G'day Bob
I am a bit of a cheap Ba%#@%&# from Australia. If you are going to someday sell your knives and want to garentee them. Only use new steel. Any of the listed steel is good.
If you just want to get a bit of practice up and experience with a hammer any old bit of steel will do. I make letter openers out of nearly anything. They are letter openers because there is not enough carbon in the steel to hold a cutting edge.
I have used old railway spike which are 100 years old made from wrought iron and old 5/16 wire. I put an animal head on the end flatten a blade clean it up on a wire wheel and that is it ready for xmas presents. I sell them $20 each as well. The local art gallery marks them up to $35.
It is a good simple forging fix. Make something start to finish in less than an hour. I make them in batches now I forge 6 or 8 in a 2 hour session them clean them up for about 2 hours.
For rough old knives any old car spring steel either flat or coil spring will hold a good edge for knives or hawkes. Only problem is there may be stresses in the steel. You would have to tell people what the blade was made from in case it broke. I have never seen it hapen to a blade. The forging would generally bring the problem out while forging. I have seen coil and flat springs snap while still attached to the vehicle so it must happen.
If you want a couple of sketches/photos on how I forge up my animal head letter openers send me an email.
reg_ellery@optusnet.com.au
don't miss out the _ between the reg and the ellery.
Also make the subject line say "blade forum" if I see a name I don't recognize I will zap it to avoid viruses. I had a bundle of them when the last worms were going around. If I see blade forum I will open them up. Same offer goes to anyone interested. I don't have a site to post tutorials.
EDIT: I also make letter openers out of half horse shoes. Very quick. I cut them in half forge a rough blad and hollow grind with a course belt $25 thanks for comming. With your shoeing expertise no problem.