CPM MagnaCut (opens in new tab)

It's a good question; unusually, that doesn't mean I don't have a good answer.

Steel is so far from being a more or less uniform substance that it's not even funny. There are four major phases that play roles even in the commonest carbon steel (ferrite, cementite, austenite, and martensite), plus others that can form at times like graphite, which plays an important role in cast irons. Ferrite and cementite can form nanolaminated microstructures called pearlite and bainite which have a major influence on the properties of the steel, and there are other microstructures that form depending on cooling speed, heat treatment, and cold working. So even the simplest steel is a nanostructured composite of metal and ceramic whose properties are hard to model computationally, though great strides have been made in recent decades.

Then, once you add other alloying elements besides those two (intentionally or not), steel stops being so simple. You can find phase diagrams for most of the binary systems (vanadium-carbon, for example, or vanadium-iron) but most of the ternary systems probably include compounds that haven't been identified yet. In theory you could find them computationally, I think. Even when you have a phase diagram, though, that doesn't tell you how fast the phase transitions happen, which depends on things like the crystal structures of intermediate unstable phases.

I don't know anything about this stuff, I just read about it. Recommended! Start with https://www.tf.uni-kiel.de/matwis/amat/generalinfo_en/guided...

This is actually a great question and doesn't deserve to be downvoted. Indeed this is one of the considerations that led me to leave materials science research field after a couple of undergraduate projects with PhD candidates.

It turns out that the domain between Angstroms (where we can computationally model atomic interactions accounting for quantum effects) and Milli (where standard Newton's laws and therefore mechanical engineering tools can be used) is a vast computational desert.

Most properties that affect bulk material properties happen to be developed in the micro-domain (note the photographs in the article) and almost 20 years after I've left the field, I don't believe there's still any rigorous "first-principles" based computational approach yet. In other words, materials are not uniform in the micro domain and this is where materials properties develop.

So materials research process becomes hypothize, create material batch, test it 20 ways, rinse and repeat for a slightly different composition or process

Even the software mentioned in the article (thermo-calc) is primarily empirical with some very smart extrapolations and modeling added (note the first step is experimental data capture [1]. It definitely is a massive step forward from when I was in the field but definitely not first principles based modeling.

[1] https://thermocalc.com/about-us/methodology/the-calphad-meth...

Former computational materials scientist here. There are groups that are using ML for finding materials to simulate, and some beginning to use it to speed up simulations. Still that said, simulating cutting, abrasion, sharpening (I suppose it would be called to some extent tribology) is still in the infancy of simulation. Steel is extra difficult compared to other materials, and it has such a history of innovation that all exists at a sort of mesoscale out of reach of contemporary atomistic simulations. Still some have attempted it: https://www.dierk-raabe.com/icme/ or more recently: https://www.sciencedirect.com/science/article/abs/pii/S09270... Still the from Simulation/Search -> Experiment pipeline is working generally at much smaller scales that steel structures for now. ie micro instead of nano

The search space is much, much more vast than you'd imagine, and there are so many ways that things get non-linear that we have absolutely no idea how (way) more than 99.9999% of the possible alloys that we could make would actually perform in reality. The way most of the alloys we are using were found was that we started with something that we already knew, and then tweaked from there to optimize some property.

Per TFA, it is to an extent? The author briefly discusses a computational search of the design space, and uses that data to encourage the partner company to make a batch of the steel.

That said, simulating material properties from atomic scale principles seems nontrivial compared to predicting them given observed parameters and properties of other alloys. I’d be interested in more informed comments on that possibility!

The important qualities of steel emerge out of microstructure: nanometer to millimeter sized features (several different crystal structures in the same material interacting through the boundaries between them and the bulk properties in them) which requires quantum interactions to be tracked through many orders of magnitude of scale. This includes how these different structures are formed though many stages of melting, tempering, work hardening, etc. In other words it is hideously computationally complex.

One of many fields where yes there is a lot of simulation and yes it is developing but still quite far from having anything close to a complete model which can escape the need for extensive experimentation.

There is a sort of prevalent idea among people outside these fields that simulations exist which can just handle anything. This is very wrong and quite far away.

AFAICT that is, to a large degree, what the author did. Much of the initial "exploration" seems to have been done in Thermo-Calc, with physical experiments following. IMO the novelty in process is more exciting than the novelty of the result.

There's a startup out of U of Toronto working on exactly this:

https://www.thephaseshift.com/

No. This is knives, not science.

The first batch was given to smaller makers, often custom makers. Right now, Tactile Turn is offering a couple knives in MagnaCut (change the option in the drop down). I've seen people say they have used up their MagnaCut already. The steel will probably trickle into the market.

Spyderco announced that the Native 5 Salt will come in MagnaCut. No date has been given for that.

https://tactileknife.co/products/rockwall-thumbstud

The post is more about the steel than the knife. The steel is quite new to market, so not many knife manufacturers have picked it up yet. However, here's one I found for you.

https://www.knifecenter.com/item/SP41SYL5/spyderco-native-5-...

Dawson Knives have numerous models:

https://www.dawsonknives.com/collections/home-page

The thing is, there's no such "best" steel. It all depends on what you want to do with the steel. I'm sure a custom maker will make a MagnaCut chef's knife, but I don't think you'll notice much of a difference. The corrosion resistance should be great, and that goes a long way with easy of maintenance, especially when cutting things like tomatoes. But most kitchen work is done on a cutting board (hopefully plastic or wood), and the material is quite soft. You can make a good argument that MagnaCut isn't needed in the kitchen.

MagnaCut wasn't developed for the kitchen. Even though I am a self-professed "knife person" I just don't rely on a knife all that much where I would notice the difference between MagnaCut and VG10. So, on paper, MagnaCut is a big step forward compared to pretty much every steel. But that doesn't mean every steel is not obsolete. And, of course, we all have preferences. We like what we like, even if another option is "better" in some way.

52100 is a great steel. Sharpens like a dream. Sometimes, that's all that matters to a person.

I have family members who refuse to clean knifes properly. I need stainless steel. Personally, I'd prefer to have high carbon, but I know it'd be a rusted mess in a month.

any recommended brands? or are these custom made?

MagnaCut is the first knife steel that does the best job of balancing edge retention, toughness, and corrosion resistance. It is basically a stainless 4V (if that means anything to you). Larrin focused on reducing the amount or chromium needed. Lots of steels will dump chromium into the steel to help corrosion resistance. This only helps if chromium remains in solution and not forming carbides with the iron. Chromium carbides don't offer much in the way of wear resistance (unless you have a ton of them like in ZDP-189) and they are large carbides (relatively speaking) even after the particle metallurgy process. Basically, you give up toughness when helping corrosion resistance (ignoring steels with nitrogen). Larrin uses a lower amount of chromium than you would expect, but it remains in solution. So you get the stain resistance you want without the chromium carbides.

Other benefits of the steel include grindability, which means makers can spend less time and abrasives on shaping the knife. You can obtain higher hardness than a standard stainless steel, which helps with forming an apex and removing the burr (sharpness for lack of a better word).

Spyderco, a major player in the knife world, has a line of knives called their Salt series. These knives are supposed to be as rust-free as one can make. MagnaCut will first enter their catalog as a Salt knife. This was a big shock given how well LC200N (nitrogen-based steel used by NASA for ball bearings) can resist rust and remain tough (wear resistance isn't anything special though).

Bottom line, Larrin built a well-balanced steel exclusively for knives. Many steels are adopted from other industries or were "knife-specific" but based on something like 440C, which was never intended for cutlery. So MagnaCut is upending the knife steel market by offering something you can't get elsewhere.

Knife nerd comes up with an idea for how to make a steel with a novel combination of hardness / toughness, edge retention, and corrosion resistance. Persuades a real steel company to make a batch, which is tested eighteen ways from Friday by him, the company, and a bunch of knifemakers. Result turns out to be as good as predicted, maybe even a bit better.

Bonus making it even more relevant to HN: most of the "discovery" was done via software, before any physical experiments (which are hard and expensive in this case). The fact that this new approach yielded good results is promising wrt developing steels with different properties.

new steel good

Larrin's father is a famous custom knife maker who worked with making his own Damascus-style steel. Larrin, though his father, is well-known among the knife community.

Not really sure I’d call Larrin “someone off the street.” They guy literally wrote the book on modern knife metallurgy and has a PhD in the science. https://www.amazon.com/Knife-Engineering-Steel-Treating-Geom...

He also has a well known website and is considered one of the worlds leading experts on knife steels and knife craft.

He has a PhD Metallurgical Engineering and works in the steel industry (though on automotive steels, not on knife steels). Not quite the same as someone off the street. From TFA the company was mainly worried that his knife-steel knowledge was purely academic (since he's never worked professionally on high carbon knife steels).

I put my Victorinox in the dishwasher with no ill effect. The biggest danger is when a visitor decides to chop a tomoto on a ceramic plate.

It's no Japanese chef knife, but a bargin for what it is.

Why? It literally takes less than 15 seconds to clean and dry a stainless knife.

Thanks. I occasionally read their blog back in the day, but didn't know they were still producing stuff.

If you look at White/Blue/Super funny they will rust. HAP40 is a high-speed tool steel. CPM M4 is a good comparison to it. MagnaCut will offer corrosion resistance that you don't tend to see in Japanese steels. MagnaCut will have better edge retention than White/Blue/Super. Those steels are low-alloy and rely on high hardness for wear resistance. MagnaCut has vanadium and niobium plus it can get pretty hard as well. MagnaCut is so far ahead of White/Blue/Super in this regard. Japanese steels are known for being great to sharpen (even HAP40). From what I have read, MagnaCut sharpens well.

If we say that MagnaCut = stainless 4V and HAP40 = CPM M4, then HAP40 should have some more edge retention but less toughness when compared to MagnaCut. The differences aren't all that great. Corrosion resistance is the real difference maker.

Spyderco already announced MagnaCut in their 2022 catalog. However, they are backed up at the moment. I am not holding my breath for a release in the near future. Custom makers tend to be on the cutting edge (no pun intended) when it comes to using "odd" steels. I expect more and more people to use it. That said, will Crucible make enough for demand? There's not a ton of money in knife steel production. Right now, Crucible's latest cutlery steel is S45Vn. S35Vn and S30V are still widely used as well. 20CV has taken off a bit too. I don't think Crucible will start making large batches just yet. But, I could be wrong.

This knife enthusiast[0] implies that this steel isn't necessary in the kitchen

Though I had the same question, I'm guessing it'll be a few years and it'll be very expensive.

[0]https://news.ycombinator.com/item?id=29697285

I like to cook; I bought a carbon-steel chef's knife 25 years ago, made by Richardson Steel of Sheffield. Regrettably they don't make steel in Sheffield any more, and that brand was sold to some Chinese company. The knife rusts if you let it; I call the result a 'patina'. It takes a wicked edge. It's still my go-to kitchen knife.

Just now I'm a beardie-wierdie; but I usually shave through the summer, using straight razors. These are also carbon steel, although I think one of my razors at least must have some chromium in it - it seems to resist tarnishing.

So: I wonder how this material compares to that Sheffield carbon steel for hardness and toughness. And I wonder how it compares with the Solingen steel my two daily razors are made of. As far as I'm concerned, a straight razor is the pinnacle of blade-making (I might take a different view if I was into swords).

One of my razors belonged to my father, and is Sheffield carbon steel. It was made in the 1930s, and I can't get it nearly as sharp as the modern Solingen steel razors (I tried shaving with it once, but it wasn't 'smooth').

I didn't get what hardening, tempering and annealing processes he applied; that makes a huge difference to the kind of steel you end up with.

I'm just a blade user, not a metallurgist or cutler. I'm just interested in high-performance blades. I wonder if this metal makes nice razors?

Elastic ceramic is a pretty wild material as well. You can do stuff with it that seems impossible with steel.