The 904L Steel Alloy Used in Watch Cases

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The 904L Steel Alloy Used in Watch Cases
L'alliage acier utilisé dans des boîtes de montre

Technical sheet for the 904L Steel




According to a 2006 Rolex advertisement entitled: "SOME STEEL IS MORE AMBITIOUS THAN OTHERS: Only Rolex uses 904L steel for its steel watch cases. 904L is a super alloy usually reserved for the chemical industries, where maximum resistance against corrosion is essential. Such resistance stems from 904L's higher chromium content, which forms a thin, impervious barrier on the alloy's surface when exposed to oxygen. In the event of a scratch, the chromium oxide barrier fills and protects it immediately, effectively reducing propensity of the scratch for corrosion. 904L steel is so hard that Rolex even had to develop special equipment to machine it. A mighty 250-ton press is necessary just to stamp out a single oyster case from a solid block of 904L. When it comes to ensuring the lasting beauty of your watch, no measure is too extreme for Rolex." According to Charles Newgas, who is considered a reliable source and moderator of the Timeszone.com, both the Rolex stainless steel watch heads (cases) and the bracelets are constructed of the 904L alloy.