Vintage Saturday: Trench Armor

German dugout w grabenpanzer armor
This dugout has a particularly high mustache and bayonet density (photo from Drake Goodman)

Interestingly, one of the German troops in the front row is wearing grabenpanzer steel armor. This was reportedly used primarily for machine gun crews and sharpshooters – soldiers whose jobs were particularly heavy on staying in one place and being the target of lots of fire.

Incidentally, does anyone have a good knowledge of the metallurgy of this armor? I am getting a reproduction set from IMA to do ballistic testing on, and I would like get some idea for how close it is to the originals in functional terms. Any documented information on composition, hardness, etc would be much appreciated!