more interesting if it included which steels play nice when bieng forge welded together, to which I can suggest plain carbon steel in the form of a used horse shoe, and 5160 in the form of a vdub coil spring.
Used air ride springs yield large bilets of 5160, that I use for tongs and die blanks, stiff stuff
coil springs from trains are another large diameter stock, and torsion bars are also sometimes large, round, AND , pre tapered if someone is dreaming of a claymore to wave around.
the problem with a lot of the more exotic steels is that they are "hot short" meaning that they will litteraly just crumble and fall apart if forged at too high a heat, and at too low a heat, they are impossible to forge, so heat controll must be good, and there is no time to waste either
as each heat does some hurt to the metal, so aprenticing with cheap but good spring steel is the way to go.On the flip side there are some steels that are "cold short" and cant be touched
durring a dull or black heat.
working with strikers is good fun, and you can move a lot of metal with 4 people, one with a 4 pound hand hammer, and three with 12 pound sledges, draw out blanks in a jiffy