zOwie Omega Discussion Forum

: I happen to work with 316L stainless steel
: which is also known as "surgical grade
: stainless steel". We in the
: pharmaceutical business use it to make
: product contact parts/equipment/tanks, since
: it will be subjected to harsh chemical
: environments. Here is a description of 316:
: Type 316 is austenitic, non-magnetic, and
: thermally nonhardenable stainless steel. The
: carbon content is held to 0.08% maximum,
: while the nickel content is increased
: slightly than w/ 304. What distinguishes
: Type 316 from Type 304 is the addition of
: molybdenum up to a maximum of 3%.
: Molybdenum increases the corrosion resistance
: of this chromium-nickel alloy to withstand
: attack by many industrial chemicals and
: solvents, and, in particular, inhibits
: pitting caused by chlorides. As such,
: molybdenum is one of the single most useful
: alloying additives in the fight against
: corrosion.

: By virtue of the molybdenum addition, Type 316
: can withstand corrosive attack by sodium and
: calcium brines, hypochlorite solutions,
: phosphoric acid; and the sulfite liquors and
: sulfurous acids used in the paper pulp
: industry. This alloy, therefore, is
: specified for industrial equipment that
: handles the corrosive process chemicals used
: to produce inks, rayons, photographic
: chemicals, paper, textiles, bleaches, and
: rubber. Type 316 is also used extensively
: for surgical implants within the hostile
: environment of the body.

: Type 316 is the main stainless used in the
: marine environment, with the exception of
: fasteners and other items where strength and
: wear resistance are needed, then Type 304
: (18-8) is typically used.

: tk

: RE: Yes, I also read that Rolex uses a
: different

I have always found the use of 316L to be a bit puzzling. The L refers to low carbon. This is done to improved weldability. (The carbon would react with chromium to form carbides which would leave the adjacent material depleted in chromium and therefore no longer stainless. Keeping carbon content low avoids this problem.) If the material is not being welded 316 should be as good as 316L. I wonder if they know what they are doing? The watch industry isn't really all that technical and appears to be dominated by endorcements of stars talking about things being "finely crafted."

If they really want scratch resisitance, they could use a heat treatable, martensitic stainless or 17-4 ph precipitation hardenable stainless. I have no idea if the appearance of these alloys is acceptable. That may be the reason why we don't see them.

If Rolex's alloy is just another non-heat treatable austenitic stainless, I'd say big deal.
Regards,
Manuel