Now renowned for its corrosion resistance and exceptional lightness, titanium is increasingly used in industrial applications. It is available in pure or alloyed form. Applying heat treatments to titanium parts improves not only their mechanical performance, but also their high resistance to wear. Depending on the nature of the components, certain processes are more suitable than others.
Titanium: an increasingly popular material
Titanium has been in the news for some time now, thanks to its particularly interesting physical and chemical properties. For a start, this material boasts a remarkably low density, making it much lighter than some other metals. For example, a cubic centimeter of titanium weighs around 4 grams, while a cubic centimeter of steel weighs 7.8 grams. It provides long-lasting protection and high resistance to your materials. Titanium is therefore almost half as heavy as steel, which is a major advantage in certain industrial sectors such as aeronautics, where the quest for lightness is omnipresent.
This material also has excellent corrosion resistance, making it ideal for the manufacture of cable and pipe connections installed under the sea, for example. Not only aircraft manufacturers, but also the sports and leisure industries and the medical world are increasingly turning to titanium. As well as being lightweight, high-performance and corrosion-resistant, it is also biocompatible, meaning that the human organism assimilates it perfectly and cannot reject it, unlike other alloys. As a result, more and more medical implants and even jewelry are being made from this material.
Heat treatments for titanium
Titanium actually comes in two forms: the first, pure titanium, and the second, a titanium alloy. The best-known is TA6V, which contains 6% aluminum and 4% vanadium, and is frequently used in the manufacture of sports and biomedical equipment, as well as in the aerospace industry. TA6V alone accounts for 50% of the world'stitanium alloy production.
Although these materials already boast excellent natural properties, they can also be heat-treated to further enhance their mechanical performance and resistance to various stresses. In the case of titanium, the choice of heat treatment technology depends above all on the composition of the parts.
Titanium is also often referred to asanodized,oxidized, chemically pickled or solution treated. All these treatments are applicable to titanium, so let's take a closer look at each of them.
Heat treatments for pure titanium
Heat treatments applied to pure titanium parts can serve two purposes. Firstly, the annealing technique is used to relieve the stresses exerted on the parts, with the aim of increasing their dimensional stability and minimizing the appearance of deformation. This method also helps to improve the shaping of parts, particularly during cutting and stamping, as well as their machinability.
Processing technology for titanium alloys
In the case of alloys, heat treatment of titanium can also have different effects. As with pure materials, annealing ensures stress relaxation and better machinability .
However, other methods are better suited to titanium alloys, depending on the properties required. For example, quenching and tempering help to increase the hardness and mechanical properties of metal alloys.
This result is due to the modification of the metal structure produced during processing: high-temperature solution treatment followed by quenching and hardening tempering leads to precipitate formation, which greatly enhances the mechanical strength of the part. This is known as precipitation hardening. Particularly convincing results can be observed on certain components: untreated parts with a mechanical strength of 600 MPa can see this value rise to 1,300 MPa after treatment.
However, the use of hardening and tempering on titanium alloys requires a high degree of expertise, since, if mishandled, an embrittling layer can very quickly form on the surface of the part: the alpha case. As a result, applying this treatment to a titanium alloy requires either perfect mastery of the technique, or re-machining to remove this embrittling phase appearing on the extreme surface of the part.
Nitriding as a surface treatment for titanium
It is still possible to apply surface treatments to titanium components. Nitriding involves diffusing nitrogen onto the surface of the part, resulting in the formation of titanium nitride, an extremely hard compound. Once treated in this way, the material can achieve a hardness in excess of 1500 Vickers. This method also helps to improve the resistance of parts to abrasion. Following nitriding, a titanium part therefore boasts greater hardness and abrasion resistance, as well as a better coefficient of friction.
On the other hand, nitriding in this context requires an atmosphere heated to over 800 degrees Celsius, and therefore no longer represents a low-temperature treatment, as is the case with steel, for example, where nitriding takes place at just 500 degrees Celsius. In most cases, Thermi-Lyon favors vacuum PVDor DLC vacuum deposition, which is less energy-intensive and just as effective.
The heat treatment to be applied to titanium parts therefore depends above all on whether they are made of pure titanium or an alloy. Several solutions may be appropriate, depending on the properties required: annealing in the first case, quenching and tempering in the other, or even nitriding to improve resistance to abrasion and increase hardness. This is why Thermi-Lyon offers all possible heat treatment solutions for titanium. This global approach ensures that we remain impartial and select the best technology.
Titanium properties after treatment
After treatment, high-purity titanium boasts remarkable mechanical and thermal properties. Its resistance to wear, impact and fatigue is greatly improved, offering enhanced toughness and ductility. Treatments enhance titanium's biocompatibility, making it ideally suited to medical applications. This tough material also retains excellent thermal conductivity, essential for certain demanding industrial applications. Thanks to these transformations, titanium becomes more efficient and durable in complex environments.
To find out more about heat treatment for other metals, please see our article on the subject!
