Best steel for forging a knife

Hello,

I am relatively new to blacksmithing. I have a good 150lb Peddinghaus anvil, a small Farrier’s forge, and a lot of machining equipment (I’m a machinist playing at blacksmithing really).

I have a couple of nephews that want to make “weapons of steel”. A big dagger or short sword perhaps. Doesn’t have to pretty. I tried buying some A2 air hardening steel that is 1/8" x 1 1/4" in cross section, cut off a 12" length, and started heating and hammering it. My forge is big enough to heat up the entire piece a good shade orange. But before too long the steel simply broke through into two pieces!

I’m wondering if I chose the wrong steel, or if my heating / hammering technique needs to be different somehow. Did the steel cool and harden on me? Do I have to keep it really hot and avoid hitting it once the color dulls? Or maybe there’s an easier steel to work with?

I’ve had some success forging mild steel. Tapering and curling round bar etc. I was quite surprised by this.

Any advice is most welcome. Thanks.