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Sandvik Hardening Guide
- Thread starter Razorsharp244
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I love fine grained high&easy obtainable sharpness 12C27's bad self, too.
Would you get kicked out if you were caught using some sweet thinly ground 10V or S90V?
The more I think about it, the more I think it would be defined by a test, just like hardness and toughness is. It would be nice to have a new "property" so applicable to knifedom.
Would you get kicked out if you were caught using some sweet thinly ground 10V or S90V?
The more I think about it, the more I think it would be defined by a test, just like hardness and toughness is. It would be nice to have a new "property" so applicable to knifedom.
Larrin
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You can grind 10V or S90V thin, though it's best if you slice with it and don't sharpen over 1000 grit.
By the way, the Sandvik club is going well, but Thom and I are the only contributing members so far, is there any way to get e-mail alerts in the social groups?
By the way, the Sandvik club is going well, but Thom and I are the only contributing members so far, is there any way to get e-mail alerts in the social groups?
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But it will get "razor" sharp if you take the time!
It may not get quite as sharp as some inc. 12C27, but it can be taken to a polished edge - it just takes some time and effort. Here's some Phil Wilson 10V and some helle stainless (12C27?). You can kinda tell the 12C27 is a bit sharper.
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The Helle had less paper moving on either side during the cutting, but the Wilson looked better doing it.
If my memory isn't warped, Steve Elliot places polished edges on high-carbide planer blades using diamond slurry on cast iron lapping plates. Apparently, most of the waterstones we know or want to know (but can't justify the expense) won't sharpen some steels past a certain level, but the diamond abrasives will. I wonder if boron carbide would be an equalizer in such instances. Brent Beach hasn't met a steel that doesn't bow to his use of lapping film, either, so maybe something else is involved.
If my memory isn't warped, Steve Elliot places polished edges on high-carbide planer blades using diamond slurry on cast iron lapping plates. Apparently, most of the waterstones we know or want to know (but can't justify the expense) won't sharpen some steels past a certain level, but the diamond abrasives will. I wonder if boron carbide would be an equalizer in such instances. Brent Beach hasn't met a steel that doesn't bow to his use of lapping film, either, so maybe something else is involved.
Someone better tell him he cann't do that. It doesn't fit the stability carbide theory.
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Neither did Beach's getting more chipping with A2 planers than D2 planers, but it wasn't the case with all A2 and the M2 planers still pwned everything else.
You and Broos are humbly invited.
If you'd like, I can set an edge of about 10° per side on one of your D2 knives and do the same with one of your 13C26 or 12C27 folders and put a high polish on both blades. Got the silicon carbide up to 5μ and diamond at 0.5μ
You and Broos are humbly invited.
If you'd like, I can set an edge of about 10° per side on one of your D2 knives and do the same with one of your 13C26 or 12C27 folders and put a high polish on both blades. Got the silicon carbide up to 5μ and diamond at 0.5μ
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Yo, db! Been wanting to comment on this, but having Adult Attention Deficit Disorder ... uh ... what was I going to say?
Oh, yeah ...What sold me on the "carbide theory" we're talking about here was examining edges under magnification (300x plus) when I got wrapped up in doing edge retention testing a while back. Not only was I looking at edges at different stages of wear or degradation during testing, but also during sharpening. Interestingly, what really caused me to take notice was how differently my Sandvik blades were behaving, even compared to some carbon steel blades.
And BTW, something I don't think I've ever mentioned, or seen mentioned, is that you see a lot of different behavior with edges when examining at this level of magnification, and different high alloy stainless steels can show very different types of edge degradation, even though what you see would generally be described as chipping or microchipping. VG-10, S30V and N690, for example, show very different patterns of edge degradation in use on identical materials, which IMO clearly indicates very different structural properties. But they all show chipping at the edge, as opposed to the smooth, even wear you see on 12C27 or A2, for example.
In my mind this all relates to "edge stability" even though I can't offer you a good definition of the term. But I think edge stability is one of those things you know it when you see it. To me it's most readily recognizable when trying to find optimum angles, especially where a fairly fine, polished edge is desired: steels with lesser edge stability will rapidly lose sharpness due to this microchipping when compared to steels with greater edge stability when performing a specific type of cutting work. I believe there are numerous factors that affect this property, and generalizations are difficult ... for example, SG2 steel in my experience performs much better at lower edge angles than VG-10 or S30V. But it's also a very different alloy, at higher hardness.
Even though edge stability may be hard to define and quantify to everyone's liking, I still think it's a very useful concept. Edge stability is what steels like 13C26 and 12C27 have that makes them perform as well as they do, IMO. Steels like S30V, on the other hand, rely on other things such as wear resistance to achieve their performance characteristics.
Larrin
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That's very fascinating DOW, it's often discouraging when very vocal knife users will adamantly oppose edge stability, or the effect of carbide size, without any type of sharpness testing or microscopy. Feel, especially with inexperienced users, rarely tells much.
Thanks Thom and your offer is very tempting. Most of my ugly uneven hand ground convex edges are pretty darn close to 10 to 15 degrees per side now, but only finished to a sloppy 4000 to 8000 finish if I wasn't real lazy sharpening em..
I agree. Grain size hardness, edge type, angle, finish, type of cutting, and what is cut are just a few and in my opinion one isn't more important than another. Unlike some others who seem to post about carbide size and volume like it is the only thing that matters. I as inexperienced as I am don't see the theory is much of a factor with the tipical knife edge found on edc knives folders, and fixed.
Truthfully I do think it should be at least loosely defined to be a useful concept. To me it seems to really have become a buz phrase to explain way to many general things, concepts theories, and present them as facts. Thanks for commenting your post is very insightful, and I do agree with alot of it.
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Maybe it would be useful if we had an agreed-upon definition of edge stability? I'm thinking something along these lines:
Edge stability: the ability of a blade, or the inherent ability of a cutlery steel, to be first sharpened to a fine edge, with the edge angle being a factor, and to resist chipping, fracture or other degradation due to force but not from wear, when used for cutting common materials for which a knife is an appropriate tool.
Suggestions for clarifications, changes or elaborations welcome. Once we agree on something, maybe we can draw upon Thom's considerable written skills to put it all together.
Edge stability: the ability of a blade, or the inherent ability of a cutlery steel, to be first sharpened to a fine edge, with the edge angle being a factor, and to resist chipping, fracture or other degradation due to force but not from wear, when used for cutting common materials for which a knife is an appropriate tool.
Suggestions for clarifications, changes or elaborations welcome. Once we agree on something, maybe we can draw upon Thom's considerable written skills to put it all together.
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Interesting comments, DOW.
It seems there is good general guidelines of what causes it (grain size, carbide volume and size), but I suspect there may be some exceptions to these general rules (maybe FFD2 would have very high ES with larger than expected carbon volume?). I seem to recall Landes' tested it by placing a lateral load on a razor edge, then (I assume) the edges were observed and rated (?). I understand the concept, but to be honest, whenever it is mentioned I try to look up the steel's grain size, carbide volume, and carbide size (often to my frustration), so I get more out of a discussion about grain size, carbide volume, & carbide size than I can about discussing ES. It would be interesting to see those properties listed alongside a ranking of edge stability.
It seems there is good general guidelines of what causes it (grain size, carbide volume and size), but I suspect there may be some exceptions to these general rules (maybe FFD2 would have very high ES with larger than expected carbon volume?). I seem to recall Landes' tested it by placing a lateral load on a razor edge, then (I assume) the edges were observed and rated (?). I understand the concept, but to be honest, whenever it is mentioned I try to look up the steel's grain size, carbide volume, and carbide size (often to my frustration), so I get more out of a discussion about grain size, carbide volume, & carbide size than I can about discussing ES. It would be interesting to see those properties listed alongside a ranking of edge stability.
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I think per Broos' reference to Landes perhaps the nature of the force needs to be qualified more. It sounds like a steady or slowly applied force is used as opposed to an impact force, which would measure toughness.
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The type of angle, the amount and type of force (i.e. gradual or shock, the direction of blade travel to determine the amount of shearing...), the crystalline structure (i.e. which types of martensite, austenite, pearlite, or bainite are in the blade and in which percentages. Related, how much carbon is at grain boundaries?) the media being cut, the size and direction of the furroughs (or their lack) in the edge - these all need to be quantified.
Assuming HRC58 and a task of chopping pitchwood, I'd venture that 154CM or D2 that's 0.03" thick 0.1" above the cutting edge has greater stability than 12C27 that's 0.01" thick 0.1" above the cutting edge. In a chef knife chopping fennel in a traditional down and forward shearing style, my guess is the 12C27 would last longer, but would that be a higher level of stability or from inducing a lower level of fatigue? And who eats so much fennel that fatigue would be an issue?
Assuming HRC58 and a task of chopping pitchwood, I'd venture that 154CM or D2 that's 0.03" thick 0.1" above the cutting edge has greater stability than 12C27 that's 0.01" thick 0.1" above the cutting edge. In a chef knife chopping fennel in a traditional down and forward shearing style, my guess is the 12C27 would last longer, but would that be a higher level of stability or from inducing a lower level of fatigue? And who eats so much fennel that fatigue would be an issue?
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Just trying to put together the definition I did (which nearly gave me a headache, and new appreciation for those working for Merriam-Webster) I think gave me new appreciation for the complexity involved.
IMO edge stability is an important enough characteristic that we all need to be aware of it, and it needs to be discussed sometimes. I'm pretty comfortable with a general, non-quantified definition ... as is the case with edge retention, I think in very relative terms anyway, e.g. "Blade A remained sharper than blade B after X cuts, measuring sharpness by pushcutting newspaper." Dr. Stamp might have the ability and determination to try to quantify it, but I don't ... and besides, just look at the fate that befell him!
IMO edge stability is an important enough characteristic that we all need to be aware of it, and it needs to be discussed sometimes. I'm pretty comfortable with a general, non-quantified definition ... as is the case with edge retention, I think in very relative terms anyway, e.g. "Blade A remained sharper than blade B after X cuts, measuring sharpness by pushcutting newspaper." Dr. Stamp might have the ability and determination to try to quantify it, but I don't ... and besides, just look at the fate that befell him!
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Hi Jerker!
Would 7C27Mo2 hardened to RC55-57 be noticeably more impact resistant than 12C27 at a similar range of hardness? This would be for a large brush-clearing knife which may occasionally strike rocks.
Many thanks,
Thom
Would 7C27Mo2 hardened to RC55-57 be noticeably more impact resistant than 12C27 at a similar range of hardness? This would be for a large brush-clearing knife which may occasionally strike rocks.
Many thanks,
Thom