nopomo
feels hard on the stones
Kind of sounds like an S-grind.
The Effect Of “Edge Aggression” Between Steels
- Thread starter Barmoley
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This test is interesting but another way to look at it is that the 440c was just sharpened better? If you look at the before and after they both lost the exact same percentage of their edge. I cant believe that 52100 at 65hrc has the exact same edge retention as 440c at 59.6??? Does that make sense to anyone else?
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I'd tend to agree. Different edges, especially different progressions. I would try to enhance each blade's properties and not fighting them. Stopping at 2k after a 500 or 800 with the 440C, and perhaps using it only for stropping and deburring. While giving a full tight progression with the 52100. Perhaps ending on a Naniwa Junpaku 8k, or a Shapton Pro 12k. Both deliver a similar degree of refinement with some bite. Don't worry, no pure polishers.
That isn't really what the test shows. In fact Shawn clearly comments on that.
"Results Testing shows despite the lower BESS sharpness and lower HRC hardness the 440C at the same edge angle, edge finish, blade curve/profile and behind the edge thickness showed less force in grams needed to initiate the slice in the tomato skin."
The test is indicating that hardness, like everything else, is just one part of a much larger equation. He's comparing two different steels to see the effects of the carbides on cut initiation. To understand the impact of the hardness in this test, you'd have to compare the same steel at different hardness ratings.
Shawn isa highly accomplished sharpener who has done this exact type of sharpening for myriad scientific tests and he used a fixed system so I trust any differences in edges would be so minimal as to not be a factor.
Exactly, what would testing at different angles accomplish? Worse yet why would anyone want to optimize edges for each steel for this particular test? This is not a test of steels and which edges or geometries are best for which steel. Can we for a second get away from "OMG, my favorite steel did worse than that other steel that I think sucks".
I also want more testing on this, but it has to be reasonable and relevant. The samples tested have to be as close to each other as possible in everything besides what is being tested, otherwise how would you know which attributes contribute to which results. Testing with different grits would be interesting, to see for example if at higher grit the differences disappear due to the smoothing of the micro structure. Can we stop fixating on 52100 vs 440C, this test could've been done with any other set of steels that have drastically different micro structure.
I understand that, what I am saying is that both steels lost exactly 60% of their initial edge cutting the same medium for the same amount of cuts.
That seems strange to me.
If we are only looking at initial bess score from the exact same sharpening sytem/time/thickness etc. I think this is a cool test to see how sharp a steel can get.
SABOL BROTHERS
KKF Supporting Craftsman
Without knowing the exact science behind "sharpness", we love K390 edges more than anything else. Super easy to sharpen to around 10-20 BESS, yet still extremely aggressive at that level of sharpness.
One can only dreamApexUltra Chevron grind please@Kippington
nopomo
feels hard on the stones
Is this a rhetorical question? You won’t know until you find out—that’s the point of experimentation.
It is not a rhetorical question. In light of what is being tested what would you expect testing at different angles would accomplish? What is your hypothesis here that you are trying to test?
nopomo
feels hard on the stones
I appreciate your sharing this with the forum (and Shawn performing and presenting the tests) and don’t mean to come off as confrontational. I am genuinely curious.
Angle would just be another thing to test after trying other grits. The hypothesis would be that the effect of microstructure on edge aggression is independent of apex angle.
Maybe the effect is even more pronounced on a 20 dps edge, maybe the difference goes away at 10 dps, but it seems premature to extrapolate based on a single set of conditions. The possibility of a synergistic effect between microstructure and finish is specifically mentioned in the paper.
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Seems unlikely, but anything is possible I suppose. If you saw anything very different it would most likely be at the extremes and I am not sure what value that would add. Given limited resources and that 15 dps is a pretty common angle for many types of knives, testing different angles wouldn't be high on my priority list.
Its used a lot in kitchen knives. Just not ones from japan
That isnt too crazy to me.
440c is a good bit more wear resistant. But it was ran at a lower hardness.
52100 is less wear resistant, but harder.
Doesnt seem too crazy to me.
I would be interested to see a high vanadium cold work tool steel at 65+ tested. And some kind of ultra hard high speed steel as well ( hap 72, zmax, maxamet type steels)
Tripe B 15V laser? Would love to try it
Funny to see all the reactions to such a simple test. By which I do not mean useless, on the contrary, I want to thank @Deadboxhero for doing it.
By simple I mean that it is only doing what it aims to do, and the premises are simple.
No need to react so much about 52100 - but no I do not think the test could have been done with just any steels. In the infancy of trying to test this, I'd tend to believe Shawn chose 52100 for its particular place as a "Carbon" steel with the chromium addition and resulting regular carbides into still a very fine structure and matrix. Could have chosen AEB-L and it would have worked about as well, but you know, the more of a difference both in composition and in resulting microstructure, the more it makes sense to me for a first test. But still 52100 stands out of the "Carbon" pack with a regular amount of carbides, and walking the fine line into a low alloy. It makes more sense than using the finest carbon steel available.
There are still good reasons to love 52100 for behaving mostly like carbon steel but having that extra bite and slight extra corrosion resistance. And more importantly, the test should change absolutely nothing to the steels you prefer and the reasons why.
All it really aims to do for now is to lay some more grounds into proving the microstructure does affect the resulting bite of an edge.
Why testing different DPS or thickness behind the edge is not so interesting is that it has already been forcibly proven that any kind of retention improves linearly with those two aspects more optimized, or decreases linearly when less optimized.
I'd think I'd like to see the same test carried with 52100 mellowed out to similar RC than the 440C. I mean, after all, @Larrin extensive catra testing does bring us sufficient pinpoint background data to see Shawn test here in its most informative light. But I think that for the same reasons, levying out RC with the same steels to the very same sharpening and geometry would help greatly into confirming some finer points vs. what we already know.
By simple I mean that it is only doing what it aims to do, and the premises are simple.
No need to react so much about 52100 - but no I do not think the test could have been done with just any steels. In the infancy of trying to test this, I'd tend to believe Shawn chose 52100 for its particular place as a "Carbon" steel with the chromium addition and resulting regular carbides into still a very fine structure and matrix. Could have chosen AEB-L and it would have worked about as well, but you know, the more of a difference both in composition and in resulting microstructure, the more it makes sense to me for a first test. But still 52100 stands out of the "Carbon" pack with a regular amount of carbides, and walking the fine line into a low alloy. It makes more sense than using the finest carbon steel available.
There are still good reasons to love 52100 for behaving mostly like carbon steel but having that extra bite and slight extra corrosion resistance. And more importantly, the test should change absolutely nothing to the steels you prefer and the reasons why.
All it really aims to do for now is to lay some more grounds into proving the microstructure does affect the resulting bite of an edge.
Why testing different DPS or thickness behind the edge is not so interesting is that it has already been forcibly proven that any kind of retention improves linearly with those two aspects more optimized, or decreases linearly when less optimized.
I'd think I'd like to see the same test carried with 52100 mellowed out to similar RC than the 440C. I mean, after all, @Larrin extensive catra testing does bring us sufficient pinpoint background data to see Shawn test here in its most informative light. But I think that for the same reasons, levying out RC with the same steels to the very same sharpening and geometry would help greatly into confirming some finer points vs. what we already know.
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At least one exists.I am still sorry I didn't buy it when I had the chance. Couldn't pull it off at the time.
SABOL BROTHERS
KKF Supporting Craftsman
Absolutely. We would love to see all the steels you mentioned tested the same way. And CPM REX 121 too.
Which one do you think would be the most aggressive?
You maker guys are in a perfect position to make this happen. The specs are known, all that is left is to make some blades out of these steels. I am sure most of us would love to see all these tested.
Sounds like something I would probably want a jig to do if i was to try that
Idk.Absolutely. We would love to see all the steels you mentioned tested the same way. And CPM REX 121 too.
If we are assuming its going to have to do with a difference in the hardness between the matrix, and the hard carbides. Then potentially the ones that would be the most aggressive, would be ones with high volumes of significantly harder carbides than the matrix.
I can't remember the carbide volumes, and types for the high speed steels, but I'm pretty sure if i remember correctly rex 121 has at least as much mc carbide as 10v, so if what I am assuming comes into play, does. Of the 70ish hrc alloys that would be the one that probably is the most agressive.
But, it could maybe just be the cold work tool steels since even at the top of their hrc range you generally arent going higher than 68. So that could put a bigger difference between them, while still by no means being a soft matrix.
Anyway, I'm talking out of my ass. I have no clue which of them would really have the most aggression.
But I might as well give my anecdotal experience and say i really like how the 10v type steels feel after sharpening.nopomo
feels hard on the stones
I’d be most curious to see a comparison between ingot and PM versions of 440C—that would reduce the number of variables and be more of an apples-to-apples situation.
SABOL BROTHERS
KKF Supporting Craftsman
What's wrong with testing and comparing different grades of steel? Why not compare plain carbon steels, stainless steels, cold work tool steels and high speed steels under the same test conditions and see which steel is the best and most aggressive cutter/slicer?
Cast vs PM are quite different end products and would essentially be a separate, and maybe not as demonstrative, test. The PM version likely has much smaller carbides. The carbides are the important factor here.
When cpm-d2 became available years back everyone got excited about it, but then there were ramblings that it didn’t cut as aggressively as regular d2. Of course this was for very few examples without any real testing or any standardization on tests or methodology, so pretty useless really.
Yeah. I was thinking 1075 with a careful heat treatment to dissolve all non tempering carbides would be also interesting to see tested
Thats their point I believe.
That basically the composition would be the same. They could be heat treated to the same hardness easily, and the only variable left would be carbide size.
Or 154cm, vs cpm 154 would be interesting also.
But also, doing d2, psf27, and cpm d2 could be really interesting to see. Since the carbides would be increasingly fine, and more evenly distributed in each.
But the test is about edge aggression. If the PM version has smaller carbides and thus is more like the 52100 then you're no longer testing the carbides and their impact on cutting ability.
Even pm d2, isn't going to have carbides as small as something like 52100
Also. I dont see how we wouldnt be testing this. In the same steel, with the only difference being their carbide size. Same geometry, and hardness. Doing this same test. Quite literally the only thing we would be testing is carbides and their effect on cutting ability. Specifically if carbide size in a steel with all else being equal has a measurable effect.
Yeah as a verification test it makes sense. I mean, if you had the money, time and inclination you can setup a full DOE and get real sciencey.
