It's 440B, but variations in carbon make it edge towards C according to the foreman... Standard is 0-1 which is good but very "rusty"... I can concur there's nothing like it under use...: Only Lile's D-2 so far has proven able to sustain heavy chopping on wood at around 10-12 degrees per side on a thin 0.020" edge shoulder: I've seen many other 440C blades fail on wood at this angle, even with edges two or even three times as thick, and they routinely do micro-chips or wire edges, or even crumbling, and also one big blade in S30V was twice as thick, more open in angle, and did a wire edge in a few chops... The Randall hollow grind sinks effortlessly into wood, so this might make the blade more stable, and so make the edge seem disproportionately stronger...
I don't like the rough finish, so I Cerakoat all the Randalls I care about. The 18 style blades are more loosely made, unacceptably dull-pointed, and the welded guard or blade can be askew: Watch for things out of true on the 18 blades, and even heat-curving... The Model 12s and Clintons are more finely made, so are well worth the extra cost.
Gaston