[C4RL]

To keep my reply simple & clarify, the hatchet in question is undoubtedly made completely from carbon steel, if it were to be soaked in any etchant it would show a light uniform grey steel colour all over because it's cast with around an inch along the cutting edge that'll be much darker grey where it's been hardened. It's a 20th century factory head.
Quite a lot like it in this area alone (southern Spain), many still in use.

Below, the first two images are more in line with older heads, these are wraps with a small carbon steel bit welded in.
Third & fourth image a hatchet that's a wrap with a filler piece.
Fifth, a beautiful example of a wrought iron wrap with a welded in carbon steel bit fresh out of etchant (before you cry "sacrilege" for etching something so old....I can explain).
Six & seven, huge old axe heads, I put these here simply as an example of what some might describe (& possibly try to sell..) as executioners axes, or again weapons. They are in fact just (lovely) old French wood axes, nothing more!