Even “better” blade steels?

[OrangeBlueOrangeBlue]

That is exactly the point. If the abrasive is larger than the carbides it will remove the steel and the carbide. Which is what is happening at 400-500grit and coarser. Those are larger abrasives that are just ripping everything out of the edge. That is fine for setting your bevel which is exactly what I said earlier. You can absolutely use Alum oxide, SIC, or ceramics at 4-500 grit. However, once you get higher than that grit, the abrasives that you are using are now going to just be ripping out carbides.

If you are getting fine results with Maxamet, thats fine good on you and dont change the way you maintain your blades if you are getting good results. That being said, there has been a lot of writing substantiating carbide tear out in high vanadium steel at higher grits both here on the forums from people actually making these abrasives like FourtyTwoBlades over at Baryonyx and Larrin Thomas.

https://www.bladeforums.com/threads/carbide-tear-out-questions.1610190/#post-18392924
FortyTwoBlades on Carbide Tearout: "It's something that seemingly can occur in some rare circumstances, but is extremely unlikely in most of the situations it's commonly thought to occur in."

The only evidence of carbide tearout I've found, from Larrin or anyone else, is with large carbides in ingot steels. A good example is the comparison Larrin has posted a few times between 154CM and CPM-154, where there are large voids (around 4 micron) in the edge of the 154CM sample, which aren't present in the PM version with its smaller carbides.

I would expect that with finer soft abrasives you would see the steel "eroding" around the carbides, like in Todd's photo, and once the carbide is exposed enough then it would "tear out". I would expect the real limit here is just how fine of an edge you can get this way, as in no finer than the size of the carbides. It is also a very slow way of sharpening.

I am always looking for a better steel and look forward to what develops. As for predictions, I would look to ceramics. There are already, and have been for some time, some very interesting ceramics used in metal cutting lathe inserts, and even some end mills. They are for cutting hard metals where tungsten carbides don't hold up.

As for it being hard to sharpen I haven't found that steel yet. Maxamet sharpens as easily as anything with the right stones.

I think the point about the fineness of the edge and the relative size of the carbides is the main issue. If you've got an ingot steel with 4-micron carbides, you can't have a 1.5-micron edge without the carbides cracking off like a burr. Using a progression of diamond or CBN abrasive that can actually cut the carbides allows you to actually incorporate the carbides into the edge bevel. But, if you've already used something softer and have the carbides bulging out of the edge, you won't be able to switch to a harder fine-grit abrasive to incorporate the carbides into the edge, they'll just crack off. PM steels have much smaller carbides, which are much more readily incorporated into a fine edge.

 

[CuttnStuff]

Enjoyable thread. I'll add my .02 with the disclaimer that I know almost nothing about steel technology...but why should that stop me? ;-)

Seems to me that the secret of better steels is controlling the blending of materials at a finer and finer level. I have to believe that nano technologies could be applied in some way to steels (or maybe related materials) at the atomic (or lower?) level. I'd bet that we will see some groundbreaking material advances in the next 20-50 years that will put current technology to shame.

 

[c7m2p3]

https://www.bladeforums.com/threads/carbide-tear-out-questions.1610190/#post-18392924
FortyTwoBlades on Carbide Tearout: "It's something that seemingly can occur in some rare circumstances, but is extremely unlikely in most of the situations it's commonly thought to occur in."

The only evidence of carbide tearout I've found, from Larrin or anyone else, is with large carbides in ingot steels. A good example is the comparison Larrin has posted a few times between 154CM and CPM-154, where there are large voids (around 4 micron) in the edge of the 154CM sample, which aren't present in the PM version with its smaller carbides.



I think the point about the fineness of the edge and the relative size of the carbides is the main issue. If you've got an ingot steel with 4-micron carbides, you can't have a 1.5-micron edge without the carbides cracking off like a burr. Using a progression of diamond or CBN abrasive that can actually cut the carbides allows you to actually incorporate the carbides into the edge bevel. But, if you've already used something softer and have the carbides bulging out of the edge, you won't be able to switch to a harder fine-grit abrasive to incorporate the carbides into the edge, they'll just crack off. PM steels have much smaller carbides, which are much more readily incorporated into a fine edge.

This is FourtyTwo in the same thread you just posted....

That's 'cause they aren't. They can abrade the steel substrate, but not the carbides themselves. They'll put some degree of wear on them, but it'll be rounding them from wear rather than shaping them by cutting. Vanadium carbide is harder than aluminum oxide by a not-insignificant margin.

Which is exactly the point and what I and others have been saying. You can use other abrasives to set the bevel and even get a pretty acceptable edge...however you are going to just be erroding away the steel substrate and not actually cutting and shaping the carbides so you are going to have them hanging out there and clinging to the edge like you showed in your maxamet picture. Im sure that edge actually will test pretty good on a held piece of paper or on a finger nail just fine but those carbides are not cleanly cut along the edge and when there is any lateral force applied to that edge, those carbides are liable to be torn out or the edge will roll because the carbides are not there to support the thin, soft substrate material around them.

Once again, im not telling you to do anything different. If that edge is fine on your maxamet for the cutting tasks that you have, dont change anything. But to say that it has been decided that you can sharpen any steel with any abrasive regardless of the carbide type or % is not where most of the community is.