A Second on the D-2 nix. Not a good forging steel or a razor steel.
Start forging with simple steels. 1084, 1080, 1075, 1070 are my favorites. 52100 is OK for forging, as is 1095, but they have other issues in HT that are more complex. Aldo's 1084 ( sometimes called 1084FG) is made to forge. Another good forging steel is Cru-forge-V.
To learn to forge first, don't start on a knife.
Just start by learning what the hammer does to the hot steel. To learn forging, plain mild steel from HD or Lowes is good. You shouldn't start on a knife.
Only work the steel hot. It should be orange-red to yellow-orange to start with, and you stop hammering when it is plain red. Forging range on most steels is 1600F to 2200F.
Use the peen to make the bar longer, then try making it narrower ( like making a hidden tang), then work on how to compress the tip back to make it rounded. What I do to teach hammer technique is give a 3/4" square bar of 1070, and first have them make a round bar from it. Then they make it square again, then the make it a flat 1.5X1/4" bar. Then we start making a knife from it.
Don't expect perfect results. It takes time to learn forging skills.
Tip - When you start to forge the bevels, the blade will curve up like a banana. To counter this, start by curving it down a good bit. Then as you forge in the bevels, it will lift up to be straight ( more or less).
Other tips:
Power does not replace skill. A knowledgeable smith with a 2# hammer can move more steel than a novice with an 8# sledge. Take the time to learn how steel moves and how hot it needs to be to work right. Most people forge steel far too cool. This is why you want to start with a simple steel and preferably with square bar or round bar. You will learn so much more in a couple hours with those than trying to shape a 1/4"X2" bar of steel into a knife with no skills.
Put the blade billet back in the forge when it isn't moving under the hammer easily. It is a lot easier to forge hot steel.
When working from bar stock, plan on the final blasé size and allow a little extra for grinding the edge and spine clean. Forging rarely leaves perfect surfaces. You will have to grind the dings out of the bevels, and grind the spine and edge straight and dent free. If planning on a blade that is about 1/8" thick and 1.5" wide. start with 1" by 1/4" stock. Forge the blade and bevels to about 3/16 by 1.75" and grind the final blade clean from that. You should end up right at 1/8" by 1.5".
When you put the blade in the forge, take that time to wipe off the anvil face of any scale. You don't want to be beating the scale into the hot blade. Always forge on a clean anvil.
Have a heavy wire brush at the anvil, and brush the red-hot blade before each forging heat. This knocks off the scale on the blade. Brush/wipe off the anvil as needed if a lot of scale comes off in a forging heat.
Make your like easy. Only forge what you need to forge. A hack saw can cut the tip off at a 45° angle, and a grinder can shape a handle. What blade forging mainly does is shape bevels to prepare them for filing/grinding.
When done forging for the day, normalize the blade/billet. Heat to bright red and let cool to black ( about 900F). Repeat a time or two. The last time, when it gets to black, water quench to rapidly cool off. The blade is now softened and stress relieved.
Last and biggest tips:
At some point in learning the billet/blade will slip out of the tongs or start to fall off the anvil. DON'T try to stop/grab/move it . Just let it fall. If the grass or the floor gets scorched, that is OK. You won't remember this caution when it happens, but you will remember it when you stick your burned fingers in your mouth.
NEVER, never, forge with a wet/damp glove. If you grab a hot bar of steel, it will turn the moisture into steam and burn the H@!! out of your hand. If you gloves get wet, put on a dry pair.
Mostly, just have fun learning to forge. It is my opinion that you should make some fun and decorative things first, before making a knife. Make a plant hanger to hang a pot from a tree limb. Twist some 1/4"X1" flat stock and make pretty curlicues. Make some hot dog/marshmallow roasters from 1/4" square stock...and twist the shafts. Make coat and hat hangers. Make hooks/brackets for the shop wall to hang belts on.
