fulloflead said:
That is, unless you're trying to go without sharpening for a year...
In general, you would have to have really low tolerances for sharpness to even last more than a month, assuming you use the knife significantly. I sharpen kitchen knives when they start to slide at all on tomatoes or won't push right down into potatos without resistance. The easier they cut the faster and safer it is to use them. I don't usually sharpen any less with better steels, I just run more acute profiles and maintain a higher level of sharpness. The really high end blades I have rarely go below shaving and almost never below paper slicing unless I was doing something really abrasive like peeling a lot of fresh vegetables (local garden, they are not washed and thus it is similar to digging).
HoB said:
But isn't that graph deformation (deflection) and not shock (impact toughness)?
Yes, it shows both strength and ductility and both are higher. I am researching impact toughness now, torsional, charpy and izod, notched and unnotched for various steels. Some steels are notch sensitive some are not thus you can have different rankings, then there is torsional vs charpy/izod and parallel/perpendicular grain (not for torsional).
Since we are at it: how does 5160 compare to those steels in terms of toughness?
Much tougher for a vew reasons (lathe vs plate martensite and lack of heavy primary carbides), the data on carbon and alloy steels isn't as exhaustive as it is for tools steels for which there are many reference books. In regards to impacts, O1 can be spring drawn on the spine and bainited far easier than A2, thus a differential O1 blade can be tougher than an A2 full hard blade, though A2 should have better edge stability.
Razorback, assuming you were just hitting the flat with the steel layed on the anvil, you eliminated one of the major sources of impact strains which is the torque. I can take the piece of the Green Beret for example and lay it flat on a concrete step and hit it with the poll of a fiskars axe hard enough so that the step shatters under the blade, but the blade itself is fine (lost it on the sixth hit as it buried itself in a drift, I'll find it in the spring I'd imagine). Were your D2 and O1 blades shattering readily under similar impacts? Try locking the blades in a fixture and perform a charpy/izod style impact and sharpening the blades and impacting them off of something hard and checking for extent of deformation/fracture.
-Cliff
