Large Carbide Steel and sharpness?

[Incahiker]

Ok guys, I'm gonna ask you steel gurus a question to clear up my thoughts.

First, we always hear people talk about fine grained steel being able to take on a razor edge, such as 1095 or the sandvik stuff for stainless. From what I understand it is because these steels can have an astonishingly thin edge. Sandvik carbides are .5 microns, thus super sharp edge.

Then everyone talks about S30V which have larger carbides. And if you sharpen the edge thinner then the carbide size then basically the carbide will fall out while you sharpen it or it will fall out while you use it and leave an unsharp edge.

But, what about when you sharpen the carbides with something that is harder then the carbides, such as diamond. Lets say you sharpen the edge of S30V with a diamond paste at .25 carbides, then they carbides are also sharpened equally with the rest of the material in the steel and thus all elements take on this really fine .25 micron edge, better then the .5 sandvik edge.

Now the question is, will the S30V hold the edge longer then the sandvik steel, or will the sandvik still have better edge stability? I hope I explained everything clearly for this question to be answered properly, lol.

 

[sunshadow]

The carbides are not well anchored, they tend to crack and fall out rather than abrade leaving large jagged recesses in your edge

look for the CPM versions which have extremely fine carbides because of the powder metallurgy process (I personally plan on using CPM 154 CM for the best of both worlds)

-Page

 

[mete]

You are confusing 'grain size' and 'carbide size' ! It's best to have both small .
Large grain size from poor HT will make for a brittle steel and one that won't take a really good edge. Small carbides make for a better edge and one that holds up to wear better .
Compare 154CM and CPM154. The CPM version has smaller more evenly dispersed carbides that takes and holds a very nice edge.My favorite !!

 

[Incahiker]

The carbides are not well anchored, they tend to crack and fall out rather than abrade leaving large jagged recesses in your edge

look for the CPM versions which have extremely fine carbides because of the powder metallurgy process (I personally plan on using CPM 154 CM for the best of both worlds)

-Page

Ok, so even though the cabides sharpened as sharp as 1095 or sandvik steel can get they do not hold an edge as long because these carbides crack and fall out, makes sense.

From what I have seen S30V has a pretty small grain structure compared to the rest of the stainless steel I have seen pictures of. Is the CPM 154 even finer? How about CMP-D2, how fine is this?

 

[Incahiker]

You are confusing 'grain size' and 'carbide size' ! It's best to have both small .
Large grain size from poor HT will make for a brittle steel and one that won't take a really good edge. Small carbides make for a better edge and one that holds up to wear better .
Compare 154CM and CPM154. The CPM version has smaller more evenly dispersed carbides that takes and holds a very nice edge.My favorite !!

Thanks, I am trying to understand everything correctly. Lets take this picture of D2 for example

Those huge white chunks are the large carbides D2 has, correct? Are the smaller particles the grain size? So 1095 would pretty much have none of those white carbides since its pretty much just carbon mixed with iron and a little of something else?

Here is Sandvik 13C26 for comparison, very fine with no chunks of anything, lol.

 

[Stacy E. Apelt - Bladesmith]

Consider concrete the steel. The rocks are the hard carbide. If you grind the concrete edge to a fine corner, the rocks will pop out. If the same concrete has only pea gravel, or just sand, the edge will survive better.

 

[mete]

Grains are not particles !