Please excuse the minor hijack here. David, I realize this is an awfully broad question, but how would you compare the carbon steels you mention with some of the softer stainless steels such as AUS-6, AUS-8, 12C27, 420HC, etc., as far as being fine-grained, easy to sharpen, capable of holding an edge, etc.?
Thanks,
Andrew
Most fundamentally, higher carbon content is what allows steel to be hardened to a greater degree, and therefore is what makes for better edge-holding. Heat-treat is equally important in that regard. In ascending order of carbon only (low to high), these steels might be ordered like this: 420HC < AUS-6 < 12C27 < AUS-8 < CV < 1095.
The biggest differences otherwise, between the carbon steels and stainless, is the complete lack of carbides in these particular carbon steels. This means the carbon steels will abrade (grind) much more easily than stainless, because the chromium carbides (and/or vanadium carbides) in the stainless are much harder. On diamond hones especially, simple carbon steel like 1095 or CV can feel almost buttery-soft when grinding it. That's due to the lack of carbides in these steels. Additionally, a combination of relatively high chromium and relatively low carbon in the simpler stainless steels (like 420HC) will usually tend to make these steels more ductile, which translates to burrs & wires that are more stubborn to remove (they bend a lot, but are more difficult to break off). The slightly better stainless, with a little more carbon in relation to the chromium (12C27, AUS-8) are usually a little easier to deal with, in terms of cleaning up the burrs. And with 420HC, a small increase in RC hardness can also make it easier to remove the burrs (they become brittle enough to break away more easily). Best example for this is to compare Case's 'Tru-Sharp' stainless (420HC) with Buck's slightly harder version of the same steel. Case heat-treats theirs to ~55 HRC, give or take, and Buck does it at ~57-58 HRC. The difference that I most often see between these two is, the burrs clean up much more easily on Buck's blades. In terms of edge-holding, I don't have any complaints about either of them, with the additional qualifier that it's important to make sure the ductile burrs/wires are completely cleaned up on the Case blades. If not, the burrs/wires tend to fold over in use, and make the edge seem to 'dull' quicker.
Any of the stainless steels you listed are very easy to sharpen, using something like silicon carbide (either stones or wet/dry sandpaper, which is my favorite for these). These are all what I'd call 'middle of the road' stainless steels, with the 12C27 and AUS-8 probably in the upper half of that mix (higher carbon content). In particular, Sandvik's steel (12C27) is manufactured with a very pure process, which produces very fine grain and therefore finer edges (think of Opinel's or Mora's stainless blades).
In stropping, the 1095 and CV respond GREATLY to green compound, followed by bare leather. Also works pretty well with the lower-carbon stainless like 420HC. The slightly higher abrasion-resistance of stainless with a little more carbon seems to respond well to stropping with aluminum oxide or silicon carbide compounds.
David
