I’m still scraping planes lately, dragging my feet on my chisels, and making some plane irons where necessary for scraped planes. I guess not getting the chisels done is an attention deficit thing. When work is busy and there is deadline pressure, I tend to want to explore things because exploring and getting better quickly at something is engaging to my mind.
That said, I read things fairly often about steel. People talk about it a lot. Often it’s about preferences and then explanations. I feel like from experimenting, there are a lot of things that result in properties I like, but I don’t always know why they do. It’s more important that I can get a result than it is that I can explain it. Why? Because trying to explain the why instead of the what, or put differently, feeling an obligation to explain things when you know the what and have never tested that your “why” is true leads to a lot of false information.
There’s a discussion going on on SMC at this point that’s got several nuggets in it. One is attributing ability to plane certain woods to an alloy when the attribute making the difference is hardness. I’ve mentioned before that O1 and V11 both have similar toughness levels and both have a similar working hardness range. Toughness is an impact test – how much energy comes out when breaking things. In my experience, O1 has a third attribute that’s generally better – edge stability. Stability is a nuanced term used for knives that basically implies the ability to hold a fine edge. Not just any edge that will go through an abrasive laden machine sharpness testing card, but the kind of property that makes small chipping less likely in one steel vs. the next. At any rate, LV tempers their O1 soft, and XHP/V11 is tempered sometimes (at least in the irons and a single chisel that I had) at the upper range. Figure these are 59/60 respectively and 63. You probably would not recognize O1 as being the same steel if you used two irons, one at 60 hardness and the other at 63, and didn’t know what alloy they are.
That aside, all plane irons are forged
Clifton was the last maker of planes that I can remember advertising that irons were forged. I don’t know what they were doing, but I’m sure someone does. I suspect they were drawing steel to length mostly. I don’t see an advantage to doing this and there’s a non-zero chance that the results could be worse than using rolled material and an established process.
Things happen with steel when you’re forging. The grain direction is altered, but grain is also enlarged, and you have to grind, normalize and do whatever else needs to be done after that. But normalizing will be important because the distribution of carbides is not always ideal after forging. Maybe it never is, but at least sometimes it’s not. Why? Carbides can form at grain boundaries creating a layer rather than being neatly spherical or tubular sitting at grain boundaries, but not separating them.
I don’t know what happens industrially, but Clifton’s forged irons were well liked. I think the stamp was actually their biggest differentiator, but so was the price here. The last I saw them at highland, the price of an iron was about double that of any others.
Normalizing steel re-establishes grain. Annealing after normalizing or doing something else to adjust the structure before quenching changes more things – from the state (martensite, pearlite, etc) before subsequent steps, and you can refine grain smaller and adjust the shape of carbides (types of annealing can do that).
Rolling is Forging
If you buy rolled flat stock, the steel has already been elongated and widened by rolling. Rolling is a type of forging and if the steel is not spheroidized, it probably comes with carbides that are more tubular. It definitely has the benefit of continuous grain in steel, and grain is important in terms of edge orientation. Even though grain is established by normalizing, for reasons I don’t know, there is a bias for toughness based on rolling direction.
Nobody here has ever used a cast plane iron, or one that isn’t forged. Even PM products are rolled into bars. Forging at one point was important before modern rolling or die forming (rod) or drawing out because steel that’s as cast won’t have the same toughness or orientation. if you go back far enough to steel like wootz, it was necessary to get layers of toughness alternating with layers of carbides.
Brent Beach had an interesting page on edge life, but what it left behind was also comparative pictures of edges that provide other information. For example, the Clifton iron pictures are here:
https://brentbeach.ca/Sharpen/Cliftontest.html
The edge performed fine. If you want to see ugly results, you can go to the main page and look at the Shepherd irons. I had one of those from a plane kit and mine as equally horrible with surprise failures aplenty out of nowhere. Even looking back now, I have no clue how they made irons of such low quality unless they were really bargain hunting stock.
Back to the comparison – Steve Knight offered O1 irons that were cryogenically treated. I know that instantly brings some folks to suggest there’s no reason to do that because it’s for A2 or other highly alloyed steels. Larrin Thomas (Knife steel nerds) also addressed this well in discussion of various cold treatments. Cryogenic treatment mostly trades some toughness for additional hardness, and it’s true that it’s beneficial to A2 because the toughness is coming from retained austenite (something we don’t want too much of it) and liquid nitrogen converts that to martensite (something we want a lot of). If steel has enough toughness, we usually will like something that’s gotten cold treatment more than something that hasn’t.
Steve’s O1 iron pictures are here:
https://brentbeach.ca/Sharpen/Knighttest.html
Notice the fineness of the edge. The footage planed isn’t the same so it’s hard to make the call for sure that steve’s iron would also have planed longer than the Clifton iron – I’d bet on worse than even odds that it would’ve planed somewhat longer, though.
Steve said at the time “I don’t know what cryo does, but it makes it better” when anyone at the time insisted that it was only for A2. you may recall those days, when we generally didn’t talk about anything but “vintage steel, chrome vanadium, O1 and A2”. Ahh…the same days where folks insisted that chrome vanadium steel was gummy and cheap and less fine and full of stuff that’s not in “good old plain carbon steel”. What most of it was lacking was a good quality melt and roll and, especially, enough carbon to get into the low to mid 60s. It’s less alloyed than O1, though, not more.
Back to Steve’s irons – why were they better than Clifton’s in this test. Finer and probably long wearing? Because they are – the combination of the rolled material and then the process applied before heat treatment and then the cryo made for a better iron.
I had a couple of these irons, but no longer have any, or I’d give you an idea of their hardness. They were bonkers hard without being chippy. They were just good.
I have forged irons from rod (stanley replacement irons) and they are fine. I think the forging got more stuff in solution in my case and the result is the irons are a bit hard and hard tempered, but not faulty. Hard tempered meaning they are bitey and drop their wire edge quickly. Day to day, are they any better than the first good irons I made with starrett steel just by heating to nonmagnetic, a little further past that and then quenching and tempering? i don’t think so. They’re a little different, but I can’t say that perception of properties is more than a slight difference in hardness.
The quality of the stock and then the quality of the process applied after shaping is really what makes a difference. Just as terminal hardness and not alloying is almost always what makes a difference in perception about what can work in really hard woods and what can’t.
Of Making by Hand with Wood and Steel 