Description
904L is an austenitic stainless steel. In comparison to 316L, its molybdenum addition gives it superior resistance to most if not all common types of corrosion which makes it a good choice for rings
Industrially, it was developed to reduce the incidence of corrosion in various aggressive environments such as piping systems, pollution control equipment, heat exchangers, and bleaching systems.
There are many uses for this steel outwith its original scope where a reliable, allergen free product is required. 904|L exceeds all of the requirements demanded by the Swiss Watch industry.
Omega experimented with 904L with the PloProf dive watches in 1971-72. The inspiration came from French deep sea diving company COMEX, who used this steel in their diving bells due to superior corrosion resistance in salt water.
In 1985 Rolex also became one of the first wristwatch manufacturers to utilize 904L grade steel in its watches. Rolex chose to use this variety of steel because it takes a higher polish than other grades of steel and provides greater corrosion resistance, though it does not machine as well compared to 316L.