Leaderboard

From: 'THE VINTAGE ROLEX FIELD MANUAL' CHEVALIER EDITION The stainless steel used in Oyster cases is an alloy recipe made from iron ore, chromium, nickel, molybdenum, and a few other trace elements. These trace elements give the iron ore its stainless, corrosion-resisting properties. Metallurgists call this alloy “300 Series Austenitic Stainless Steel”. 316 stainless steel is considered standard marine grade stainless steel. Despite the name, it is not resistant to warm seawater corrosion (specifically, chloride, fluoride, iodide, and bromide). 304L and 316L (316L is the low carbon version of 316) are derived from this 300 Series and are used in many pre-1987 vintage Oyster cases. Later Oyster cases use 904L steel with subtly different properties. The common misconception is that 904L is harder and more scratch-resistant. The fact is, 316L has a higher Rockwell Hardness Rating (HR B 95) than 904L (HR B 7090), and 316L is also more scratch resistant and tougher to mill than 904L. It’s said to hold a better polish as well. 904L does, however, have better salt and acid resistance. In the mid-1980s Rolex adopted 904L as a solution to pitting and crevice corrosion. This is a common problem on Oyster mid-cases of sport and tool watches. It was first used on the transitional Submariner Date ref. 168000.