Hi, in the Encyclopedia under armor type theres rolled and I guess this is meant to be Rolled Homogenous Armor, RHA.
But theres also concrete-enforced. Is this meant to be FHA, face hardened armor?
No, "face-hardned" has two types, all are face hardened but with different technologies.
Concrete-enforced - is "German style" armor, saturation of the surface layer of carbon and alloying elements - nickel, manganese, molybdenum and etc.
Rolled, face-hardened - thermal treatment of the surface by a particular algorithm.
Result is the same, but different technologies used.