Larrin
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Photo micrographs of various steels, and two worn knife edges, one from 440C and one from 13C26: http://www.fototime.com/inv/00BD612B8194CE6
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Photo micrographs
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fitzo
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Interesting micrographs, to be sure. Thanks for sharing them, Larrin. It's great to see stuff like this.
Is the data set generated under what I would refer to as "scientifically rigorous" conditions? By that, I mean are they all generated out of the same laboratory under controlled conditions to optimize results for each sample?
Are we looking at the "best" each steel can be?
Thanks.
Is the data set generated under what I would refer to as "scientifically rigorous" conditions? By that, I mean are they all generated out of the same laboratory under controlled conditions to optimize results for each sample?
Are we looking at the "best" each steel can be?
Thanks.
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- Oct 18, 2001
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....smaller grain structure, it would seem.
I see it's on Admiral's site now....around $16/lb in the size I want. Not bad...
Definitely going to get a few bars to play around with.
I see it's on Admiral's site now....around $16/lb in the size I want. Not bad...
Definitely going to get a few bars to play around with.
Larrin
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They were all done by the same labratory in Sweden, these were taken by Sandvik. I didn't ask them directly but the feeling I got from talking to them was that they took the first sample that they photgraphed. I don't think they tried to find the largest carbides in competing steels and the smallest from theirs. D2, for example, has super large carbides everywhere, and 13C26 doesn't have any large ones.
My analysis is that the size of the carbides in 13C26 is of course a tiny fraction of the size of the others, which I like for thin edges. I was surprised by the microstructure of 440C, it is surprisingly fine, though wouldn't be mistaken for a PM steel, of course. 19C27 is a pretty fine structure, it looks pretty good for a conventional cast steel. And though theoretically S30V should have finer carbides than CPM-154, I was still surprised by the dramatic difference in the carbide structure of the two. If S30V wasn't difficult to finish and sharpen, I would be very interested in it for hunting knives or others that perform mostly slicing cuts. It was also interesting to see how much different 154CM and ATS-34 look, I wonder if they consistently look that different or if they generally look the same, my feeling is actually the former.
A super thin edge is like half a micron, and a dull one is 10-12 microns, using that information, you can see that a steel like 13C26, with an average carbide size of about half a micron and the largest just over one micron would be very good at holding those initial sharp edges, but once you get down to the average size of a the CPM-154 carbides (about 4-6 microns), the CPM-154 would start to hold its edge longer due to more wear resistance. The larger the geometry, the more the large carbides are beneficial to edge retention. Of course, the fine carbides would still mean that the 13C26 is radically tougher and much easier to sharpen. And a monster 50 micron carbide from D2 would be completely useless in an edge, it would just fall out.
My analysis is that the size of the carbides in 13C26 is of course a tiny fraction of the size of the others, which I like for thin edges. I was surprised by the microstructure of 440C, it is surprisingly fine, though wouldn't be mistaken for a PM steel, of course. 19C27 is a pretty fine structure, it looks pretty good for a conventional cast steel. And though theoretically S30V should have finer carbides than CPM-154, I was still surprised by the dramatic difference in the carbide structure of the two. If S30V wasn't difficult to finish and sharpen, I would be very interested in it for hunting knives or others that perform mostly slicing cuts. It was also interesting to see how much different 154CM and ATS-34 look, I wonder if they consistently look that different or if they generally look the same, my feeling is actually the former.
A super thin edge is like half a micron, and a dull one is 10-12 microns, using that information, you can see that a steel like 13C26, with an average carbide size of about half a micron and the largest just over one micron would be very good at holding those initial sharp edges, but once you get down to the average size of a the CPM-154 carbides (about 4-6 microns), the CPM-154 would start to hold its edge longer due to more wear resistance. The larger the geometry, the more the large carbides are beneficial to edge retention. Of course, the fine carbides would still mean that the 13C26 is radically tougher and much easier to sharpen. And a monster 50 micron carbide from D2 would be completely useless in an edge, it would just fall out.