The discovery of stainless steel
Long before 1900 it was discovered that the addition of nickel (Ni) and chromium (Cr) can improve the corrosion behavior of steel consisting of iron (Fe), ie improve its resistance to corrosive acids or moisture. But the steels enriched with these individual elements were still open to many requests. The crucial breakthrough was achieved in 1912 in Germany The combination of nickel and chromium in connection with a precisely regulated heat treatment obtained for the first time an optimum corrosion resistance and good mechanical properties.
In particular, the metallic luster of the steel surface was crucial for the fact that the U.S. auto industrialist Walter Chrysler in the late 1920s capped his now world famous Chrysler Building in New York with a stainless steel crowned spire. This was the first significant use of stainless steel in construction. The elaborately carved roof consists of 4,500 individual panels of this material. When 30 years later it was cleaned and checked for the first time, “the distinctive tower plates were”, as the Metalfax Magazine wrote at the time, “dark, but as good as new.” And it has not changed to this day.1)
Stainless steel is 100% recyclable; after scrapping it can be melted down and something new can be produced out of it.
The alloy ingredients
In the standard stainless steels the chromium content is at least 10.5%. Other typical alloying elements apart from chromium are nickel (Ni), molybdenum (Mo) and/or manganese (Mn) or vanadium and nitrogen. Nickel is added to increase the deformability and the stretchability and drawability of stainless steel.
Each metal has very specific characteristics
- Chromium makes steel “stainless”, by which the improved corrosion resistance is understood,
- Nickel makes steel resistant to acids,
- Molybdenum enhances the effects of chromium,
- Vanadium refines the alloy and increases the processing capability.
Stainless steel 316L
The stainless steel 316L commonly used for watch cases belongs to the 300 series and contains chromium and nickel.