ROLEX steel 904L not the best;(

[time]

Hi all Rollie-lovers!

904L steel from Rolex seems to be the best watch steel ever...however, it is not. The hardness of the Rolex 904L is ~490HV(Vickers) and the "common" watch steel 316L is ~400HV.

But did you know some manufacturers use steel with >700HV, even 1200HV and 1500HV!!!! The 1500HV steel beats the 904L on the DS SD easily... since a 1500HV steel case without the "Rolex SD gas esc. system" can dive to 2000m without any problems!

Sad "news" for Rolex SD!

[WaltherPPK]

Vicker's hardness does indicate some important properties of a pressure (or watch) case, such as its resistance to abrasion. However, while there are many steels that can be tempered to greater hardness than 904L, it is difficult to find stainless steels that resist crevice corrosion in oxygen-deprived areas such as o-ring grooves. 904L does this very well.

There are other properties of any material that also are important (Yield strength, Ultimate Tensile strength, corrosion resistance, Elastic modulus, etc). Machinability has a large effect on cost, and hard steels can become very difficult to machine unless they are hardened after machining. Post-machining hardening can only be so aggressive, since it does cause distortion.

Hey, at least your steel watches aren't hollow like the gold/platinum ones! :D

[Downing]

Next time I'm at -2000m I'll keep that in mind!

[SPACE-DWELLER]

Admittedly, the tegimented "U-Boot Stahl" that Sinn uses is much harder!

[Skippy]

Originally Posted by time

Hi all Rollie-lovers!

904L steel from Rolex seems to be the best watch steel ever...however, it is not. The hardness of the Rolex 904L is ~490HV(Vickers) and the "common" watch steel 316L is ~400HV.

But did you know some manufacturers use steel with >700HV, even 1200HV and 1500HV!!!! The 1500HV steel beats the 904L on the DS SD easily... since a 1500HV steel case without the "Rolex SD gas esc. system" can dive to 2000m without any problems!

Sad "news" for Rolex SD!

The gas escape has nothing to do with diving deep but has to do with decompressing wher helium is used. If you take a watch into a decompression chamber helium gets trapped inside the watch and wants to get out. If you don't have a decompression valve on your watch the crystal will pop out or something else if this is weaker. So without the decompression system the sd would be able to go just as deep but the diver won't have to think about it in decompression chambers like a diver without thi feature on his watch would and should leave the watch outside the chamber to prevent it from getting damaged.

[mfer]

Also, there are other complications with extremely hard materials. They can crack and can be weaker under pressure, like let's say the ocean...

I took a "Material Properties" class in college for my chem eng degree (which I don't use!!!!! )

[nikhsub1]

The steel that Rolex has chosen to use, 904L, was not chosen just for its hardness... it has superior corrosion resistance and has proven to be ultra durable for its intended purpose. Rolex also likes the 'sheen' and luster properties of 904L.

[BigHat]

To say any material is "not the best" because of one attribute is somewhat naive. There are a host of attributes desired. As any systems engineer will tell you, the optimized whole often requires sub-optimized parts. 904L is hard enough and making it harder while losing other important characteristics would be a BIG mistake.
I know a number of you have read about the passion Rolex brings to its selection of raw materials in WatchTime. You think they'd hold back $5-10 of material cost on a $5,000 watch? I think they use 904L because it's the optimized SS for watches in the environs they suspect it may operate in.

[redshirt1957]

I now understand why Rolex watches are so darn expensive. They have to buy and melt these down for their stainless steel!

Behold the Porsche 904.

[MrClean]

Originally Posted by WaltherPPK

Vicker's hardness does indicate some important properties of a pressure (or watch) case, such as its resistance to abrasion. However, while there are many steels that can be tempered to greater hardness than 904L, it is difficult to find stainless steels that resist crevice corrosion in oxygen-deprived areas such as o-ring grooves. 904L does this very well.

There are other properties of any material that also are important (Yield strength, Ultimate Tensile strength, corrosion resistance, Elastic modulus, etc). Machinability has a large effect on cost, and hard steels can become very difficult to machine unless they are hardened after machining. Post-machining hardening can only be so aggressive, since it does cause distortion.

Hey, at least your steel watches aren't hollow like the gold/platinum ones! :D

interesting comment to make re "machining before hardening" - we mfgr an object from 4140 chromemoly that we have to harden or rather, source it already hardened, as hardening after machining causes distortion -

suspect reason rolex chose 904, as others have stated above, was based on a myriad of reasons peculiar to their application

[vjb.knife]

Originally Posted by MrClean

interesting comment to make re "machining before hardening" - we mfgr an object from 4140 chromemoly that we have to harden or rather, source it already hardened, as hardening after machining causes distortion -

suspect reason rolex chose 904, as others have stated above, was based on a myriad of reasons peculiar to their application

Well except for the fact that 904L is an austenitic Stainless steel and is not 'hardenable' where 4140 is.

[vjb.knife]

Originally Posted by Skippy

The gas escape has nothing to do with diving deep but has to do with decompressing wher helium is used. If you take a watch into a decompression chamber helium gets trapped inside the watch and wants to get out. If you don't have a decompression valve on your watch the crystal will pop out or something else if this is weaker. So without the decompression system the sd would be able to go just as deep but the diver won't have to think about it in decompression chambers like a diver without thi feature on his watch would and should leave the watch outside the chamber to prevent it from getting damaged.

The HRV has nothing to do with any of this discussion and your analysis of it's application is not quite right please refer to this thread.

http://www.rolexforums.com/showthrea...ght=saturation

[MrClean]

"Post-machining hardening can only be so aggressive, since it does cause distortion."

in other words, confirming what orig poster had commented, as our item requires a pretty high RC

[vjb.knife]

Originally Posted by nikhsub1

The steel that Rolex has chosen to use, 904L, was not chosen just for its hardness... it has superior corrosion resistance and has proven to be ultra durable for its intended purpose. Rolex also likes the 'sheen' and luster properties of 904L.

Exactly right. Although I think the main reason was the high polish / sheen / luster that can be obtained more than other properites which are only marginally better than 316L in this application.

The hardening comments are not applicable to this discussion either because 904L is an austenitic steel and is not and can not be hardened like 4140.

The increased corrosion resistance of 904L over 316L is mainly at elevated temperatures in very low Ph solutions which would quickly kill a diver wearing the watch so that is not that much of a big deal either.

[JJ Irani]

Originally Posted by Downing

Next time I'm at -2000m I'll keep that in mind!

Wearing different Rollies for over 27 years.....tried squeezing the hell out of each and every one of them.....and the 904L steel held up each time!!

[NitroRacer]

Just out of curiosity, how many of you actually scuba-dive to these depths? I went snorkeling of the Grand Cayman islands, once, but that's about it. How many dive at all?

[Skippy]

Originally Posted by vjb.knife

The HRV has nothing to do with any of this discussion and your analysis of it's application is not quite right please refer to this thread.

http://www.rolexforums.com/showthrea...ght=saturation

Great and very good explanation on the HRV. I didn't know that other manufacturers had ways to keep the helium completely out of the watch or that hey used rings to keep the crystal in place(do wonder if this is as good as the HRV method). I also wonder witch Seiko dive watches have the protection from the helium as I was interested in getting a Seiko diver myself to use as a daily beater(now use a G-Shock but would like one of these SKA 371 models all though I probably would never dive with it I just wan't to know out of technical interest)
I'm just a novice at this thing but I do see lot's of people that think a HRV is needed to make a watch be able to go deeper witch is not. I also understood from the post by the starter that he asumed the same and that the other watches didn't need a hrv because the steel was stronger/harder, so that's what this had to do with the discussion from my part.

Seiko SKA 371 is the one on the right:

[RW16610]

Originally Posted by Downing

Next time I'm at -2000m I'll keep that in mind!

Lol To me it is ideal, they obviouslty did their homework before making that step and in response to the original post the over engineering comes in VERY handy in my eyes for day to day wearing situations. A little extra security / insurance was never a bad thing.

[fear]

Originally Posted by JJ Irani

Wearing different Rollies for over 27 years.....tried squeezing the hell out of each and every one of them.....and the 904L steel held up each time!!

That's pretty funny!

[Perdu]

For practical (real world) purposes I don't think there is any real difference between 316L and 904L although it is smart marketing. I was not aware of the added luster qualities - I'll have to compare my watches side by side.

[haakon59]

Just because 904L is not the hardest steel available doesn't mean it is not the best mix for the purpose of wearing a wristwatch. In the end, I am sure it's a judgment call, as well as a financial one.

[nikhsub1]

One thing is for sure, the sheen (or luster) or a brushed SS rolex bracelet has a look about it that no one else can match. It almost has a halo-ish glow to it. I attribute this to the 904L and its high nickel content?

[Dalton]

I've worked with many types of steel and 904L is the best in my book. It's easy to work with and it has the necessary strength and flex to withstand the weight of any ocean as long as you're within it's limits. Also, 904L is non-magnetic vs' other steels which can be magnetic, even though they claim to be non-magnetic, or as some will call it anti-magnetic. Steel is a tricky science.

[chevycorvette]

Originally Posted by Downing

Next time I'm at -2000m I'll keep that in mind!

then, i will have to wait for u on the surface, help

[mickeydainish]

I took my 16610 to a whopping 16.5 meters with scuba gear for 45mins.... and it came up still tickin!!!! Awsome.... :-) I dont plan to try that again......

[diamondgirl]

[rescue7]

I think Rolex would know which S/S to use for there watches.
Corrosion protection is something I'd be more concerned with especially when it takes 250 tons to stamp out a single case or half a million pounds.
That's gotta be worth a few atmospheres.

[mickeydainish]

I agree mostly... I have had a bit of 904L experiance in the Pulp and Paper industry... and it's corrosion resistance and weld-ability was very highly rated. I trust Rolex in their decision... there are many factors... and I am sure their choice suits their product... but is not necessarily the best material out there. :-)

[Andad]

I would stick with 18K gold because while the hardness is only 17HV - 22HV depending on the mix, the chemical resistance leaves any stainless for dead.

[mickeydainish]

Originally Posted by directioneng

I would stick with 18K gold because while the hardness is only 17HV - 22HV depending on the mix, the chemical resistance leaves any stainless for dead.

He he.... True..... :-)