what steels and why

[Larrin]

Hmmm.... kind of casually mentions it in passing. In the context of polishing a flat surface, not really the same as a knife edge.

Also, the context I have always read is the "large" carbides pulling out of the knife edge is the pull out is noticeable. How big is a "large" carbide? I still have my doubts.

What I'd like to see is some photomicrographs of a knife edge showing the missing carbides. Actually, I would love to see ANY photomicrographs of some knife edges, especially a transverse view. Are you aware of any Larrin?

Thanks,

-AJ

Since edges are two flat surfaces that meet, I don't see it as being unrelated. Obviously it is a phenomena that is observed.

A large carbide is of course as difficult to define as any other "large" thing. 20 micron+ carbides could probably be classified as large carbides. You're unlikely to notice individual missing carbides, the effect is noticed because carbides tend to cluster, and steels with large carbides tend to also have lots of carbides. You of course wouldn't be likely to observe carbide pullout without going to a fairly polished sharpening.

Here's the first micrograph I could find in my collection. I'll let you come up with your own analysis:

Uploaded with ImageShack.us

[Larrin]

Here's a picture of some ugly carbides in D2:

Uploaded with ImageShack.us

[ajhuff]

Thanks!

-AJ

[Larrin]

More micrographs! I hope everyone can't get enough of them. Here is showing how carbides effect the radius of an edge with cutting:

[DevinT]

Hmmm.... kind of casually mentions it in passing. In the context of polishing a flat surface, not really the same as a knife edge.

Also, the context I have always read is the "large" carbides pulling out of the knife edge is the pull out is noticeable. How big is a "large" carbide? I still have my doubts.

What I'd like to see is some photomicrographs of a knife edge showing the missing carbides. Actually, I would love to see ANY photomicrographs of some knife edges, especially a transverse view. Are you aware of any Larrin?

Thanks,

-AJ

If you are an avid knife user, you will notice after some use a knife will have some micro chipping which is carbide pull out, at the very least micro cracking that propagates from the carbides at the edge.

This is something that John Verhoeven ( former head of metalurgy at Iowa state) talks about.

Run your knife off the end of your thumbnail and you will get some feed back. Lastly, it's not wise to argue with Larrin.

Look at an edge under magnification and see what you learn.

Hoss

[ajhuff]

I was only asking questions not arguing. I greatly appreciate the feedback from Larrin.

-Aj

[DevinT]

More micrographs! I hope everyone can't get enough of them. Here is showing how carbides effect the radius of an edge with cutting:

This top photo is of 12c27 and the bottom photo is of 440-C. Ofcourse the 12c27 has better edge stablility.

Hoss

[SpikeC]

I'm loving this stuff! Great images of what is actually going on.

[Eamon Burke]

These are so cool! Thanks Larrin!

[MadMel]

Classic example of a picture speaks a thousand words! Those pics made it much easier to understand!