Most watch companies use grade 316 L for their watches …but Rolex uses 904 L
Lets brief you why..
Firstly Grade 316 is the standard molybdenum-bearing grade. The molybdenum gives Grade 316 high corrosion resistant properties and particularly high resistance to pitting and also crevice corrosion in chloride environments. Grade 316L is the low carbon version of 316. There is not much price difference between 316 and 316L
Where Grade 904L is a non-stabilised low carbon high alloy austenitic stainless steel. The addition of copper to this grade gives it greatly improved resistance to strong reducing acids, particularly sulphuric acid. It is also highly resistant to chloride attack – both pitting / crevice corrosion and stress corrosion cracking. It is also non-magnetic in all conditions. Further, it contains substantial content of the high cost ingredients nickel and molybdenum.
Advantage of 904L over 316L?
It’s not a higher grade of steel, merely a “different” grade. All that extra chromium and nickel simply means that it has better resistance to corrosion and pitting than 316L and that it is a more heat treatable steel to harden, to be used in dies, punches, bending and blanking equipment. So in fact, 904L is a “tool steel” much like how Rolex were first made to be “tool watches”. 904L steel is only more expensive because it is not as popular in general application as 316L.
Nickel content of 904L is two times that of 316L, Also 904L is not as common as 316L, and is expensive.
Chromium 19% – 23%
Molybdenum 4% – 5%
Nickel 23% – 28%
Chromium 16% – 18%
Molybdenum 2% – 3%
Nickel 10% – 14%
Rolex used to use the same steel as everyone else, but in around 2003 they moved their entire steel production to 904L steel.
In 1988 they released their first 904L steel watch with a few versions of the Sea-Dweller.
904L steel is more rust and corrosion resistant, and is somewhat harder than other steels. Most important to Rolex, is that 904L steel, when worked properly, is able to take (and hold) polishes incredibly well. If you’ve ever noticed that steel on a Rolex watch looks different than other watches, it is because of 904L steel, and how Rolex has learned to work with it.
The 904L Rolex uses a VAR grade, (Vacuum Arc Remelt). The remelting removes inclusions and impurities in the steel, it’s referred to as “cleaner” steel. This is done by the steel provider at the mill. Typically VAR steels are used in parts subject to fatigue, the cleaner steel improves fatigue life, VAR steel grades are common in tools, bearings and aerospace applications.
We feel the another advantage of the 904L is it’s formability, meaning it cold forges easier than 316L which makes it easier to shape. Rolex will not have to replace the forging dies as frequently and can possibly reduce the number of steps required to manufacture the case.
Watchbazar feels that although other watch manufacturers use 316L surgical quality stainless steel, Rolex sets itself apart by using a slightly harder, more chemical resistant steel that is yet another quality that sets Rolex into a different category watches of watches.
Happy Reading …………