium plates are casting, forging, rolling, extrusion, and laser cutting. The choice of production process determines the exact specifications of titanium plating and the applications where it can be used.
l Titanium Rods
Titanium rods come in various forms, including square, hexagonal, and flat. The different shapes of titanium rods make them easy to store and transport. They are manufactured using forging, rolling, extrusion, casting, and spinning. Though they can be used as structural supports, they are normally melted down to create other titanium products.
l Titanium Sheets
As with titanium plates, titanium sheets are a widely used metal material due to titanium's advantageous properties. The exceptional strength of titanium makes sheets of titanium ideal for applications that require a lightweight but strong metal for protection. In addition, titanium's non-magnetic and biocompatible properties make it ideal for medical implants and aerospace manufacturing. Titanium sheets are available in various grades depending on the needs of an application. Grade 2 and grade 5 are the most commonly used, with other grades used to fit a specific application.
l Titanium Tubing
One evident characteristic of titanium tubing is how it maintains its positive properties, requires limited repair, and is long-lasting enough to offset its initial costs. Processes that involve the use of corrosive chemicals rely on the strength of titanium tubing. Additionally, fuel lines and valves depend on titanium tubing as a method of protection from corrosion, breakage, failure, and chemical leaks.
Titanium's strength, endurance, and dependability have made it highly valued for various processes and applications. The products listed here are a sampling of how this valuab
le metal has been used to enhance and improve crucial applications.
Titanium Metal Applications
l Medical Industry
Titanium plays a significant role in the medical industry because of its biocompatibility. It is a non-toxic material that has been used in many surgical tools and implants. From hip ball socket replacement to dental implants, titanium has been used in the medical industry for various purposes. These implants can stay in place for more than 20 years. The titanium implants usually contain about 4% of vanadium and 4% to 6% of aluminum.
l Orthopedic Implants made of Titanium
Titanium has an ability to Osseo-integrate, which allows us to use it in dental implants and orthopedic implants that can last for 30 years. Due to lower modulus elasticity, titanium implants allow the skeletal load to be distributed equally between the bone and implant, resulting in the reduction of bone degradation due to stress and periprosthetic bone fracture. Titanium has greater stiffness than the human bone, which can result in bone deterioration in the case of increased load.
l Pigments and Additives
Titanium is mostly refined into titanium dioxide, which is a white permanent pigment. This white pigment is used in papers, toothpaste, plastics, and paints. Paints with titanium dioxide perform better in severe temperatures and humid environments. It also serves its purpose in cement, optical opacities in papers, and gemstones. This is also added to graphite composite finishing rods and golf clubs to increase their strength. Titanium dioxide is a chemically inert compound that is resistant to corrosion and does not fade in sunlight. It also has a very opaque appearance, which makes it suitable for use as pigments in the manufacturing of the majority of household plastics. In addition to significant uses as a pigment, titanium dioxide is also used in sunscreens due to its high refractive index and optical dispersion.
l Aerospace Industry
Titanium has high corrosion resistance, high fatigue resistance, high tensile strength to density ratio, high crack resistance, and the ability to withstand high temperature. It is considered the ideal material for manufacturing aircraft, missiles, and armor plating. It is utilized in the manufacturing of critical structural parts, landing gear, exhaust ducts, firewalls, and hydraulic systems. In fact, titanium accounts for almost 50% of materials used in an aircraft. The titanium alloy used consists of aluminum, nickel zirconium, vanadium, and other elements.
l Jewelry
Titanium is durable and biologically inert, which has increased its popularity in the jewelry industry. Its inertness makes it a popular choice among people with allergies and among people who live in a humid environment. Its durability, dent resistance, light weight, and corrosion resistance make it useful for manufacturing wristwatches and watch cases. Some artists use titanium for fabricating sculptures and other decorative objects. Titanium is also mixed with gold to produce a 24-karat gold alloy, which results in an alloy harder than pure 24-karat gold. Anodized titanium has optical interference fringes and a variety of bright colors, which make it popular for body piercings too.
l Marine Industry
Titanium is a corrosion-resistant material; this makes it ideal for use in the marine industry. Naval ships' hulks are made of titanium alloys because of their corrosion resistance to seawater. Titanium is also used to manufacture propeller shafts, heat exchanges, rigging, heat chillers for saltwater aquariums, drivers` knives and finishing lines, and leaders. Additionally, it is used in housing and ocean deployed surveillance equipment and monitoring devices.
l Automotive Industry
Titanium is used in the automotive industry, particularly where low weight and high strength rigidity are required. It is also cost-effective considering metal is generally too expensive to be used in huge amounts. It is used to manufacture exhaust and intake valves inside engines because of its heat resistance and high strength.
2023 03/13