I use what is called "Dendritic
D2 steel" for the blades. The word "Dendritic" comes from the
fact that as cast steel cools in the shape of a blade, diamond-hard
carbide dendrites form like frost crystals throughout the steel. Then
when a blade is sharpened, tempered, and final honed, those carbide
crystals are exposed at the cutting edge like microscopic chainsaw
teeth. The result is a tough blade that cuts longer than anything you've
probably used before. I once cut more than 400 slices off the end
of a half-inch thick piece of Manila rope with a skinner made from one
of our #22 blades. D2 is the steel
they use to make dies for stamping other steel parts. It is tough!
I routinely drop blades point first on the cement shop floor to test
their strength. All that's happened is that I have a lot of holes in the
floor. So far no point has broken or turned.
I'm using S5 shock resistant steel for my hawks and the ferroulithic
arrowheads. This is as tough as you can get. I'm actually recycling rock
drills and Jackhammer bits. I don't think there's a better steel where
impact is concerned.