What are the "Grade 2" and "Grade 5" titanium materials you hear about in the watch industry? / Mainspring Q&A - Answering your watch questions

Q: What is this Grade 2 or 5 titanium that I hear about in the watch industry?

A: Grade 2 is pure titanium, Grade 5 is titanium alloy

Titanium is a new material that began to be used in the watch industry around 1980. Lightweight, rust-resistant, and hypoallergenic, titanium is an ideal material for watches. However, it was difficult to process, so it did not become widespread. The first Japanese manufacturers to successfully adopt it for commercial models were Citizen and Seiko, both in the 1970s. In the 80s, Swiss manufacturers followed suit, also adopting titanium cases. Today, it has become a very popular material in the watch industry.

Broadly speaking, there are two types of titanium currently in use: Grade 2 and Grade 5 titanium. The former is what is generally referred to as pure titanium, while the latter is a titanium alloy containing additives. Grade 2 has the best material properties. However, because it is difficult to process and cannot be given high-quality finishes such as graining, many manufacturers now use Grade 5. Incidentally, some manufacturers, like Panerai, use different titanium for different parts of their watches. For example, the case might be Grade 2, while parts that require finishing, such as the bezel, are Grade 5.

As mentioned above, titanium is difficult to achieve a high-quality finish, so it was once said that titanium was inferior in quality to stainless steel. However, it can now be said that titanium watches made with grade 5 are almost comparable in appearance. It is also said that the material's properties are no longer significantly different from grade 2. Richard Mille is known for its luxury watches made with titanium.