There is a blacksmithing technique called San Mai where you basically wrap a piece of higher carbon steel, for edge retention, and is wrapped into a piece of lower carbon steel, for workability and shock factors, whereas the higher carbon steel sticks out a bit from the lesser steel. Back in the day the higher carbon steel was precious and was used sparingly. I have found axe heads that are the same. I live about 5 miles from where John Deere had one of his blacksmith shops, 1830's I think. I'd like to think the ones I have found were made by him. At the historical site they have items they have found from when his shop burned down. They look like the one you have and the ones I have found. I would say 1800's for sure. Just my opinion as a part time blacksmith.