Acmonital is a Stainless Steel alloy consisting mostly of Iron, with 0.14% Carbon, 17.5-19% Chrome, 0.50% Magnesium, 1.15% Silicium, 0.03% Sulfur, and 0.03% Phosphorus by weight. Acmonital was used in Italy for their Lira and is the acronym for "acciaio monetario italiano" (Italian monetary steel).
References
Acmonital Wikipedia(Text) CC BY-SA