Special steel developed by ThyssenKrupp for submarine outer hulls, used by the German Navy from the U-boat class 206 up to the world’s most advanced non-nuclear submarines of class 212.

The cases of our U-series diver’s watches are made entirely of this special steel. The strength of this non-magnetic steel exceeds 155% of the commonly used AISI 316L steel for watch cases.

Another advantage of this steel for diver’s watches is its exceptional seawater resistance. Standard case steel should be rinsed with freshwater after seawater exposure, as long-term contact with saltwater under unfavorable conditions may cause corrosion. Submarine steel, however, is completely resistant to prolonged seawater contact. Additionally, due to its ductility, submarine steel is extremely crack-resistant, further enhancing operational safety.