Cliff Stamp
BANNED
- Joined
- Oct 5, 1998
- Messages
- 17,562
Carbides enhance wear resistance by becoming inherently harder (carbides can form of different crystal structure even out of the same alloys) and by become finer dispersed through the material.
However carbides themselves don't add to any cutting ability as they are too small, typically you are talking about something the size of 1-10 microns (one being very fine like 52100 and ten being coarse like D2), and even very fine abrasive like a fine India stone is > 50 micron. If you leave the edge with a really coarse finish, the abrasive size is so large that it masks any carbide structure of the steel.
The easiest way to think about this is to look at the flats of the blade. Some steels take a mirror polish better than others, however if you scratch them up badly with a coarse hone, do they look any different, no because the scratches are way bigger than any carbides.
Boyes knives cut well because of the geometry which is finer than the *vast* majority of knives (though this is starting to become less of an issue with many production knives being as finely ground) and he was among the first to promote coarser edges (and again this is now more well known).
I have used several of his knives and they don't maintain a more aggressive finish at high polishes due to the carbide structure, it is trivial to make a 52100 blade outslice them for example by leaving it with a rougher grit.
The only real effect of have seen which is carbide related in regards to aggression is a "self-sharpening" effect I have seen with heavy use. With coarse grained steels the edge will chip / tear out and thus the sharpness increases after awhile as the edge breaks into a saw where a finer ground edge will just wear smooth.
This is interesting but not personally useful as by the time the blade starts doing that, it is well past the point where I would have long sharpened it (<<25% of optimal sharpness).
Note as well that if the carbides were so large that they stuck out from the edge (like a fraction of a mm) and made a saw, they would just all crack off as soon as they were used as carbide is *way* fragile unless well supported by the steel matrix so only the surface is exposed.
However carbides themselves don't add to any cutting ability as they are too small, typically you are talking about something the size of 1-10 microns (one being very fine like 52100 and ten being coarse like D2), and even very fine abrasive like a fine India stone is > 50 micron. If you leave the edge with a really coarse finish, the abrasive size is so large that it masks any carbide structure of the steel.
The easiest way to think about this is to look at the flats of the blade. Some steels take a mirror polish better than others, however if you scratch them up badly with a coarse hone, do they look any different, no because the scratches are way bigger than any carbides.
Boyes knives cut well because of the geometry which is finer than the *vast* majority of knives (though this is starting to become less of an issue with many production knives being as finely ground) and he was among the first to promote coarser edges (and again this is now more well known).
I have used several of his knives and they don't maintain a more aggressive finish at high polishes due to the carbide structure, it is trivial to make a 52100 blade outslice them for example by leaving it with a rougher grit.
The only real effect of have seen which is carbide related in regards to aggression is a "self-sharpening" effect I have seen with heavy use. With coarse grained steels the edge will chip / tear out and thus the sharpness increases after awhile as the edge breaks into a saw where a finer ground edge will just wear smooth.
This is interesting but not personally useful as by the time the blade starts doing that, it is well past the point where I would have long sharpened it (<<25% of optimal sharpness).
Note as well that if the carbides were so large that they stuck out from the edge (like a fraction of a mm) and made a saw, they would just all crack off as soon as they were used as carbide is *way* fragile unless well supported by the steel matrix so only the surface is exposed.
