Choosing the right metal for your application is crucial to ensuring a finished product that is not only able to serve its intended purpose but that also meets all safety specifications. Titanium is a popular metal that is used in applications across a variety of industries due to its favorable properties. This is your guide to titanium's properties, uses, and manufacturing.
What is Titanium?
Titanium is a common element that is found in the Earth's crust. It’s atomic number is 22 on the periodic table of elements. The 2 primary minerals which contain titanium, are Rutile and ilmenite which make up 24% of the earth’s crust. This leads to Titanium being the 9th most abundant Earth metal and is typically found in rocks and sediments.
Ti is a transition metal, which means that it can bond using electrons from multiple energy levels. The metal is silver in color, of low density, and high strength. The name originates from the word 'Titan' which comes from the Greek Mythology beings known as 'Titans', which were extremely strong and resilient.
The History of Titanium
Titanium was unknowingly first discovered in 1791 by a geologist Rev. William Gregor. He found an interesting substance in a creek bed and after analyzing it, found that it was a mixture of magnetite, iron oxide, and a new metal.
4 years later, a German scientist by the name of Martin Heinrich Klaproth was studying the components of an ore and realized that it had a new metal in it. He named it titanium and later made the connection that Gregor's sample contained titanium as well.
Pure titanium was first produced by Matthew A. Hunter, an American metallurgist, in 1910. Later, in 1932 Titanium metal was first used outside the laboratory setting when William Justin Kroll proved that it can be produced by reducing titanium tetrachloride (TiCl4) with calcium. Eight years, this process was refined with magnesium and sodium.
In the 1950’s and 60’s the Soviet Union pioneered the use of this amazing metal in aerospace and defense applications during the Cold War and were it’s largest producers. While on the US side, titanium was considered a strategic material which extended throughout the period of the Cold War by the U.S. government. The government, namely the Defense National Stockpile Center, maintained a large stockpile of titanium sponge until it was finally depleted in the 2000s.
Titanium is an amazing material which has unique properties that make it highly sought after in the production of many modern and innovative applications. It’s strong and light. The tensile strength of Ti is between 30,000 psi to 200,000 psi depending on the type of titanium. It is also low density; about 60% the density of iron, reducing load and strain of heavier metals while reducing the overall weight of the objects it is used to manufacture. Titanium actually has the highest strength-to-density ratio of any metallic element.
The melting point of Titanium is much higher than Stainless Steel. This, combined with its low weight and high strength, are why Titanium and titanium alloys are used in airplanes, missiles and rockets where strength, low weight and resistance to high temperatures are important.
Titanium has excellent elasticity, exhibiting a Young's modulus equivalent to approximately 50% of stainless steel which makes it desirable for certain spring applications.
It is also extremely desirable in medical manufacturing because titanium metal is one of the most biocompatible metals that exist, leading to its use in everything from artificial joints to cardiac valves and other surgical implantable devices.
The thermal expansion rates of titanium and titanium alloys are generally equivalent to approximately 50% of stainless steel. This means that there is less dimensional change induced by heating the metal when compared to Stainless or Aluminum. This, combined with its superconductive properties lends well to use in devices such as induction motors and semiconductor manufacturing.
Some other properties of Titanium include:
- Excellent heat transfer properties
- High melting point - 3,135 degrees Fahrenheit (This is 400 degrees above the melting point of steel and 200 degrees above that of aluminum)
- A high degree of resistance to minerals, acids, and chlorides
- Non-toxic - Makes it a candidate for use in medical devices that are inserted in the human body
- High-degree of electrical resistance
Concerns of Titanium
Since titanium is so strong, it can be difficult to cast. It also has high reactivity, which means it must be closely managed during every phase of manufacturing. Compared to other metals, titanium tends to be more expensive because of its valuable properties and the time and resources it takes to produce it.
How is Titanium Produced?
In nature, Titanium only occurs in chemical combinations; the most common of which are oxygen and iron. In order to reach a finished product, titanium must go through several different processes to reach a finished product. The number and type of processes vary depending on the intended final application. However, no matter what the desired product is, titanium must first be separated out from the ore and turned into pure titanium. This is called the Kroll Process.
The Kroll Process
- The ore begins in a fluidized bed reactor which produces purified titanium oxide.
- The purified titanium oxide is then oxidized with chlorine to produce titanium tetrachloride.
- The impurities are then fractionally distilled.
- The product is then moved into a stainless steel reactor where it is mixed with magnesium in an atmosphere of argon. Titanium 3 and titanium 2 chlorides (TiCl2) are the results of this step.
- Titanium 3 and titanium 2 are then reduced to produce pure titanium and magnesium chloride.
From start to finish the Kroll Process takes several days to complete. The final product is a titanium "titanium sponge" which is then ready to undergo further processing which ultimately can be manufactured into bars, plates, sheets, wires, or whatever your application calls for. Here is what the chemical reaction looks like as an equation: TiCl4+2Mg=>Ti+2MgCl2
Once sponge has been produced, the process continues with the melting of titanium sponge, or sponge plus the master alloy. This is done to form an ingot. From there the material moves to primary fabrication where an ingot is converted into general mill products such as billet, bar, plate, sheet, strip, and tube; and then secondary fabrication of finished shapes from mill products.
The History of Titanium Re-Rolling at Ulbrich
The story of titanium at Ulbrich is both a fascinating case and an applicable example of how our dedication and commitment to materials capabilities development can support continual success.
In the early 1980's Ulbrich embraced the aerospace market with its flight recorder tape, a thin nickel-based alloy foil product which was used for decades with great success. With growing innovations within commercial and defense application, the need for titanium foil was growing as a result of these engineering breakthroughs.
At this time, however, supply chains were limited. Titanium was typically only supplied in sheet, plate, and bar form, using hot rolling and vacuum annealing to create final product. Cold rolling, cleaning, and continuous annealing were limited, if not non-existent.
The key point of entry into titanium, for Ulbrich, occurred in the late 1980's with our first established customer program for continuous Grade 9 titanium strip. We supplied titanium metal to the aerospace market and many subcontractors involved in developing and producing commercial and military airframes. The aerospace market had a growing need for titanium coiled strip and foil for the structural components fabricated to protect these airframes' engine components. As a result of the dedication of our in-house metallurgists, Ulbrich developed a supply chain to purchase small rolls of titanium starting material, cold roll the metal inside our facility.
This was a challenge for us, to say the least. Titanium behaves very differently than stainless steel and nickel alloys. Our production was forced to adapt to the difficulty of producing titanium, developing new techniques and investing in new capabilities to deliver titanium metal product that met ours and our customer's expectations. Many capabilities in both the rolling process and annealing process were made possible through the development of technology and installation of new equipment. This combined with the investment in several other technologies and a deep cultural commitment by our entire organization to push the bounds of what was before considered impossible allowed our titanium strip to be produced with a higher level of quality and efficiency than ever before.
Small win, after small win, helped build confidence within the company which led to even further developments to help establish Ulbrich as a key partner for titanium strip across multiple industries. Over time we refined our process and positioned ourselves to take on the next generation of titanium demands.
Types of Titanium and Their Applications
There are various types of titanium that are suitable for different applications based on their strengths and properties.
Titanium dioxide is also known as titanium oxide and comes in a fine white titanium powder. It gives products a bright white hue. It is created when titanium naturally interacts with oxygen. This form of titanium is extremely popular in everyday products such as paper, plastics, sunscreen, toothpaste, cosmetics, paints, and even adhesives.
Titanium Alloys and Applications
An alloy is a metal that contains the primary metal, in this case, titanium, with a small percentage of other elements. Titanium alloy still has high strength and corrosion resistance properties. However, thanks to the other metals it also has increased malleability. This means that it has more applications than pure titanium. Here are some grades of titanium alloys Ulbrich works with:
- Grade 5 Titanium - This is the most common titanium alloy and is most commonly used in aerospace parts, sports equipment, and marine applications.
- Ti Grade 9 (Titanium 3-2.5) - This alloy is a compromise between the facility of welding and manufacturing of the pure grades and the high strength of Grade 5. Containing 3% Aluminum and 2.5% Vanadium, it has great corrosion resistance and can be used extensively in aerospace, chemical processing, medical, marine, automotive.
- Titanium Beta 21S - This alloy is one of the beta titanium alloys which was developed as an oxidation-resistant aerospace material and as a matrix for metal-matrix composite
- Titanium 15-3-3-3 - This alloy is a metastable beta titanium alloy that offers substantial weight reductions over other engineering materials if used In the solution treated condition. It has excellent cold formability.
Commercially Pure Titanium Grades and Applications
Commercially pure titanium means that the finished product only contains the element titanium and isn't mixed with any other components. This type of titanium has the highest corrosion resistance of any form of titanium. The distinguishing characteristic of CP Titanium is the percent of oxygen content that acts as the primary strengthening mechanism for these metals. It also has exceptional malleability properties. There are 4 grades of pure titanium.
- Titanium Grade 1 - This is the softest form of pure titanium with a high degree of weldability and high ductility. It is most commonly used in the architecture, medical, and marine industries. Grade 1 has the lowest oxygen (O) % allowance of any of the commercially pure grades. With each increase in grade comes an increased oxygen allowance.
- Titanium Grade 2 - This variation features moderate strength and a high degree of malleability. It oxidation and corrosion-resistant. Grade 2 is most commonly used in architecture, automotive parts, aerospace, and desalination.
- Grade 3 Ti - This type of pure titanium is stronger than the grades above it, but also less malleable as well. It is popular in hydrocarbon processing, aerospace, and marine industries.
- Grade 4 Ti - is stronger than grades 2 and 3. It also has a lower ductility, but very high corrosion resistance properties. It used in applications where a high degree of strength is a must including the medical industry and the aerospace industry. Grade 4 has the highest oxygen (O) % allowance of any of the commercially pure grades.
Quick Titanium Guide:
|Category||Typical Chemical Compositions||Properties|
|Commercially pure titanium||JIS class 1 to 4|
ASTM GR 1 to 4
|Good formability (Grade 1)|
Relatively high strength (Grade 4, TS=700MPa)
|Metastable β type titanium alloy||Ti-15-3-3-3||Age-hardenability|
|α type titanium alloy||Ti-5Al-2.5Sn||Good creep resistance|
|α + β type titanium alloy||Ti-6Al-4V|
High corrosion resistance
|β type titanium alloy||Ti Beta 21S||Great creep resistance|
The Right Titanium for Your Application
Ulbrich specializes in precision metals across a variety of industries. No matter what your application needs are, our expertise combined with state-of-the-art methods ensures that the finished product will not only meet but exceed your needs. Contact us today and let our team help you with your project applications!