This page describes in short one way to make a simple axehead. This axe was done from two pieces: a lowcarbon steel chunk to which the eyehole was pierced and a carbon steel bit, which was forgewelded to the edge of the axe.
On this medium sized Viking tool axe I started out with a 100x30x40mm (4x 1,2 x 1,6 inches) piece of lowcarbon steel. I drilled a row of holes to guide the chisel - A straight eye is nice to start out with (It usually gets crooked one way or the other at some point of forging anyways) I welded the "axe" to a sturdy rod for easy handling during the forging.
First I chiselled open the line of holes. It's a good idea to forge pieces of this size at a yellow heat. The hotter the steel the less time and blows it takes to make it. The chisel is quite long and has rounde edges so it opens an initial oval eye hole as it sinks in.
Here's the piece after chiselling.
Next I drove a larger mandrel in using heavy blows (a friend with a sledgehammer is the preferred instrument) A low anvil helps too.
The axe at this point.
Then I started to form the body of the axe to what I wanted the design to be. First we gave the steel some sledgehammer on the horn of the anvil to stretch out the neck and the butt to get those typical sharp points started at the sides of the eyehole. Here Teemu Malmi is giving a hand with the sledgehammer.
Next I widened the blade by peening it. (once again with a little help from the sledger)
Then I peened down the sides of the eye. The mandrel was in the eyehole again, otherwise it would've been messed up.
Some stretching of the blade with powerhammer and touching up with hammer and anvil and the basic form was ready. Next I opened up the blade in the middle with an anglegrinder, formed a 1% carbon steel piece to fit the shape of the blade and stick it in. Here's the axe at this point.
Next I forgewelded the edge to a solid mass trapping the carbon steel in the middle. (The next two pics are of another axe, sorry)
Then I proceded to rough grinding the axe to a final shape getting the desired angles to the edge. In this case I wanted to get rid of the hammermarks and scale, so I cleaned the whole axe with a belt sander.
Here's the axe after these stages, just before heat treating. At this point I left a millimeter or two to the edge for sharpening to take care of.
Next hardening to oil and tempering to light brown color then sharpening and sanding to final satin finish. Here's the little beast after hafting.