Alloy steel n. Any steel containing a notable quantity of some other metal alloyed with the iron, usually chromium, nickel, manganese, tungsten, or vanadium.
... felt a cold, hard knot. Take stainless steel alloyed with titanium and plate it with three inches of lead. Take a brain made up of super-charged magnetic crystals enclosed in a leaden cranium and shielded by alloy steel. A bullet wouldn't pierce it; radiations wouldn't derange it; an axe wouldn't ... — Robots of the World! Arise! • Mari Wolf