zOwie Omega Discussion Forum

thought I'd throw in my $.02 worth. The one thing that the 316 vs 316L vs 17-4 or 17-7 leaves out is the subject of magnetic attraction. We are using 316L now, instead of our original 17-7 SS, on items to be used in an MRI environment, because they are not magnetic. 316L is also less magnetic than regular 316 SS. If you look at the ASTM standards (sorry, I don't remember the standard number off the top of my head) for 316L, it explains the reasoning. 316L is non-magnetic, vs 316 which can become so during coldworking. In contrast, the 17 series are all strongly attracted to a magnet. This just might be a problem with a watch. FYI, we even discussed briefly using 904L, which is also non-ferromagnetic, but welding problems nixed that.

The reason Rolex uses the 904L is because it is less prone to corrosion in warm sea water than even the 316 or 316L, especially for crevice pitting. If I remember correctly, it has a higher percentage of chromium, and a MUCH higher percentage of nickel. The high percentage of nickel makes it a very bad choice for surgical use though. As far as I can recall, the hardness of 904L isn't significantly different from the 316L, so scratch vulnerability will be about the same.

John

: Probably comes down to cost, availability and
: machinability. As I recall, the watch cases
: are machined out of a solid block, so the
: cost of maintenance working on
: easier-to-work-with metals is a plus
: (especially for tooling). It's easier to
: finish less wear resistant metals as well,
: so it would definitely cost less than
: something that would better resist
: scratches.

: Looks like 304 would be less prone to wear than
: 316, but it is not as resistant to
: corrosion, etc. Don't underestimate the
: harsh conditions of our own bodies and
: neglect on a watch. When was the last time
: everyone washed/wiped off their watches
: after exposing it to sweat and heat? I
: remember changing my watch band on my
: DW-5600 G-Shock for the very first time in
: 13 years. There are two areas on the 304
: stainless case back that are covered by the
: band making it hard to clean (I've never
: cleaned the watch at all). Taking the watch
: bands off, I could clearly see the pitting
: caused by corrosion in exactly those areas
: under the bands.

: I'm sure some thought has been put into the
: choice of metal to use. I sometimes don't
: get the comparison between the Rolex and
: Omega bracelet wear. The Rolex finish on
: their band is nowhere near as complicated as
: that on the Omega Seamaster (especially the
: Bond watch with sections of mirror polish vs
: brushed). This makes it easier to observe
: scratches on the Bond bracelet than on the
: Sub (just by virtue of the Bond bracelet
: attracting more attention and more
: scrutiny). The Omega bracelet cross section
: is also rounded, so the highest area will
: exhibit the most wear. The Omega clasp is
: also about 740 square millimeters of blank
: canvas for scratches to be noticed, while
: the Sub's clasp is stamped to look like the
: rest of the bracelet.

: tk