Category: General Maker’s Thoughts

1095 is a steel that most people think of when they mention modern handsaws or card scrapers. Or perhaps older knives and some current kabar knives. Except none of those knives are actually 1095. They’re a modified alloy with chromium and vanadium.

But, you can’t really get that publicly.

I had a relatively lengthy post – OK..all of them are – about solving 1084. Solving 1084 had to do with just how fast grain grows in 1084 if it’s overheated a little. Other steels seem to like a fast overheat just before quench, and 1095 is one that doesn’t suffer too much. but….

What’s wrong with 1095?

You’ll probably never see 1095 in commercial tools other than spring steel. It’s really cheap, and it tends to have some of the manganese (hardenability) replaced by chromium, presumably because just adding carbon to 1084 results in a really brittle steel.

Chromium takes up some of the slack for missing manganese in terms of hardenability, and 1095 is what you would call a high hardness steel with poor hardenability. The former refers to hardness potential. The latter refers to have fast steel has to cool to get there. 1095 needs a fast quench. Parks 50 is the only thing I’ve found that gets it right. You can screw around with water/brine and intermittent quenching or whatever else, but Parks 50 and a very thorough quench will probably harden better than anything you can do with water that doesn’t end in cracking.

I have since found “solving” 1095 that it’s tolerant of a little temperature overshot, which probably has to do with having chromium in the alloy. But less tolerant than 26c3. So if you’re going to quench it, heat it past nonmagnetic a little but not too much and not for too long, then quench it as fast as you can and get it to the lowest temperature you can at the end of the quench as fast as possible. For me, this is parks 50 for a couple of seconds and then immediately to cold water after the high heat has been removed, and then into the freezer. This sounds stupid, but I leave a band of frost on the freezer and within about 30 seconds from hot like to stick a plane iron or chisel to the frost in the freezer and then I leave it in the freezer while the tempering toaster oven and the “metal sandwich” that stabilizes temperatures heats.

But….that’s not what’s wrong with it. What’s wrong is two things: 1) there’s nothing really in 1095 that will prevent a soak from getting and leaving a lot of carbon in solution – far more than the eutectic limit. 2) I don’t think the quality of 1095 that’s available now is that great, but some is good. And I’ve been warned by several people that the quality is iffy.

All three sources that I’ve used for bar stock have been different. It’s nice to find someone who lists the alloy, and then purchase whichever source has the highest chromium level. And hope that it’s quality – if it’s not, move on.

What about #1, though? if steel has too much carbon in the lattice, and not in iron or other carbides, the form of martensite is different and it can be filled with small cracks. If you get 1095 just right, it’ll be about as tough as O1. if you don’t, it might be half as tough, and in my experience, that’s enough of a problem to have a chippy plane iron.

I still like it better than 1084 when it’s done right as far as plane irons go. Why? it feels sharper. I can’t think of a real reason to use either 1095 or 1084 for plane irons at this point, though. 80Crv2 makes a better plane iron than 1084 and 1095. But it’s nice to experiment, and if you can really nail 1084 and make it work at high hardness, and the same with 1095, it will improve your accuracy and make heat treatment of other steels better.

Three Tries – Three Different Steels

First, I sent samples to Larrin Thomas without thinking much. I just applied the same heat treatment routine that I would use for O1 and 26c3. I think this causes a little bit of grain growth. Keeping the thermal cycles tighter (right at the point nonmagnetic starts to occur and then let the steel cool) will keep the grain from growing and keeping the temperature overshot lower will keep grain small but beyond just the looks, the result is slightly less hard. My 400F samples were 63.1 hardness and something like 4.3 ft lbs toughness. You’d expect something more like 61/62 and 8-10. Had i tempered them further, I have no clue – maybe they’d have been OK.

After solving 1084, I did the same with 1095, snapping samples and both observing grain size and seeing how easily they broke untempered. Steel should break easily when hit with a hammer untempered, but there are alloys that retain austenite at a high % that would prove that wrong. None of the plan steels that I’ve tried will resist breaking though. Breaking tempered steel would be more accurate in terms of actual usable toughness, but high toughness steels can become really hard to break so I don’t do it – the grain is the focus.

The first 1095 that I bought was from New Jersey Steel Baron. Since I didn’t have Parks 50 at the time, I was kind of unimpressed by it. It was also very cheap, so I didn’t care that much and put it aside. fast forward to now and I like the version that New Jersey Steel Baron sells. I try to avoid anything that would resemble a soak to maximize the amount of carbon in carbides. I do this with a pre-quench and then a sort-of anneal in vermiculte, and then do as much as possible to not go past nonmagnetic for thermal cycles before quenching.

Still, the result isn’t exactly a cornucopia of carbides and I haven’t found the free lunch. But the early samples that I made showed almost no carbide and I’ve gotten to this point. The iron may be a point softer, but the edge holds up. And the straightness of the edge is wonderful. This uniformity seems to be important along with an edge that doesn’t look very rounded right at the tip (AEB-L, for example, wears longer, but the edge shows a more rounded profile – I don’t know why this is).

The second 1095 that I bought was from Alpha Knife Supply, which is where I get 26c3 (love it for chisels, obviously). The listing doesn’t reveal the mill but mentions that if you want great quality, finding bohler or ordering a melt from bohler is safe – or something to that effect. So, it’s probably not bohler, or the listing would say. This 1095 seems to have some oddness in it – not terminal by any means, but the shiny spots in it look like something that wasn’t fully dissolved, and I didn’t normalize the steel or do anything unusual, it’s just bar stock, so I think this is how it arrived. This bright spot wears just a little slower and leaves a stripe on wood that can be seen but not felt.

The AKS sample here is actually the first one I got right, and I puzzled about the stripes in use until getting the blade under the microscope. If the iron isn’t very good, there will be defects, anyway, so you don’t know right away if you did something wrong or if it’s the steel. It’s *rarely* something in the steel.

In an effort to find 1095 with more chromium, or more like an an observation while browsing for other steels, I found that USA knife maker had a listing with chromium near the upper end of the spec range and also had added nickel. The results of that are also good, just as the NJSB version. There’s no guarantee that some of the vendors aren’t selling wholesale to each other or selling from the same wholesale source, so the first and third pictures could be the same stuff just from different sellers.

I don’t see much there, but will take another shot at wearing one of these irons. it seems the key to getting a really robust view of the carbides has to do with setting the cap iron closer and wearing more deeply in to the back of the iron.

nonetheless, this iron seems to work well.

I haven’t done any roughing of wood lately so I don’t know if toughness will be an issue. These irons subjectively wear a little less long than 80CrV2 or O1, but not too much less. the edge quality is nice and they feel more crisp than 1084.

But I also can’t think of a practical advantage to continue to make or use them. It’s just nice to get them right.

1095, like 1084, is cheap. if it costs more than $7 of bar stock to make an iron, I’d be surprised.

I sure would love to get a hold of the Sharon 50-100B (I only have the version without vanadium) or Carbon V or whatever Kabar is currently using to make knives. I get the sense that the extra chromium and the vanadium do the same favors they do in 80CrV2 and the toughness would be greatly improved enough to maybe be worth using that steel in chisels as well as plane irons.

I heat treat in a propane forge. That generally means I can’t do what’s important for stainless steels, which is a high temperature soak. I can do the other part of the need for chromium stainless steels, which is get a small area of steel really hot. But along with breaking the rules, this is usually highly controlled for temperature and duration, and temperatures that you really can’t get away with in the open atmosphere.

Instead of doing that, I preheat steel quickly to above critical, let it cool just back to where critical would be and then ramp up temperature by eye to as hot as I can as quickly as I can and quench. I’m aiming for almost yellow and not much exposure time to open air and then quench and get to cold as fast as possible. Stainless and high chromium steels often will cool with plates just fine, but I’m just tinfoil hatting that I will come up a little short and I want the quench to be fast.

Is this a long term plan? No. If a stainless shows potential, then at some point, I will either get a furnace or I will send a batch off and give half of them away at cost. But I’m not there yet.

V11 is Somewhat Stainless

A few years ago, two posters on woodworking forums talked about an XRF of V11 showing that it is CTS-XHP. I don’t know if it is exactly, but the composition matched CTS-XHP spec. XHP is a relatively high carbon steel with enough chromium to be referred to as stainless – very high if you’re used to numbers like 0.8 or 1%. I don’t know enough about steel chemistry except to speculate that a lot of the chromium gets tied up with carbon when the carbon content is high and stainlessness won’t just be discernible by percent of chromium because chromium has to remain in the lattice and it even has to remain in the right place in the grains in the lattice. Put differently, a very very low carbon steel may be very stainless with 13% chromium, but XHP is only borderline stainless if you’re really going to neglect a knife.

Why did I bring up V11? I learned that the high temperature soak for stainless steels that frees elements to go back into the steel’s lattice/solution before quenching isn’t just important for dissolving chromium carbides. If you reason that you don’t need to do that and you can just heat it and quench it at a lower temperature, it will lack hardness. As in, you can’t just reason that you’ll work with what’s already in solution quickly and get hardness – it comes up short.

That comes to play here. I’d suspect that if you’re willing to make XHP really hot really quickly and quench it and then run it to the freezer very quickly after finishing the tail end of the quench in water, you can get 60+ hardness after temper. That is, you can get close to the furnace schedule. In doing this, you’re relying on the bars from Carpenter Steel being good quality to start. It seems to be fine.

Here’s another why – XHP has a lot of carbides in it, and it’s a little lacking in toughness in chisels. There’s a little something else going on that I don’t know – it could be volume of carbides (cracks start in carbides) or it could be lack of the same directional property that some other steels have. the following link shows a micrograph of XHP, the white “balls” are carbides, you can read the entire page which is half history lesson at knife steel nerds.

AEB-L, however, is a completely different animal.

What is it?

First start with the micrograph (you can click this)

Notice how fine it is? It’s much lower in carbon. XHP is about 1.6% carbon and AEB-L is about 0.67% carbon. A drastic difference. I’ve quick heated it in the past without knowing just how important the high temperature is and it makes a kind of soft iron that needs to have the edge buffed to not fold. Then it planes a long time, but that’s no good.

AEB-L is also cheap – it’s a steel used to make razor blades. Knife steel nerds also has a nice write up on where it’s used. Just follow the link above and search for AEB-L.

An interesting side fact here is the idea that PM steels are the finest grain-wise ignores reality. PM allows steel compositions that would be too coarse if it cooled from a large ingot, but it doesn’t negate the fact that there are other compositions that are very fine without needing a powder process. This results in AEB-L being finer than any powder metal stainless that I’ve seen.

What’s the Draw of Fine Grain?

Somewhere this seemed to imply “it’ll be like carbon steel but stainless”. That’s kind of true, maybe? If you read about AEB-L, it can be done in furnace and finished with a cryo dip after the quench to get very high hardness and still have good toughness. 64, in fact. it should hold up at high hardness better than XHP/V11, be finer grained, and I surmised maybe a little easier to sharpen.

So, yesterday I gave heat treatment another try concentrating heat just on the last inch of the plane iron, quick quench, finish in the freezer. I don’t know what the hardness is, but it must be close to 60 as it shows no ills. It also appears from pictures following that there’s no evidence of suffering anything from not being soaked – for woodworking purposes at least. it would be interesting to see what it’s like at high hardness, but I don’t have the means to get the steel any harder.

Suddenly vs. prior samples, this sample has strong hardness and it’s not quick to hone. Prior versions of this had planing test edge life of 1.6 or 1.65 times more than O1 steel. I’d need to use this iron planing for about 2500 feet in edges just to test that once, and I don’t really have the desire right now.

The reality is that wear resistance makes it slower to sharpen and it is. It also makes it grind kind of hot, which isn’t what we want. It’s not a high temperature tolerant steel and the temper is 350F in the sample here. Grinding it to an accidental brown edge will have undesired effect.

This is part of the conundrum with steels like XHP and now confirmed with AEB-L, too. When you grind these steels, which you’ll be doing a fair amount if you use tools much, the steel wears more slowly and it grinds less cool. XHP takes about twice as long to grind even without considering that and AEB-L speculatively took me twice as long to establish a bevel on a belt grinder. Just estimating based on wear life in wood, AEB-L would grind only about 60% as fast, but that’s compounded further by having to stop more to dip.

Overall, finally getting a hard sample and that’s a little bit of a road block to day to day use (it’s annoying). But it’s worth having a look at how it wears.

This image is the wear after 540 feet. It wears slowly and the wear area looks so odd because of the lack of any visible carbides even at 300x optical . I usually get wear pictures on carbon steels to see carbides at only about 200 feet of planing on cherry. If this iron felt like carbon steel in wood – like in a free lunch way – longer wearing, feels the same – I’d consider planing a volume of wood.

But, it doesn’t. I don’t know why for sure, but I’m starting to get the sense that some carbide volume right at the edge makes for an edge that wears more thinly somehow.

So, this iron would last a long time, but it doesn’t have the feel that carbon steel does, and strangely, XHP/V11 with its high carbide volume has a really keen and sharp feel. Its achilles is that in less than perfect wood, it takes nicks like anything else, or maybe even a little easier, and grinding and honing them out is twice the work.

So, I think I’m back to using plain steels. Too bad. if I ever get a furnace and a dewar of liquid nitrogen, I’ll consider trying to make a very high hardness sample and see if the edge is different.

So…..razor blades? I don’t think AEB-L is ever used in a plain razor blade. I think it’s used as the steel stamping, then it’s honed, and then the edge is coated with something hard. You can see ads claiming razors are platinum coated or whatever – I have no idea what they are actually coated with, but I have honed the coating off of them before when they are dead to see if they can be resharpened, and what’s left is just steel that’s too soft to work at an acute edge.

Steels that d0 well in straight razors rather do have a relatively large volume of carbides compared to AEB-L, but they’re iron carbides and not chromium carbides.

Free lunch yet again not found.

But I have confirmed previously that this steel, which is slower to sharpen but not difficult like steels with a lot of vanadium, will wear much longer than A2 steel and it’s creeping up on XHP – and it’s cheap. About $10 per plane iron in steel costs.

I have no idea if the qualities of picking up shavings more easily during a wear cycle are important to the average user. They should be for anyone who may be sometimes planing several hundred board feet from rough each year as how easily the shaving is picked up is far more important in terms of effort than how many feet are planed carefully in a test. This same factor is why I don’t care for 52100 – it will technically wear longer, but it requires more effort from the person using the plane to keep it in the cut as it dulls and that just isn’t very practical.

For Reference

Here’s how much wear I encountered in the O1 test on the same board after 540 feet. You can see that a great deal of wear has occurred rounding a larger section of the edge and forcing me to increase the light level significantly.

Half the price of O1 and at least as good in plane irons. I put off even considering this alloy for chisels because the data sheet shows it being around 60 hardness at a 400F temper. I find favor with most 1% and higher steels around 400F, but admit that I don’t have a great reason to believe that it’s the best temperature for everything.

The other thing against 80CrV2 is that it’s a not an expensive steel but it’s not as cheap as it could be with some retailers, and the prices is around what you’d expect for O1. While making an order a couple of weeks ago, I found that NJ Steel Baron doesn’t charge too much more than the very lowest cost HC steels like 1084 and 1095.

So, what is it? I’ve never heard of it as a woodworker, but saw someone else attribute a statement to Larrin Thomas that it is used in woodworking tools. If you’re purchasing LN, LV or other boutique tools, it’s probably not going to be there. Maybe it’s used in carving tools and plane irons in europe, or maybe it’s used in what are lower class chisels for woodworking, but the top of the range hardware store chisels in the $15-$20 each. I really don’t know.

From 1084 and 1095, the Troubles

1084 and 1095 gave me trouble until I snapped samples to see what color and time they will show before grain growth is a problem. 1095 isn’t too bad, but 1084 is a different story. Shoot a little too high before the quench and grain growth doubles. Do that while thermal cycling and the point of cycling gets lost, plus the quench. You have to be attendant with it, and give it only a few seconds if chasing the quench temperature up and not nearly as high as something like 26c3 will tolerate. Put differently, the routine that I used to better any published results for 26c3 results in *very* poor 1084.

I’d hoped to find 1095-ish with chromium and vanadium. The former to add some toughness without sacrificing hardenability, and the latter to pin grain size, allow for the overshot that I like to ensure hardness. It’s not to be, and 52100 just isn’t very good for woodworking.

1084 also will not ever wear as long as O1, but it does OK. that isn’t a problem with chisels, and the toughness of 1084 was good enough once I solved not growing grain that it will make a fine plane iron tempered a little lower. Translation – it can be as hard as O1 and 1095 will tolerate planing.

Seeing the better than expected corrected version of 1084, I made a couple of plane irons out of 80crV2 and used an offcut that was waste off of the same sheet and snapped samples. The grain is as fine as anything I’ve ever seen that attains high hardness, and the hardness was a little better than I expected starting with a 375F double temper. I suspect it’s around 61/62, about the same as O1 tempered at 400F.

I’m going to avoid going into a broad discussion about how much carbon is in solution (not in carbides) in each of the steels, but for brevity, some steels suffer from too much of it remaining in the lattice and not in carbides. The resulting toughness vs. pictures of the snapped grain or micrographs can seemingly be 1/3 of expected. This isn’t always bad – o1 is far less tough than 52100, but it’s nicer to use.

What is it?

Despite the dreaded “chrome vanadium” name, it is not some soft shiny steel that makes a terrible chisel. That label given to the variety is ill attributed because someone knew the combination of favorable properties – limiting grain growth and toughness, but paired them with a low carbon amount – often 0.5 or 0.6% carbon. This isn’t really much good for woodworking, and the 0.6% variety is listed a lot in not-quite-hard-enough-chisels from China. When I reharden them, they are only a little better – there’s just not much potential.

80CrV2 is 0.8 or 0.85% carbon, manganese of about 0.4% (just over half of 1084), Chromium taking place of some of the manganese (0.5%) and a small amount of vanadium (0.2%). It’s a water hardening steel, so we’re not likely to see any of the boutique US makers making it. The chromium and vanadium are enough to make it more friendly to heat treat than the plainest of steels, but they won’t make it feel gummy or slick like A2, etc.

In woodworking, you will often see O1 labeled as plain carbon steel, but if you work with older tools or 1095 or 26c3 or whatever else of that sort, you’ll notice the feel of the alloying in O1. it’s not bad, but you can feel it. it’s more obvious in 52100 due to the chromium content (1.5%), and, of course, once you get used to plain steels, A2 feels terrible. V11 also gets its slickness for a huge dose of chromium.

I can’t well compare grain size from snapped samples with 80CrV2 to anything else I have because I had to double the magnification on my hand scope to 100x optical to see any difference in samples just heated from bar and quenched, then thermal cycled and then the same as the latter but with an intentional simulated careless overheat.

Here’s the snapped sample from the quick heat at 100x:

Next, the same magnification but with three thermal cycles.

that’s outstanding. Even looking at this under a loupe you can’t see much.

Here’s the kicker – doing the same thing as above but allowing the sample to overshoot in 15 seconds to a very bright orange resulted in….wait for it.

Nothing. This is not a long duration forge heat, so it’s not license to just disregard what temperature does to steel. This would be more like what a beginner may unintentionally do. It may look at first sight like the second picture shows larger grain than the third, but I think that the actual sample had a little more toughness breaking and if you look at the individual grains, you’ll find them similar in size – especially given the limitations of snapped samples being photographed with a microscope that I got for $12.

1084 steel is constantly recommended to beginners. I think they have no chance if they’re using a forge. This is what beginners should be starting with. But the forgiveness allows more advanced forge heat treaters to get otherworldly consistent results without being as taxing as 1084.

There is toughness in reserve with this steel, so it would probably hold up in a plane iron tempered hard (like 63/64). Hard tempered irons are OK, I guess, but I generally like something around a hardness that the washita likes – somewhere around 62. More hardness means slower sharpening and the sharpening effort seems to increase faster than any footage gained planing.

So, How Long Does it Wear?

About the same as O1 – which is nice, because 1095 and 1084 don’t last that long, and neither does an old Ward iron or an iron made of 26c3.

To test this, I planed a single board alternating with an O1 iron that I already have and one of the new 80Crv2 irons, and I took pictures of the carbides about 2/3rds of the way through. I want to see how long each planes, but discern difference in how the edges feel because there’s a fair chance I may start using this stuff in my own plane irons.

The bottom line is at similar hardness, the edge life was almost identical. On the cherry board with a chosen shaving thickness, I planed 783 feet with 80CrV2 and 778 with O1. When clearance runs out, it lets you know ahead of time, but when it tips over toward not allow the plane to pick up a shaving, it seems to happen all at once. the margin of error in this test is probably 25 feet of planing, so figure these are about the same. that’s all I need to know.

Pictures of the carbides – O1 first, and since there was a lot of heavy edge wear, I had to turn up the light on the microscope. What I’m looking for is a nice even edge, and even carbides.

In the 52100 post, I showed O1 with much less wear. This is Bohler O1 and I think the others was starrett. But the real difference is far more war, exposing more shadowing with carbides in the worn edge. That is, some part of them is pointed directly back at the lens wheras the edge is rounded and appears dark because it reflects light elsewhere. there are a few odd carbides here or there, but these are seemingly 2 or 3 microns. Maybe they’re tungsten.

Now, the 80CrV2:

These are extremely high magnification (300x optical – the height of the picture is less than 1/100th of an inch in reality), but look at the tiny evenly dispersed carbides. The slightly different shape in the wear – who knows, it could be just how the steel wears or slight differences in cap iron setting. nonetheless, anywhere you see anything that looks like it’s even 2 microns, it’s probably two carbides close together.

it felt just a little sweeter. The evenness of the edge probably shows why.

So, what are we looking at in costs? A sheet of steel that will make 6 stanley plane irons costs $32.50 as I type this. There’s enough left for half a dozen marking knives or several nice kitchen paring knives. After allocating shipping to this sheet, we’re in the ballpark of $6-$7 an iron. bumping up to Lie-Nielsen or Infill thickness irons and the cost goes up a little bit, but I’d consider making a few LN replacement irons as there is no alternative to dumpy A2 now. I don’t have LN planes any longer, but I do have spokeshaves, and the A2 blades for them are just a terrible choice.

What about Chisels?

26c3 is probably unbeatable – it sharpens easily, it attains really high hardness easily and the crispness of the edge is superb. It’s not nearly as widely available, either.

But I will probably make a few 80CrV2 chisels just to see what they feel like at 350F temper and then down from there (or up in temperature and down in hardness). I think 26c3 is easy to get right, but a beginner may not have much chance of doing that in a forge, and my test samples bettered published specs, so I would be hesitant to guess how good it is in a furnace. The knifesteelnerds suggested heat treatment doesn’t get results that I get, and I think that’s a shame, but the steel itself may also not have that much value to knife users who can be wooed with the promise of something better that isn’t functionally better.

And in all fairness, though I have not a single positive thing to say about Devin Thomas, Larrin is the one who in his characteristic brevity when I asked about a 1% CrV steel, suggested 80CrV2, and maybe seeing the suggestion the 15th time tipped me from feeling like I didn’t need to short carbon well below 1% because I have the skill to work with steels more difficult ….to trying it anyway.

Would We Ever See it in Boutique Tools?

I doubt it. There are some things that I do to chase hardness that require hands on skill and some experience. I’ve now probably heat treated at least 300 items and I have not just heat treated them, but I have been using it as a fun exercise to try to get better and more consistent. I’ve also never had to do it on a Tuesday afternoon with a hangover or organize 50 items at a time. If I harden and temper 10 items in a busy week, that’s a lot, and I usually limit what I’m doing to cycling two items at a time. I’m kind of dumb, and trying to keep track of more than two things that are changing colors and in and out of the forge is a good way to make a mistake.

Well, to start out with, I ended up getting banned from a knifemaking forum because I wanted to talk about heat treating in a forge. But I really went there in the first place to try to find 1095 with upper end of the spec chromium and a little bit of added vanadium. That would make forge heat treatment really easy. It turns out, you can solve (if you’re me) the issues with 1084 and 1095 pretty easily just by manipulating temperatures by eye with some samples, snap them, and then make actual tools with them and confirm they’re better. But I didn’t bother to do that until I got berated about “poor results” from one of the most undesirable individuals I’ve ever met on a forum – Devin Thomas – the father of the metallurgist who did my test results for 26c3 and O1. I later sent more samples, as I’ve mentioned on here, with 1095 and 1084 without looking much at them just to see how they’d turn out.

The 1095 was mediocre and the 1084 was undertough by a lot. What resulted was finding out that though I’ve never talked to Devin, he was pretty pleased to see the second set of results from steels I don’t generally work with and pretty excited to ignore the fact that my other samples were as good (O-1) as book results and never-to-be-mentioned, I guess, far better than furnace schedule results for 26c3. Those weren’t by chance.

What is the problem? Apparently, Devin, who is by others accounts an accomplished maker and provider of some materials to other knife makers, doesn’t like anyone to talk about heat treating in a forge. I don’t really care what he likes, but he doesn’t know much of anything about woodworking tools and I couldn’t get discussion out of anyone else about questions that had nothing to do with it. He gets my award for the least desirable person I’ve come across on any forum for inability to discuss something unrelated to what he wants to drone on about. So, eventually I got banned for talking about heat treating in a propane forge and posting the results because I refused to stop talking about it. The official reason “poor behavior and being suspected as a returning troll”.

This is BS, of course – I don’t have more than one ID on any forum and have a distaste for people who maintain multiple logins. I can’t think of a single person who does that and adds anything positive to any forum.

I may also be underestimating the whims of advertisers on the forum or other paying service providers. In short, talking objectively about what you’re doing and after much goading, showing factual results that aren’t in line with assertions you weren’t asking about in the first place? It must be some kind of threat.

The very simple fact is that by not following published schedules, I got better results than anyone has ever published with 26c3, and it breaks the rules of not normalizing steel and then giving it an austenitizing soak before quenching. I had no idea those things were supposedly rules in the first place. they can be needed for some steels that do need them – 26c3 doesn’t. If far better results than steel done with those steps isn’t proof, I have no clue what is.

What resulted when I was found out to be a forge heat treater and then my comment that I wasn’t getting a furnace in the near future, from Devin, is something I wouldn’t have expected to see from a grown man, but life is full of surprises. I did later scroll back and find out that i’m not the only person who has been subjected to it, and there’s a whole group of (maybe well meaning?) sycophants who will request the moderators ban anyone who posts methods they don’t like. I suspect posting results that support them is even less well liked.

Where does 52100 come into this? I got the same thing I always get from people who have made knives when I don’t mention 52100 as a preferred steel.

What’s the problem?

52100 is very different than other relatively plain steels. It has an amount of chromium in it that gobbles (binds) a lot of carbon so that the carbon doesn’t remain in the lattice/grain framework. It’s also offered in a lot of inexpensive bar stock in very different starting structures. Some of those structures won’t achieve good hardness, especially if you just heat it to nonmagnetic and then quench it.

I have worked enough with it to know that I can get it reasonably hard in the quench – to the point that it’s difficult to deal with sharpening comparatively – in woodworking tools.

The lack of carbon in solution appears to make it too tough. This is a foreign concept for knifemakers – “too tough”. Tough keeps people from breaking knives – they bend instead. I don’t think people have the cajones to return a knife they bent but that didn’t break and then claim they weren’t abusing it. That’s great for a maker. Let’s be honest, too, few people are doing much with custom knives they buy outside of some really strange competitions that look just ourtright weird to anyone who is a woodworker. The average person is pushing a knife through things or slicing with said knife.

When I first started playing with it, I expected to find low hanging fruit, that 52100 hadn’t been used, and maybe it was a mistake not to use it. Maybe the reason was that it was harder to heat treat, or who knows what. I suspect that the early 1900s tools from the carbide patterns that I see are lightly alloyed water hardening steels with some addition of tungsten, and some may be oil hardening steels when they’re solid. but I don’t think I’ve ever used a tool that behaves like 52100.

Everything used in woodworking has enough toughness, but not an excessive amount. You wouldn’t expect to take a chisel, bend it over in a vise into an L and bend it back and not have it break, but 52100 can do things like that without breaking outright.

First Experiements

I made a couple of blades of all kinds. 52100 was one of them. Disregarding effort made, it planes about as long as O1. I didn’t test it directly against O1 right away and figured it should be good. it also has a persistent wire edge at “normal” plane iron hardnesses. In chisels, I found the toughness intolerable – when an edge would deflect it would just stay there increasing the cross section of the edge and making the chisel harder to get through wood. An unexpected problem.

I later compared a couple of the irons that planed about as long as O1 and noticed that as the two steels wear, 52100 takes more effort to keep in the cut and on woods that a plane likes to come in and out of the cut on (figured or runout), the cut was more rough at the same interval. that creates a big difference in physical effort even if both irons plane the same distance, and planes not staying in the cut is part of the reason the average person fails to get a finish ready surface off of a plane. This is what the carbides looked like – they were a little larger than I would’ve expected, but evenly distributed and all in all, not bad.

Compare the edge of that picture to O1

I think there is a fundamental difference in how the edge wears – how round or blunt does it get, and how does that effect planing.

O1 does not keep carbon out of solution the same way 52100 does and the alloy is different, but it’s easier for a fast heat treatment process to get a lot of uniformity. I think moving the cap iron around would show a few more carbides, but it’s not a surprise that they aren’t as vivid. the “stuff” remains in solution and creates a problem that metallurgists call plate martensite. This problem reduces toughness…..except for woodworking, I’m not convinced that it’s a problem.

Knife folks are still fixated on the fact that you can break O1 – what are they cutting? I don’t know. I think they cut the cheese more than they cut things with their knives. We don’t have that luxury in woodworking.

I keep coming back to O1 being a really pleasant steel for woodworking, but I’m not trying to create an argument for it – I’m working from outcomes first, which can be unexpected – it shouldn’t be better according to anyone, but if it shows better in outcomes every time, and it’s also easier to heat treat, and the issue of toughness doesn’t apply to us, maybe it would be smart not to deny the outcome. Even if you never figure out the cause, the better performance is right in front of your face. And if you hand plane 15 or 20 board feet from rough in a day, that difference will be drastic. It can work longer into the dulling cycle without you as the “planer” having to sharpen as often or you as the planer leaning on the plane and really creating a lot of problems that are both unpleasant and unproductive.

I also noticed while looking at grain size that these 52100 samples were outright abusive to my vise. I break samples by hitting them with a hammer. I want to see the grain size under a microscope – but you can also feel a difference in how hard you have to hit the steel to break it. A tempered factory file will break easily. A 3/16″ thick sample of 52100 that’s even moderately tempered may actually be a threat to break a vise.

what does that clue us into? the next reasonable thing is to leave it hardly tempered or untempered and see if the edge holds together. it’s really unpleasant to sharpen when it’s left really hard, but it’s not that slow to grind. the washita won’t touch it. Why is this reasonable. It’ll be much less tough at really high hardnesses, but it may still be tough enough almost untempered to plane wood without chipping.

Figuring it would chip and then I would walk back the temper until it didn’t, I was wrong. it didn’t chip untempered. It was, however, a right bitch to sharpen when compared to tempered irons. Slower even on diamond hones. there’s nothing in it diamonds won’t cut easily, but at some point, harness can be so high that the diamonds don’t penetrate as much.

But…compare the edge to O1. I don’t know if the picture is meaningful, but the edge rounded look is still there………and the result of planing is that it again felt really keen initially and then continued to plane, but it doesn’t have the sweetness of O-1. the combination of attributes doesn’t offer anything. Again, a surprise.

I Put it Aside and Got it Out Later

After being goaded on the blade forums (and then banned for talking about forge heat treatment, or because of the outrage that the topic causes), I decided I’d see if I could get some of the carbides in solution without a furance. I don’t think this would be that hard. Here’s the thought process:

Larrin posted an excellent article about how much differently 52100 turns out in a furance depending on the initial microstructure. Some of this is canceled out by the fact that I use a temperature overshot when heating and no real duration, but probably not all of it.

When I first used 52100, i heated it a couple of times and quenched it, and tried a few things. Since then, I’ve learned to shrink grain with extreme reliability. I also think I can manipulate carbides a little bit without having too much carbon escape the steel. Again, a very high heat overshot, and then something I haven’t done before much – heat to critical with another iron (for mass) and stuff it in vermiculite. the hope is that I will get carbon back into solution (less toughness, higher hardness yet), and the thermal cycles will shrink grain without moving much of the excess carbon in the lattice back into carbides.

I would then follow this up with a temperature overshot quench (heat to a brighter orange as fast as possible then quench as fast as possible back to the lowest temperature possible). I have all of these mule irons on hand already, they’re just waiting to be turned into knives or something instead, but if I can actually change how they look under the scope, I will know I’ve changed the outcome without any question as to the difference in the bar stock used.

So, I did this – I know conceptually this is difficult to follow. But here are the same irons with microscope at same magnification. Apologies if the light reflection is slightly different.

First iron, 350 F temper, which would be untertempered for O1:

I would estimate this first iron’s hardness at 62 based on the stones. the washita doesn’t do much with it, but it’s not intolerable. it cuts OK on an india stone. As with prior versions, the burr is persistent, but I’ll let the buffer deal with it.

This is after planing. Look at the edge again – it still looks like it doesn’t have the uniform sweetness.. And it doesn’t. It just doesn’t perform as well with thin shavings.

The hardness is a little better that before. Did I do what I think I’m doing? I have no idea.

so I did one more iron with the same thing, one of the ones previously made, and tempered it at 300F instead. It should be around 64 hardness. It feels like i is. the washita has no interest in it. For reference, the abrasive particles in washita are about the same hardness as rockwell C64. If you slurry an oilstone, it can abrade steels harder than the particles, but the mechanism isn’t by rasping grooves in the steel.

this harder iron is unpleasant to sharpen if you’re used to something like 62 hardness O1. It’s not more abrasion resistant, it’s just harder.

The edge is maybe slightly finer and if I didn’t take too thin of a shaving, the plane wasn’t unpleasant to use. However, it wasn’t better to use than 62 hardness O1. it still exhibits more of a decline in ease of use through the dulling cycle.

I’m not sure exactly what I’m seeing, but I think for this steel and for 1084 at higher hardness, the edge wearing actually forms a bit of a burr, too, or something that reflects light in an unexpected way.

Whatever it is, the outcome remains the same. It’s just not as nice to use on wood.

And, I think that fact – that you can feel the difference and anyone actually making tools when people were acutally using them could feel the same has a lot to do with why we don’t see ultra high toughness steels in woodworking. No matter how much some knifemaker tells you “it doesn’t make any sense”.

The sharpenability of lower alloy steels like this at really high hardness is there, too. It doesn’t make sense to someone not sharpening in volume why it would be an issue, but you don’t get double the edge life for double the sharpening effort, and that’s ultimately going to be annoying to experienced woodworkers.