Titanium is known for being both strong and lightweight, additionally it is highly corrosion resistant. This makes titanium a very versatile material (applications), however conventional methods of polishing and deburring are less suitable for titanium. Titanium can, however, be polished to a mirror-like high gloss finish using the Electro-Plasma Polishing (EPP) process and simultaneously be deburred. For the EPP process no acids are used, therefore reducing the chance of pitting. Moreover the process is dimensionally stable so details (be it rounded) will remain intact. On this page you can find the widely used titanium types (grades) which can be processed using the plasma polishing process. For other metals and alloys please refer to the “materials” page
Unalloyed (pure) titanium
Grades 1 through 4 are unalloyed and therefore considered commercially pure (CP). These grades are distinguished by the level of impurities (interstitials). Mainly the difference in oxygen content between grades 1 (low) through 4 (high) results in an increase of tensile strength.
Grade 1 contains the highest percentage of titanium, making it the softest and most ductile (easy formable) titanium grade which also as an excellent weldablility. Therefore very useful for intricate parts in corrosive environments. Grade 1 has a relatively low strength of 34800 psi or 240 MPa.
Grade 2 has a higher percentage of oxygen (and Iron) interstitials (impurities) giving it a higher strength (50000 psi or 345 MPa). As it combines this higher strength with good ductility, cold-formability and weldability it is the most commonly used type of the commercially pure titanium grades.
Grade 3 is the least used CP grade, although the medium oxygen contents yields a higher strength of 65000 psi or 450 MPa. Characterized by high strength and good ductility, it is however less suitable for cold-forming.
Grade 4 has the highest oxygen content of the commercially pure titanium grades, making it the strongest (tensile strength of 80000 psi or 550 MPa) unalloyed type. Grade 4 has reasonable weldability, but reduced ductility and formability. It is characterized by its superior corrosion fatigue resistance in for example seawater.
Grade 5, also called Ti6Al4V, Ti-6Al-4V or Ti6-4 (Titanium 6 4) because it is titanium alloyed with 6% Aluminium and 4% Vanadium. It offers an excellent combination of strength (130000 psi or 895 MPa), toughness ductility and ease of fabrication. Add to that the strength to weight ratio, corrosion resistant characteristics and reasonably high service temperature (750°F400°C) and you have a very widely applicable alloy. The aforementioned characteristics have led to the fact that Grade 5 is the most used type of titanium.
Grade 7 (TiPd) is very similar to CP grade 2 with regard to formability and strength. Grade 7 is however more corrosion resistant due to the addition of Palladium. It is also suitable for seawater applications at higher temperatures.
Grade 11 (TiPd) is equivalent to unalloyed grade 1 with regard to formability and strength. Grade 11 has a superior corrosion resistance (in oxidizing and reducing acids) due to the addition of Palladium. Furthermore, grade 11 is also suitable for deep drawing.
Grade 23 or Ti-6Al-4V (Grade 5) ELI in which ELI is the abbreviation of Extra Low Interstitial elements, meaning it contains fewer impurities than grade 5, especially the percentages of iron and oxygen are lower. Compared to grade 5, its strength is slightly lower (120000 psi or 825 MPa). Grade 23 is however known for its biocompatibility and used regularly for medical applications.
Composition of titanium grades (values in mass percentages)