On the drawings I see daily, it's referred to as O1. There are tool steels with other designations that we use as well: A2, D2, H13. Of course, everyone here also knows that when you say "Drill Rod", you're generally meaning O1.
O1 is common and readily available in lots of different shapes here. It isn't the nicest stuff to harden with a torch, as it has the tendency to warp after quenching even if you're careful. This may be fixed with tempering, but for our uses we don't bother with that step. I've noticed a very slight size increase after hardening most of the time, but this wouldn't be of concern in a cutting tool.