found a great article about StayBrite steel, got me going down another road...here it is, with some timelines: http://www.sswnews.com/dyknow/ShowPage.aspx?pageId=806
I've excerpted the following:
"The British steel mill, Firth Brown, introduced this stainless steel over eighty years ago in the early 1920s to Swiss watch makers for making the cases and the straps. A 12 chrome 12 nickel steel, the StayBrite D.D.Q., became the standard material for almost 50 years. In fact, the first man on the moon, Neil Armstrong, wore an Omega SpeedMaster wristwatch made of StayBrite Steel D.D.Q. in 1969.
...In the sixties and seventies the 304 and 304L were also used for making watch cases but this quality proved less corrosion resistant and had to be replaced. In Switzerland the 1.4435 with higher nickel and molybdenum content became the standard whereas in Asia the classic 1.4404 (316L) is still used."
Classic StayBrite (as near as I can tell) is alloyed with chromium and nickel in 12%/12% "concentrations". Not nearly as corrosion resistant, as alluded to previously, but plenty hard and, as stated in various places on the net, highly "polishable" - hence it's name, popularity with watchmakers, and long life in the industry. It was also used in some of the first commercially available stainless steel flatware.
1.4435 steel is classified as 316L, and is alloyed with chromium (18%), nickel (14%), and molybendenum (3%) - from earlier posts, this steel would be very corrosion resistant, possess high "polishability", due to nickel content, but still below the threshhold of nickel allergic reaction - the nickel's bound up too tightly in solution to "leak" and cause a reaction.
1.4404 steel is ALSO classified as 316L, with chromium, nickel and molybendenum in 17%/12%/2% concentrations - still plenty resistant to corrosion, but a bit less "polishable" due to it's slightly lower nickel content (???)
Somebody with more knowledge than me should step up and tell me what a 2% difference in nickel content will do with the surface finish and "polishability" of these variants. I can't find squat.
Wonder which variant of 316L is being used by Panerai? Does the teaching staff (Hammer, Maurits, Dirk, Ferretti, (and dare I ask Bonati???)) have any input?
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