Titanium is a chemical element denoted by the symbol Ti and has the Atomic Number 22. It is transition metal with a low density but high strength and is resistant to corrosion making it suitable for use in several applications such as titanium tube and titanium sheet.
Titanium was first discovered by the English Chemist Rev William Gregor in 1791 who named the metal Gregorite. The metal was also discovered separately and at a later date by the German Scientist in M.H. Klaproth in 1793 who named the metal Titanium after the Greek God Titan with the name Titanium remaining to this day. Isolating the metal wasnt achieved until over a century later in 1910. Titanium is found in raw form in the minerals Rutile and Ilmenite which themselves make up more than 24% of the Earths crust, therefore making titanium a highly abundant material. Titanium is not however found in isolation in nature, instead it is found in combinations of Fe and Oxygen with the process to isolate requiring significant effort and as such affects the availability and cost of the metal.
The key properties of titanium which make the metal an optimal material for several applications are:
- Atomic weight of 47.867amu
- Density of 4510 kg/³ making it more than 50% lighter than Steel
- Non-magnetic
- A high melting point (m.p.) of 1650 °C
- High Passivity and so is able to withstand high levels of chlorides and acids without corrosion.
- Bio-compatible and non-toxic
Titanium Grades
Titanium Grades are typically categorised as being Commercially Pure (CP) or Titanium Alloys with the following table listing the most popular grades. Grades differ from country to country with several of the largest Titanium Production countries maintaining different specifications and standards for Titanium
| Alpha and Near-Alpha Alloys |
|---|
| Grade 9 – 3Al-2.5V |
| Grade 12 |
| Alpha Beta |
|---|
| Grade 5 – 6Al-4V |
| Grade 23 – 6AL-4V ELI |
| Ti-6Al-2Sn-4Zr-6Mo |
| 6Al-6V-2Sn |
| Near-Beta and Beta Alloys |
|---|
| 15V-3Al-3Sn-3Cr |
| Grade 19 – 3Al-8V-6Cr-4Mo-4Zr |
| 13V-11Cr-3Al |
Standard Terminology
Throughout the manufacturing and distribution supply chain common terminology is used. The terminology is not exclusive to titanium however is important to define and understand.
Products used in Fabrication
Plate – Flat rolled mill product that is normally hot finished, more than 200mm wide and 3.175mm thick.
Sheet / Strip – Have thickness between 0.635mm and 3.175mm and produced as a coil with sheets being cut to required length.
Bar – Used as references to squares, rounds, hexagons and profile shapes with cross-sections above measuring at least 9.525 in cross-section.
Wire Rod – Semi-finished wire product made for the production of wire.
Wire – Typically wire produced from cold drawing a wire rod.
Foil – Has thickness less than 0.127mm and of any width.
Tube Product – Used to describe hollow titanium product which are normally a cylinder shape like those used in heat exchanger tubes.
Rough Terminology for Products
Ingots – Are the largest form of titanium product in a cylinder form with a 1.5 length to diameter dimension ratio. The ingot are typically 86cm in diameter and 248cm long and are approximately 6tonnes
Blooms – This refers to a semi finished product either billet, slab or bar which has been formed by hammering or rolling a titanium ingot.
Billets – These are semi-finished products with a square section of titanium produced by rolling either a bloom (as above) or titanium ingot
Slabs – Semi-finished product with a rectangle cross section and where the width is double the thickness at least.
Heat Treatment
Heat Treatment – Heat treatment is the process by which the properties of metals are changed by applying heat cycles to the metal. How long the heat is maintained for certain temperature values along with the cooling cycle rate is as important as the temperature. The reason why heat treatment is performed is to change the material properties so as to make it more machine-able, increase toughness, enhance cold forming, improve ability to shear, change tensile properties and stress relive.
Annealing – Refers to the processes which involves adding heat and slow cool cycles to change toughness and ductility. The annealing process makes the titanium softer and so easily formed, machined and sheared.
Stress Relief – The action of removing “residual stress” from a metal
Quenching – Fast cooling of a metal from a high temperature usually through application of a coolant.
Grinding, Turning, Polishing – The machining processes which are typically applied to bars to enhance surface quality and precision.
Titanium Standards
Titanium production standards are country specific with a growing global adoption of the ASTM standards. The other leading titanium production standards are based on DIN German, JISC – Japan, BS – China, OTC – Russia.
| Product | ASTM | ASME | DIN | Other |
|---|---|---|---|---|
| Titanium Tubing | ASTM B861 ASTM B862 ASTM B338 |
DIN 17 861 | ||
| Titanium Bar | ASTM B348 Medical ASTM F67 Medical ASTM F136 |
ASME SB348 | DIN 17862 | OCT 1 90006-86 Medical ISO5832-2 Medical ISO5832-3 AMS 4928 AMS 2631b |
| Titanium Sheet | ASTM B265 | ASME SB265 | DIN 17860 | AMS 4902 |
Titanium Applications
Titanium can be found in applications in all industries from small titanium fasteners used in iPhone casings through to tubes in the worlds largest deep sea Heat Exchangers. Its history of usage can be dated back to military usage in aircraft and demand for the metal is still greatly influenced from the Military sector. In recent decades its usage has become more diversified as use of the material increasingly becomes used as an improved alternative for Steel applications.
Mill Form
Titanium is produced and supplied in an intermediary Mill form which are then used for further downstream stream processing. Furthermore the intermetiary mill forms are split into two categories which differ in the finished state of the material. Titanium Ingot, Billets and Slabs are the first category which are the form produced and stocked by Titanium Mills with the more refined state category being Titanium Tube, Titanium Bar & Rod, Titanium Wire, Titanium Forgings and Titanium Sheet, Coil & Plate which are commonly used by end application manufacturers.
Titanium Markets
Titanium Markets are:
- Aerospace
- Military
- Consumer
- Medical
- Energy & Industrial