What is the Difference Between 904L and 316L Stainless Steel?

.Rolex Shopping Guide.
Rolex is the only watchmaker that uses 904L stainless steel instead of the industry standard 316L stainless steel in their wristwatches. While many on Rolex forums claim that this is simply a way for Rolex to differentiate themselves from competitors, it should be noted that there are differences between the two. 

photo of Rolex 904L Stainless Steel
Rolex 904L Stainless Steel (photo: Rolex)
904L stainless steel is customarily used in chemical and aerospace applications. It is highly resistant to corrosion from acids, which makes it ideal for handling chemicals. However, a wristwatch would rarely be exposed to corrosive acids to such a degree. After all, if the watch on your wrist is exposed to these acids, you would likely lose your arm in the incident, making the watch's resistance to chemicals irrelevant as you will no longer have a wrist to wear it on.

In terms of chemical composition, 904L stainless steel has a lower amount of carbon and a higher concentration of nickel and chromium and copper added in comparison to 316L. Rolex melts this stainless steel alloy twice to purify it and ensure that it will polish well.

The polish and the resistance to scratching are the selling points that Rolex uses to promote 904L stainless steel alloy that they manufacture in-house. Although the process is more rigorous and expensive, the watchmaker insists that it is superior to 316L.

Some claim that higher amounts of nickel in 904L steel could lead to allergies on contact, but anyone with a nickel allergy would have a similar reaction when coming into contact with 316L as well.

For more information on 904L stainless steel, check out my post in the Tech section.

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Rolex Oyster Perpetual Explorer II

.Rolex Models.
First released in 1971, the Explorer II built upon the legacy of the original Explorer model. In the spirit of exploration, Rolex added additional features to this model to aid in polar exploration and cave expeditions. 

The watchmaker debuted the latest model (ref 216570) at Baselworld 2011, commemorating the 40th anniversary of the Explorer II. New features include an orange 24 hour hand, large hour markers outlined in black with blue luminescence and a 24 hour fixed bezel.

The oyster bracelet and the 42 mm case (larger than the 40mm case of the previous model) come in 904L steel, brushed to give them a modern finish. The watch contains a 3187 movement, manufactured entirely by Rolex. 
Rolex Explorer II 216570
Rolex Oyster Perpetual Explorer II
The marketing for this Explorer II model boasts superior luminosity and legibility. The 24 hour hand is also an important component, allowing one to distinguish between day and night in places that may lack daylight. 

A 24 hour hand may seem like a superfluous feature for those who live in areas with regular daylight cycles, however, for those who live or work in latitudes where there is night for several days at a time, this feature would appear to be more useful. It would also help those who may be conducting research underground or in caves, where there is no natural light.

The suggested retail price for the stainless steel Explorer II model shown above is 7,700 Swiss Francs, or $8,076 US. 

The brochure for the Explorer II contains several pages featuring explorers and mountain climbers using the world as a laboratory to test the features of the timepiece over the past decades.

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Rolex Oyster Perpetual Explorer

.Rolex Models.
After decades of gaining expertise on how the Rolex Oyster Perpetual model performed under extreme conditions (including scaling the Himalayas) Rolex released the first in a series of wristwatch models built specifically for such endeavors. The Explorer model was originally released in 1953 with new features including the Twinlock winding crown that is designed as a failsafe to keep water out of the case. 
rolex explorer model black dial
Rolex Oyster Perpetual Explorer
In 2010, Rolex upgraded the iconic timepiece from a 36mm case to a 39mm case. It features a smooth bezel, black dial and the Explorer's unique hour hand design with a 3132 self winding mechanical movement equipped with Rolex's parachrom blue hairspring and Parallax shock absorber. Made with Rolex's 904L steel and featuring the oyster bracelet, this is one of the most simple and sturdy models available.

The Explorer is classic and elegant, with smooth, clean lines and a very clear display. Although many other Rolex models provide additional features that may excite buyers, this model is ideal for those with an understated but elegant aesthetic.

The suggested retail price for the Explorer (reference # 214270) is 6,200 Swiss Francs or approximately $6,503 US according to current exchange rates.

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904L Stainless Steel Superalloy Used by Rolex Since 1985

.Tech.
If you've been on the market for a stainless steel Rolex, you may have seen that the company advertises their use of 904L grade stainless steel superalloy in their wristwatches as superior to the 316L grade stainless steel that the rest of the industry uses. 

More commonly used in the tech, chemical and aerospace industries, 904L grade stainless steel was developed for chemical processing, seawater cooling, wiring and gas washing. These industrial applications make sense as the alloy has a higher resistance to corrosion in extreme conditions, however some question the reasoning behind using this grade of metal for wristwatches.

photo of rolex 904l stainless steel
Rolex 904l Stainless Steel
Rolex started using 904L steel in 1985 because it polishes well and is more resistant to scratches in comparison to 316L. It also resists corrosion due to possible salt water or acid buildup that may get trapped in the watch case for years between cleanings.

904L stainless steel has a different chemical composition than 316L. It has a lower amount of carbon and a higher concentration of nickel and chromium, with copper added to make it less corrosive and more resistant to stress cracking.

It has been reported in forums that higher nickel content in 904L steel can lead to rashes in people with allergies to the metal, however, this is disputed as 316L stainless steel would create a similar allergic reaction, thus making the point moot in comparing the use of 316L over 904L in the wristwatch industry.

Though the average person wearing a Rolex may not be battling the elements on a daily basis, the quality of sheen and higher tolerance for scratching may be a good enough reason to choose a watch made with 904L grade stainless steel over a model using 316L.

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