SS 316L vs. 316F vs. 904L- The final VERDICT- A technical study

[kidkindacool]

I have a V8 Noob submariner and purchased a spanking new ARF 904L brushed stainless steel bracelet to upgrade it. Due to the fact the Noob SELS were always a topic of dissapointment I figured this was a good choice in the forever chase of GEN qualities on my watch.
9/10 difference. I do think the clasp was a little better on the Noob but from a pure aesthetic standpoint 904L ARF smoked the 316L Noob.
The bracelet was brand new though so...could of been that. Either way a solid upgrade.
Just my 2 cents.

 

[xox]

that might be of interest

Both of 904L and 316L are Austenite steel which are nonmagnetic and has high corrosion resistant properties, and good machining and polishing performance. As we all know, they can be be regard as substitutes for each other in some cases. So what's the difference?




Grade 316L, the low carbon version of 316, is highly resistant to sensitisation (grain boundary carbide precipitation) and so is extensively used in heavy gauge welded components. The lower carbon content of 316L gives it an even greater resistance to corrosive environments than 316 stainless steel. Austenitic stainless steel 904L is a kind of low carbon high-alloy Austenitic stainless steel with good machinability and weldability and corrosion resistance to dilute sulfuric acid. The addition of copper makes it have strong acid resistance, especially to interstitial corrosion of chloride and stress corrosion.

Chemical Composition is the the key to study and determinate the physical properties of 316L and 904L. We are indicating the chemical composition of the two analyzed SS grades we are studying in the table below.

Grade	C	Mn	Si	P	S	Cr	Mo	Ni	Cu
316L	0.03	2.0	0.75	0.045	0.030	16.0-18.0	2.00-3.00	10.0-14.0	/
904L	0.02	2.0	1.00	0.035	0.035	19.0-23.0	4.0-5.0	23.0-28.0	1.0-2.0

As you can find in the table above, 316L and 904L steel has a similar Chemical composition in the content of C, Si and Mn, but the alloy content such as Chromium, Nickel and Molybdenum of 904L steel is much higher than 1.6 times that of 316L, and 904L steel contains a certain amount of copper, which can effectively delay the corrosion of acidic liquid, especially chloride on stainless steel, making 904L steel more resistant to corrosion and abrasion than 316L. In addition, 904L is much higher resistance to chlorides at elevated temperatures. If 904L has better corrosion resistance, Can I replace 316L with 904L? The answer is No! The higher nickel content of 904L making it is an expensive component and this will influence the overall cost .

There is no difference between 316L and 904L steel in strength and hardness. Both of them have similar Rockwell hardness (HRB) which is less than 95 and their tensile strength are both about 490MPa. These properties are specified for flat rolled product (plate, sheet and coil) in ASTM A240/A240M. The specification for pipe and bar is similar but not necessarily identical properties are specified.



Swiss luxury watch brand ROLEX first used 904L steel to make the case in 1985 and gradually make it a industry standard

 

[indywatchguy]

Now that 904 ARFs and Noobs have been around for some time- is there any more clear answer on if their 904 is legit and of the stated benefits? Given that this article states its 50-100x more expensive to manufacture (or at least used to be), what's changed to make 904 possible in reps for similar price points?

One more question - Some people seem to say visually impossible to discern between 316 and 904 while others state the sheen is different. Thoughts?

It’s simply not true! There is a visible difference between 904 and 316! Most can’t see it. I own both and the look and feel is overall better however I have really good vision and an eye for detail. I can spot flaws in diamonds without a loupe. There’s a reason more watch companies like BALL are going to 904!


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[boomerknox]

My opinion on this now 8 year old thread (as a student nearing graduation with a BSME) is there are subtle differences between 316 and 904. The vast majority of the time it is not cosmetic; if you are looking at the two side by side MAYBE you’d see a difference. If they are polished and cleaned to the same degree I (personally) don’t believe one would clearly be the “winner”. I’ve never tried this side-by-side comparison, but have experience with rep and gen pieces of both materials and can recall no defining differing characteristics. The differences are chemical and mechanical properties.

If one is (essentially) only slightly harder than the other, why choose 904 over 316? Why does Rolex choose 904?

Well, Rolex is a LUXURY manufacturer so of course they go with the more expensive choice. For many manufacturers and consumers, the cost doesn’t outweigh the benefits since it’s so much more expensive, but for Rolex it does. It’s an expensive watch so use the more expensive, more scratch resistant metal.

So why use it for a rep? I see 2 reasons: 1) you want as close to gen as possible or 2) the slightly increased scratch resistance is with the $100+ to you. If either of those is true, pull the trigger on 904! If not, the couple more desk dive marks on your 316 won’t be the end of the world


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[adamweby]

thanks for the write up!

 

[LEGASCON]

I have both 316 and 904 and both are good

The 904 L ARF is more smooth than the 316 NOOB but maybe it s a personal point of view

 

[erans007]

I have the 904 and its great!

 

[therevenant]

nice thread!

 

[TheKnight]

i work on my own watches and mod. when i work on my gen seikos i scratch them and stienharts with case back removers some times. i slipped once with my rolex explorer 1 904l and i can tell you 904l is worth it. looks mint still. 904L is amazing. and im disappointed in 316L for i dunno why it seems soft like butter

 

[seeseoh]

Impressive write up, it's very professional and easy to understand. Thanks

 

[Gfpatt]

Thanks for the write up! Most do not know the difference!

 

[WATCH HACKER]

So guys, is the Noob V9 is a real 904L?

 

[AlphaProt]

So guys, is the Noob V9 is a real 904L?

Yup. Real


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[dubhdubhdubh]

WOW this is a fascinating thread! Thanks OP and everyone who has contributed over the years!

 

[dubhdubhdubh]

316 vs 904 weight-
Hey all, fwiw this has probably been addressed by now, but I just weighed a single full link from 2 rep Milgauss, one each of 904L and 316L (at least that's how they're advertised):
904L link from DJF Milgauss, 2.79g
316L link from BP Milgauss, 2.87g
So if my terrible math skills are correct, that's about 2% difference..?, with the 316L being heavier. Verrry slightly. Screw from each was 0.26g, so probably same unknown material used by both. Hope this is useful for somebody

 

[Warrcraft]

Great write up! As for 904lL really being true, these are reps, come on, it's obviously just another ploy to get more money out of us!

 

[Watch34eu]

thanks a lot for all the information
i have heard from someone who work in a rolex factory the replica have a good 904l steel but isn't the same as gen

 

[QWERTY7888889]

Hi levelmnroger,
i trust your idea.
the rep dealer dont use any 316 type...you can easy see the difference from one original and one rep.
the shine and the brilliant are very different!!!

 

[Glaude]

the shine and the brilliant are very different!!!

The smell too !

 

[QWERTY7888889]

will be' intresting have the knowledge to understand wich metal is really inside rep