Grade 5 titanium is a titanium alloy strengthened with aluminium and vanadium. It is the best-known titanium alloy and the grade used most often in high-end watchmaking, for cases and bracelets. It is strong for its weight, resists corrosion and keeps its finishing well. It also resists scratches much better than Grade 2.
What is Grade 5 titanium made of?
Grade 5 is titanium with aluminium and vanadium added. Metallurgists call it an alpha-beta alloy, because it contains two phases, known as alpha and beta. Each added element has its own job. The aluminium keeps the alpha phase stable. The vanadium keeps the beta phase stable. Heat treatment can change how much of the metal is in each phase. It can also change how the microstructure is arranged.
Not to be confused with
Grade 2 titanium is the commercially pure grade, with no aluminium or vanadium added. Its properties are weaker than those of Grade 5. On a watch, the difference matters. Grade 5 is very strong, at about 1000 MPa, and it resists scratches much better than Grade 2. It also keeps its finishing well. And Grade 5 can take a high-quality polish, which Grade 2 cannot.
Where it comes from
The invention of Grade 5 is credited to Stanley Abkowitz, a metallurgist who worked at the US Army’s Watertown Arsenal Laboratory. The alloy is valued for two things: high strength relative to its weight, and strong resistance to corrosion. It stands up so well to seawater that it is widely used in marine applications, well beyond watches.
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