James - good input! It looks like Elmax does reasonably well with edge retention (by Ankerson's tests) as long as it is HT to > 60 rockwell. Mike Stewart also noted elsewhere that Elmax edge retention is much improved over 60 and not as good under. What is your strategy with Elmax to optimize its edge retention / toughness ?
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S30V vs M390 Toughness?
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James - good input! It looks like Elmax does reasonably well with edge retention (by Ankerson's tests) as long as it is HT to > 60 rockwell. Mike Stewart also noted elsewhere that Elmax edge retention is much improved over 60 and not as good under. What is your strategy with Elmax to optimize its edge retention / toughness ?
bodog
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What a great thread about great all around steels and what to consider when choosing knives. Cutting cardboard or rope for hours may say something, but it's only part of the equation for real world knives. Thank you guys for the input.
Is the general consensus that you can't really go wrong with elmax for just about any knife application? It's where it seems like it's leading to.
Is the general consensus that you can't really go wrong with elmax for just about any knife application? It's where it seems like it's leading to.
Ankerson
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I don't think ELMAX is a bad choice at all, that or M390 have a very broad range of uses.
james terrio
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In a nutshell, knives whose edges chip or tips break when used to cut/chop/dig through resilient materials like wood (including knots) and golf balls aggressively. I realize that's not terribly "scientifical", but it's what matters to my clients.
Extremely tough! This is a function of the structure within the steel itself (lath martensite rather than the plate martensite that's typically formed in steels with more than .8% carbon), and the fact that they are basically 99% iron. Unfortunately, they generally don't hold an edge very well in comparison to alloys with more carbon and carbide-forming elements. Which is not to say they can't be made into good knives, of course; lots of people are very happy with blades made of simple steels like 1084, S7, 5160, etc.
Warning: blatant self-promotion ahead
You may find these reviews and thoughts regarding my Fugitive prototype in Elmax interesting. It was beat on pretty dang hard and held up very well. That's one example of actual fact of a high-carbide-content knife being what I consider "tough".
My current batch is being HT'ed at 60Rc. We'll see how it goes
That's my opinion so far, yes. Whether or not it will stand up to the pressures/leverage induced when chopping aggressively with an 8" or 10" blade remains to be seen, but I'm reasonably confident it will hold up just fine. The only problem I have with Elmax (and CTS-XHP for that matter) is that it's hard to find in barstock appropriate for knife blades :grumpy:
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I have a few clients too, and drawing on some practical experience, I have made hundreds of knives in S30V, a great many of which have gone into very hard use environments without a single failure. I know Strider and others have done the same with many hundreds or even thousands more. This isn't just about the name on the steel or numbers on the page. It's about all the details of the knife being designed and made to suit the intended purpose. This isn't exactly a Chinese restaurant where you can pick one from Column A (any use), one from Column B (any steel) and another from Column C (any design), put them together and get a satisfying result. They all get mixed together and it's the combination that decides if it works.
chiral.grolim
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{regarding spring-steel knives}
Extremely tough! This is a function of the structure within the steel itself (lath martensite rather than the plate martensite that's typically formed in steels with more than .8% carbon), and the fact that they are basically 99% iron. Unfortunately, they generally don't hold an edge very well in comparison to alloys with more carbon and carbide-forming elements. Which is not to say they can't be made into good knives, of course; lots of people are very happy with blades made of simple steels like 1084, S7, 5160, etc.
...{regarding Elmax knvies}...
My current batch is being HT'ed at 60Rc. We'll see how it goes
I am not a metallurgist, and sure James has already read this, and it was posted earlier in the thread, but here it is again: http://www.kau.se/sites/default/files/Dokument/subpage/2010/02/26_349_359_pdf_19432.pdf
According to this publication, M390 achieves its highest toughness level (approximately that of O1 tool steel) at a low temper and hardness ~60 Rc, but then tapers off as tempering temp increases until it gets a boost again at high hardness when RA is mostly all converted, Rc >60.
Elmax achieves a substantial boost in toughness in the high-temper range, achieving at 64 Rc toughness around or better than O1 achieves at 58 Rc.
Perhaps James could kick up the hardness a little? *shrug*S7 tool steel is a cut above even 5160 & L6 in toughness, those are roughly equivalent to CPM-3V but with much lower wear-resistance. 1095 is closer to O1, i.e. on level with Elmax and M390 is the latter have the proper HT for such toughness. It'd be interesting to see if Crucible is able to achieve similar performance with their CPM-20CV as they currently list it as only on par with 440C, or perhaps their data is more reliable than we're getting out of the EU
In any case, that is standardized impact-testing, not testing knife blades, but it is encouraging for makers looking to push the envelope. Welcome to 2014 indeed!
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chiral.grolim
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To Jerry regarding CPM-3V chips, I'm trying to find a better photo of the blade before I restored it, but here is a crappy one of that GSO-10 edge after hitting the "tree staple" (keep in mind that the staple had been work-hardened by the guy who hammered it deep into the pine tree he was using as a fence-post for his barbed-wire):
You can see the damage somewhat better in this video, bet at ~5:20:
[video=youtube;IZe4T50nrog]http://www.youtube.com/watch?v=IZe4T50nrog[/video]
You can see the damage somewhat better in this video, bet at ~5:20:
[video=youtube;IZe4T50nrog]http://www.youtube.com/watch?v=IZe4T50nrog[/video]
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That greatly surprises me because it should have deformed more, even if it also chipped. I've seen similar degrees of damage in a 3V edge when striking something very hard, but always as deformation and never a chip. Might be a different heat treating schedule than Bos uses. Hard to say. I doubt the staple work hardened much; it's mild steel. Even so, mild steel can be troublesome to lower hardnesses. I've tried repeatedly to put an edge on an Ontario machete, 1095 at Rc52/53, that could cut a common nail, but the nail wins everytime. The same edge however will chop wood all day with only minor issues, especially if it's green wood.
Edited to add, what is with all the pitting in that blade? Did it rust? If so, rust might explain the edge damage.
Further Edited: I should have watched the video before commenting. Two things. For one, it's not clear from the video that the damage is a chip or deformation. As you look edge on you can see what looks like deformed steel pushed down into the notch. As for the rust, you'll not easily get those spots out short of serious steel removal. The rust spots are the result of contamination in the steel from the factory, a residue of slag that isn't easily removed from the melt as it is with most steels. At minimum, I etch my 3V blades to passivate the surface and remove most of that. Some I DLC coat and have done more of that lately. Clearly this vulnerability is a weakness in an otherwise excellent steel, because when it rusts, it rusts ugly. That said, it's been my experience that a light coat of good gun oil, preferably one containing teflon will usually prevent this, unless you allow the blade to remain wet for an extended period of time.
Edited to add, what is with all the pitting in that blade? Did it rust? If so, rust might explain the edge damage.
Further Edited: I should have watched the video before commenting. Two things. For one, it's not clear from the video that the damage is a chip or deformation. As you look edge on you can see what looks like deformed steel pushed down into the notch. As for the rust, you'll not easily get those spots out short of serious steel removal. The rust spots are the result of contamination in the steel from the factory, a residue of slag that isn't easily removed from the melt as it is with most steels. At minimum, I etch my 3V blades to passivate the surface and remove most of that. Some I DLC coat and have done more of that lately. Clearly this vulnerability is a weakness in an otherwise excellent steel, because when it rusts, it rusts ugly. That said, it's been my experience that a light coat of good gun oil, preferably one containing teflon will usually prevent this, unless you allow the blade to remain wet for an extended period of time.
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I appreciate your input on this thread Jerry! Not often that a knife maker of your experience and stature provides such extensive insights here. Just to be clear, I was not suggesting you could mix and match randomly - I WAS asking what stainless steel you would choose for a certain type of knife, if you were designing and implementing it (your design, your HT, etc). Reeves, Strider, and others at one time chose to use S30V and now I see a lot of S35vn from makers with reputations for "hard-use" knives. That tells me something! (That both S30V and now S35vn are considered good choices). Personally I have had poor luck with edge chipping and tip-breakage on S30V blades from reputable companies and don't bother with it anymore. It's a relative thing - those are good, perhaps there are other choices now that are better than S30V? That does not make all those knives out there suddenly poor choices, but if I have a choice about what to buy, why not buy a better solution, if there is one? (I'm not a maker, btw, I'm a consumer and have been buying and using knives for ~ 35 years).
chiral.grolim
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There is certainly deformation but that is of the thin metal left behind from the 'flake' that chipped out of the edge, similar to what is seen with making stone blades. Right at 5:20 in this video, you can kinda see it, maybe I can take another photo tonight:
[video=youtube;IpI_6BqrV80]http://www.youtube.com/watch?v=IpI_6BqrV80#t=276[/video]
The damage isn't too deep, obviously, I shudder to think what would have happened to a soft machete.
As for the rust 'freckles', they were the result of leaving the knife sheathed in my basement overnight AFTER I finished using the GSO-10 on the day i chipped the blade. I made the video for educational purposes so others knew what to expect as there wasn't a lot out there on CPM-3V corrosion at the time (all I could find were James' own photos). Since then, S!K has released their own video showing MUCH worse corrosion from extreme neglect. They do offer DLC for this model, I actually owned one but sold it, prefer the naked steel
. I'm not too worried about the freckles except on the very edge which I have since polished and removed all sign of pitting so it mustn't be very deep. I now lightly coat the blade with mineral oil before extended storage and do a better job drying after use The video does a good job catching them in the light, under normal conditions you cannot see them (per recent photo, the blemishes are hardened sap that hasn't been fully scrubbed off):
That GSO-10 blade [in post 227] looks like it has lots of microchips up and down the blade. I have a large 3V chopper that I use as a machete. It stays sharp, but microchips with repeated bushwhacking. (Peters heat treat, I think about 60 Rc). But it's much better to use than any of my simple carbon machete blades, which get dull quickly.
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There are two reasons for switching from S30V to S35VN. One is that S35VN is less prone to chipping under a wider range of circumstances, those circumstances relating to both the manufacturing process and the blade/edge geometries that can be safely used for specific purposes. There is just no question that S30V isn't very tolerant of sloppy workmanship and the makers you've named are not about being sloppy, and are extremely fussy about who heat treats their knives. Others may not be that fussy about the details. I really can't say. The other reason for switching to S35VN is that it's a whole lot easier to work with at every step in the process, and takes a nicer finish without a lot of fuss. As for your buying choices, I agree completely, choose whatever makes you feel most comfortable with your purchase. But remember, a lousy knife can be made out of the best of steels, so there is a lot more to judge than just the name of of the steel, the name on the blade matters too.
BTW, I no longer use S30V, but have gone to PSF27 which I like for a lot of reasons, after having tested to to destruction a couple times and finding it holds up remarkably well. Not quite stainless but close, much like CPM-D2. I also use CPM-154 if someone really wants stainless.
BTW, I no longer use S30V, but have gone to PSF27 which I like for a lot of reasons, after having tested to to destruction a couple times and finding it holds up remarkably well. Not quite stainless but close, much like CPM-D2. I also use CPM-154 if someone really wants stainless.
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It would be interesting to know if those production blades have been laser or waterjet cut.
chiral.grolim
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Nah, it's just a really badly pixellated image, the videos show it better - very clean except for a few spots where is cut into barbed wire or that dang spike. The damage was done in July of 2013, I haven't had issues since (been avoiding staples). Here is a video from May 2013 which is after a winter and spring of hard use collecting firewood and and fence-posts and clearing the perimeter of my property so i could install the fence. The camera pics up the paper better than my own ears, to me it was whispering through the receipt I'm cutting at ~3:20.
[video=youtube;ZvAq4H7ktSk]http://www.youtube.com/watch?v=ZvAq4H7ktSk[/video]
I want to see some images/videos of Jerry and James' work embedded in this thread
With numbers and data-sheets that aren't necessarily reliable, users need some video demonstrations to help them out 
while heavy-handed hammering and Noss-style destruction videos are oft mocked, they do help dispel concerns users might have about the fragility (or lack thereof) of their tools, especially in the "SHTF" hypothetical scenarios so often discussed in General.
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So Elmax is M390's tougher brethren (According to the Uddeholm) and S35Vn is tougher than S30V. So for a large knife which would you prefer, Elmax or S35Vn. I have always thought that Elmax would be the toughest, but my info comes from excellent post like this and Nathanthemachinest post comparing Elmax, 3V and A2 in his 6" fighter design. I don't own large knives in either.
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I don't take many photos, but I did post a couple earlier. You can see in one photo a 154CM blade that was hammered through a 6d common nail (Home Depot) without obvious damage, but there was some micro-chipping that exceeded my photography skills. I do this test on all steels I try and from time to time repeat it to ensure nothing is wandering off course. It's a dead easy test, but certainly not calibrated. I hit the back of the blade with a hammer hard enough to sever the nail which is resting on a 2 x 4 with the side of the head hammered into the board so the nail lies flat. I agree that destruction testing is useful, but it needs to be in the context of what you're trying to learn. All steels fail and a single test by itself doesn't say much unless you have another steel or two with identical edges also tested in the same way to give you a sense of how they comparatively fail. When I've hammered an S30V blade through the nail, there was no damage. None. Doing the same with S30V left a just barely discernible flat spot, maybe 1/32" long on the edge. So which is tougher? Strike an 8d nail driven into the board and bent to 45 degrees and you'll quickly see which is tougher, but for practical purposes, both will serve quite well for almost any heavy use application, if properly shaped and finished.
I especially like something you said at the end of your video. "It has nothing to do with the steel, that's all just geometry." I couldn't agree more and people should really be focussing on that more than fussing too much about joules and ft lbs. In my experience, geometry will influence how well your blade holds its edge and whether it will be meaningfully damaged by incidental impacts on hard materials.
I especially like something you said at the end of your video. "It has nothing to do with the steel, that's all just geometry." I couldn't agree more and people should really be focussing on that more than fussing too much about joules and ft lbs. In my experience, geometry will influence how well your blade holds its edge and whether it will be meaningfully damaged by incidental impacts on hard materials.
Ankerson
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Yeah, I have whittled nails before and pounded edges through them myself... :thumbup:
It's a good test....
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Probably not. I don't have experience with CPM-D2, but I like PSF27 which is pretty much the same.
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Wow, Jerry this is awesome, can I ask knowing what I just saw in your photo, for someone with some bench stones and regular sharpening equipment, all things being equal, which is easier to reprofile and fix?I have never seen 3V chip from a single impact, even on steel. It will deform for sure, but I've not seen it chip. Then again, I don't make "fine" edges. Sharp edges but not thin, fine edges.
Wild ass guess, M390, but "it depends".
Here is a photo of a test done on S30V and another steel that is particularly noted for its toughness. Same test, same impact on the same target for both steels. S30V chipped, the other was deformed. Same damage to both. Picture a scale, extreme brittleness on one end and extreme weakness on the other. The ideal blade steel will fall exactly in the middle; it won't chip, it won't deform. There is no such steel, but some come close.
View attachment 480086
Here's another photo. Two steels, the bottom one is 154CM, the top one is a steel that scored high on CATRA and had great Charpy marks, but... Both were hammered through a nail with as close to the same impact force as I could achieve. See what happened to the high scoring steel? The company had high hopes for this in the knife world, but decided to look elsewhere for a market. Numbers...
View attachment 480090
Edited to clarify. "Bottom one" meaning the one underneath - top edge in the photo. Sorry.