Thread: Two surprise offerings in the US - Exoti-steel Irons

(at least at 62 hardness, it isn't biased to sharpen easier, spoiling the edge strength and making it hard to get the edge life out of it in ideal planing).

Larrin just released another non-PM steel that he calls Apex Ultra that is ripe for "chisel shaped object makers" like blue spruce to use in some high hardness crudely made chisel with a pretty handle.

Or some of the other boutique makers who stab fat pieces of metal into a handle and call them fine chisels. I can imagine the oohs and aahs at a steel that can support hardnesses above 65.

Coupla points, D.W: First, theory suggests the finer the particle, the harder it should be to dislodge it from the matrix. Surface area-to-volume ratio goes up markedly as volume decreases, so if we assume the same degree of surface to surface adhesion, the smaller particle should be held "tighter". However, theory & practice don't always align...

Anyway, I guess we are in agreement that chasing ever-harder steels for plane blades is a largely unrewarding exercise. I spent far too many years doing that, but eventually realised there are too many trade-offs to make blunt statements like "this steel is superior to that steel" - so much depends on context!

I do like the couple of PM-V11 blades I have when it comes to putting a surface on some of our really tough woods like gidgee & bull-oak, but for daily working with "sensible" woods (i.e., woods equivalent to cherry & walnut), it's really hard to beat well-treated O1, imo - so easy to put a good edge on it which lasts very acceptably. It's a good balance of the necessary compromises.

One of my favourite blades is the 1084 blade I heat-treated myself for this "thumb plane" (just a slightly fancy block plane):
Adj 1.jpg

My set-up is so crude you'd fall about laughing at it and I was dubious about the steel itself because it seems such a basic, relatively low-C brew, but it was the only vaguely suitable stuff I could get at the time, and the supplier touted it as "a great steel for beginners". "Beginner" is almost too good a description of my skills but somehow, I fluked the sweet spot with the several blades I made (tempered in the kitchen oven after hardening). They're as tough as my good Hock blades, sharpen equally well & seem to have excellent wear qualities. I'm afraid to ever try again 'cos I doubt I'd ever manage a result like that again!

Cheers,

Originally Posted by IanW

My set-up is so crude you'd fall about laughing at it and I was dubious about the steel itself because it seems such a basic, relatively low-C brew, but it was the only vaguely suitable stuff I could get at the time, and the supplier touted it as "a great steel for beginners". "

oh goodness no!! I'm trying to get the message out that if one wants to do a lot of this by hand, there are steels that can be done like that and match book for hardness and toughness and with very little variance and very fine grain structure.

The one thing that isn't needed is high cost. For water hardening steels like 1084, there is some gain using a fast quench oil (several points of hardness), but it's not necessary to give things a first go. For O1 and even XHP (V11), there is no need for a special oil.

I think a small heat source that can be focused into something that will retain heat is all that's needed, and a decent toaster oven or kitchen oven with some sort of mass-adding bits so that temp spikes don't affect temper.

Steels like 10V (especially) and magnacut are out for me because they need a very high austenitizing temperature and a soak to be all they can be (i'm not sure they really need that much of a soak, but larrin says so).

I've been able to get AEB-L (matrix stainless) into its book range for hardness (above 60 tempered) and very good toughness (accidentally dropped a .035" thick parer the other day ...except not just the parer, the tip was held in a k body clamp so that I could dip the handle, and the whole thing fell out of the vise with the knife landing laterally with the tip in the clamp, knocking a chunk off of the handle end and probably flexing the knife blade to 45 degrees or more - nothing broke!!

If there's a deficiency with O1 in really hard wood, I know i've mentioned this before, a minor adjustment to geometry would make it outlast you in anything you could plane....with one caveat...

......in really hard woods with tons of silica, I haven't found *anything* that will plane for a long period without developing nicking. Why that is, I don't know, but long grain in 3500 hardness wood filled with silica is possible with a line free surface.

I made the same chase.

Won't go into the weeds on the reward for hardness when planing - there may be some for going past 62, but a steel has to be comfortable above 62 vs. being pushed, and when steels like 10V are also very hard, they are super slow to grind - it's hard to get an abrasive to get purchase on them.

...

it's taking all of my sense and might to not buy any of these irons just to experiment.

I think V11 irons are good irons, by the way, and XHP makes a nice slicing knife - just that the attribution of their performance is sometimes overstated. It will be with every supersteel iron that comes out. I'm a little more sensitive to edge condition and sharpening effort because the thin shavings are a tiny percentage of my planing, and I just want a fresh edge for them. When dimensioning by hand, there is far less of that (tissue shavings) following the penultimate planing than there would be following a machine planer and having to get the chatter and all surface bruising of the chatter out, too. When I just wanted to set a pointy apex and do smoothing (before going over the cliff), I also just felt like "I just need it to wear a little longer, be a little harder,....".

I didn't address particle sizes. I'm not a metallurgist, of course, but have a functional knowledge at this point of things that will affect hardness and toughness.

Carbide volume, dispersion and particle size:
* cracks in steel originate in carbides in most cases. Once there is any significant volume, SEM images show that it's definitely true. Larrin Thomas has also made comments that either all or pretty much all cracks and thus breaks originate in the carbides.
* the higher the carbide volume, the greater the territory for cracks to start, and then travel into the matrix around the carbides
* it's possible to have an alloying element in a steel (like chromium in magnacut) and play cards right and have it remain in the matrix instead of carbides, maybe more on this at the end. If the element doesn't make it into carbides, it doesn't appear to improve wear resistance, but it may improve other qualities. Larrin suggests that this is why magnacut has such a high volume of vanadium, niobium and chromium, but doesn't have what one might expect in terms of edge life. It approximates 4V in abrasion resistance (same territory as V11).
* carbide dispersion and size can mitigate some of the lack of toughness that comes with carbide volume. Steels like D2 or M4 are much less tough (takes much less energy to snap a sample in half) than their PM counterparts

I don't know if there's a set descriptor for particle size, but when you snap a sample, you can see the fineness. If there isn't grain growth, probably what's visible is carbides. You can't necessarily see this easily with the naked eye, but you can under magnification.

Most discussions about particle size, though, are not going to be for the matrix steel, but rather how big the carbides are. Given the discussion of toughness, having the same volume more evenly dispersed is definitely better for woodworking. Whether or not it makes a difference on large metal contact surfaces, I don't think it does.

That leaves something else that can contribute to lack of toughness - the structure of the *non* carbide matrix in steel. An example of two steels that look alike or close in a micrograph are 52100 and O1. 52100 is a bearing steel and done right, it's extremely tough. O1 breaks with a much smaller amount of energy, and 1095 also does (1095 looks finer than either in a micrograph).

You can add toughness by retaining austenite (at the cost of hardness, and it's not stable, so generally not so good), or by having a good martensitic structure (lath). Steels that have excess carbon but that don't manage to tie it up in carbides very well, like O1 and 1095, have lower toughness than one would expect given the carbide/particle size because the martensite is not the finger-like lathes, but like a pile of plates.



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Summary:
* small uniform carbides
* lower carbide volume
* avoiding plate martensite

all associated with higher toughness.

At some point if you want more wear resistance, you have to have carbides. AEB-L, 3V, YXR-7 (remember those really hard japanese chisels?), all matrix steels that don't have enough carbon to seed large carbides, but they don't have the same wear resistance that steels with higher carbide volumes have. They certainly have plenty for woodworking (AEB-L is between A2 and V11, 3V is around the same), and getting high hardness in some matrix types can be difficult.

Carbon steel around 0.8% is close to being a matrix steel, and 1070 if it were used would probably be really tough, but it lacks post-temper hardness (and nobody who thinks O1 wears fast would tolerate it).


The advantage in this case on a performance basis for magnacut over V11, at least in theory, is that the carbides are denser and much smaller. Whether or not the added toughness matters is something that would only be determined with a lot of use, and there is nobody who is going to document all of this stuff, and the fact that people feel like there is a functional gain for V11 or magnacut over something like good O1 or chrome vanadium drill rod rolled into bar and punched into irons suggests that the people who would think there is a big advantage probably aren't doing enough to know that they're not just assigning an advantage because of confirmation bias.

In knives, there would definitely be an advantage - if you had a magnacut knife, it would last as long as V11, chip out less easily and it would take a larger amount of force to break a knife of the same hardness.

....

When the rubber hit the road, I found high carbide volume steels to be more susceptible to small nicks at the same hardness, but I've never had any tool break in a way that a toughness test measures (impacting a piece of steel and breaking it in half and then measuring how much energy the break absorbed). I have also found that really high toughness steels will form a burr in use and not release it - I don't think there has been much historical use in woodworking of really high toughness steels like 52100 because they end up being more physical work to use. The lower carbon chrome vanadium steels are really really tough, but the edge rolls even when they're close to their hardness limit.

O1s lack of toughness may be one of the reasons people actually like it.


There is no practical use in woodworking for any of the non-PM steels that have really big carbides that are poorly dispersed. Most of those were or are blade or die steels that were introduced late and they're still made in ingot form for dies and contact surfaces where acute edges don't come into play - they're a lot cheaper than the PM versions.

Where this could actually be observed in woodworking tools is D2 vs. PM D2. PM-D2 is sort of between A2 and V11. Ingot D2 itself is a coarse carbide edge-nick-out-of-nowhere good for nothing as far as woodworking goes.

Too, when magnacut is mentioned as being tougher because of the small carbides, it's still not a high toughness steel. It's just high toughness for the amount of alloying in it, but it's not close to the toughness of bearing steels or matrix steels.

There is one hidden virtue of the matrix steels - if you can get them up to high hardness, if they have toughness 3 times that of something like magnacut, you can drive their hardness up until you have equivalent toughness and get similar performance.

AEB-L can be pushed to 64 hardness, it's dirt cheap, and it lasts almost as long as magnacut - and would sharpen easier. It makes an OK plane iron - one that definitely outlasts O1 and A2, but like 52100, there's something about it as it dulls (the shape that it wears, maybe?) that results in less good pick-up of the shaving than some less tough steels.

V11 is chippy, but it doesn't suffer this lack if picking up a shaving as it dulls. it's not like AEB-L and 52100 (worse than AEB-L) are incapable of working, just that you will notice that they have a feeling of running out of clearance earlier but don't actually run out of it. if V11 didn't chip as easily as it does, it would be mostly without shortcoming. But it does.

I no longer have any V11 tools, but I have XHP irons that I made that test and feel the same and show carbides pretty close to identical to the ones in XHP micrographs. Still resisting the urge to buy a magnacut iron but probably won't be able to resist forever. Having "did up" AEB-L thinking it would be dominant and hold a crisp edge due to the lack of large particles (I'd have sounded off loudly if I thought I had something there - it has instead become my knife steel of choice), I wonder how the fine details of feel and looks at the edge compare to V11 - the edge life in ideal work until a plane absolutely stops cutting will be about the same.

Cost no object in kitchen knife, I'd have magnacut over XHP, but probably AEB-L at high hardness over both.

AEB-L doesn't need to be PM to have a fine structure, which keeps it inexpensive - and at the same time, it has a far finer particle size than V11 or almost any PM (and significantly finer than magnacut). All you give up with it is cutting 450 cards in a catra test instead of 550 (A2 would cut about 350, O1 about 300)

forgot one other thing only partially explained...

Larrin commented about the stainlessness of magnacut being a bit of a surprise. Which means that being able to keep the chromium in solution (the basis for stainlessness of most stainless steels) in the matrix instead of carbides may have been a little bit of a surprise, too.

Someone asked him about "thermo calc" or something that sounds like application software to design alloys, and his reply made it sound like doing this is sort of a new thing in steels that have a lot of carbides. In lower carbon steels, it's easy to do - there are no carbides of size in some like 420HC, so the steels remain really stainless.

I have no clue what Larrin apparently did to figure out an alloy that would bind carbon to vanadium and niobium and leave the chromium in the matrix, but it's pretty novel and probably has a whole lot to do with why the carbides are all small.

Here are magnacut's "particles" (carbides in a micrograph)
https://i1.wp.com/knifesteelnerds.co...68%2C581&ssl=1

10V (mostly vanadium carbides)
https://i1.wp.com/knifesteelnerds.co...pg?w=750&ssl=1

XHP (V11 or almost identical according to an XRF posted on sawmill creek - just a question of whether or not the carbon is the same as XHP. Xray analysis doesn't report carbon).
https://i0.wp.com/knifesteelnerds.co...pg?w=750&ssl=1

One of my new favorites - AEB-L (half the cost of even O1 steel)
https://i0.wp.com/knifesteelnerds.co...pg?w=750&ssl=1

And just for reference, why i said D2 is a .
https://i1.wp.com/knifesteelnerds.co...pg?w=750&ssl=1

I have had 154CM (nonpowder stainless) in a buck hunting knife. It's not as bad as even D2, but it was terrible, grabby on sharpening media and losing bits of its edge to nothing more than a plain leather strop. There are some folks in the knife world who like a coarse sandpaper type edge with the burr removed, and for those folks, these big carbides won't make much difference. In woodworking, I don't know where they wouldn't be a pain - I'd make a joke about roughing gouges, but D2 isn't high speed and it also lacks toughness, which doesn't make for a great situation with lathe tools.

PM D2 has plenty of toughness and the carbides are more like 5 microns and nicely round.

(and O1

https://i2.wp.com/knifesteelnerds.co...pg?w=750&ssl=1

often called carbon steel, but there's enough alloying in it that it's not really like the really plain water hardening steel.

I haven't seen carbides as big as this micrograph in my worn samples, though. No have I found carbides as big as the ones in the AEB-L micrograph. )

There's a huge array of micrographs to look at here.
New Micrographs of 42 Knife Steels - Knife Steel Nerds

1095 looks especially impressive. The lack of visible carbides is actually its downfall for chisels and plane irons, though - plate martensite structure. For us plebes, a version of the steel with a tiny bit of chromium and vanadium to pin grain size and get some of the carbon out of solution isn't available.

I have played with 1095 with quench routines to try to establish a set of carbides to suck the carbon out of the matrix and had a little bit of success - different makers yield different sized carbides with the same routine, probably due to different alloys.
https://i.imgur.com/oMNIHVZ.jpg

However, I can end up with an iron that's nice to use, but there's nothing really better about it than O1, which is really easy to heat treat and nail every time. so spending a lot of time to try to get an iron to get up to the point of another one that's easy to make and the stock is much higher quality already (1095 stock often is low quality since there's an end user in edge tools)....doesn't make a great deal of sense to save $5.

Here's a picture (these two are my pictures) of another vendor's 1095.

https://i.imgur.com/sJkE9GW.jpg

That bright spot is a defect - right in the bar. It's several hundredths thick and when I broke a sample, I could see dots of it in the sample. It was never mixed into the matrix properly and didn't disperse in rolling. Too bad. I think the rest of it had potential. The bright mark on the picture actually leaves a dull line on a planed surface. I thought it was nicked when testing the iron and resharpened it a few times before bringing it into the scope.


Knives and other things sold as "1095", like kabar, are not actually 1095. They're a steel similar to what used to be sold as Carbon V. I understand if you are willing to order a melt of several tons, you could still have this made.

At some point, I will contact kabar and beg them for some stock and see if they'll let me have some.

I gave in already and ordered one in #7, 4 1/2, 6...whatever (2 3/8) size.

Will eventually report back on ..well, generally how it is as a plane iron.

Not inexpensive - with shipping and tax about $25 more than a V11 iron. ($95 vs. $70)

I can make an AEB-L iron for about $12 or something including gas. 80crv2 is in the same ballpark.

Not sure that I have a favorite, but 80crv2 and O1 of my own make would probably be those two. O1 is a little bit more expensive, but probably 1/4th in stock and tooling vs. the magnacut iron. But it would rust! (AEB-L wouldn't).