The Complete Knife Steel Guide: MagnaCut, AEB-L, 14C28N, D2, S35VN, and More

At some point in the knife shopping process, you've likely encountered a product description that reads something like: "CPM-S35VN powder metallurgy stainless steel with a Rockwell hardness of 60-62 HRC." And if you're like most people, you nodded, assumed it was good, and kept reading to find out what color the handle came in.

This is the rational response. Understanding knife steel shouldn't be complicated, but the names often make it harder than it needs to be: a mix of letters, numbers, and acronyms that feel like classified government codes. AEB-L. 14C28N. D2. MagnaCut. They tell you something, just not in any language that maps to everyday human experience.

Once you understand the actual logic behind these materials, the names stop being intimidating and start being useful. And if you're spending real money on a knife built to last decades, understanding what's in the blade is worth ten minutes of your time.

This is that ten minutes.

The Only Three Things That Actually Matter in Knife Steel

Every knife steel in existence is making a set of trade-offs across three properties. Everything else, the branding, the origin story, the price, is downstream of this triangle:

Toughness is the steel's ability to absorb impact without chipping or cracking. Think of it as the "survive a bad day" metric. A tough steel bends before it breaks. A brittle one chips cleanly, often at the worst possible moment.

Edge Retention is how long the blade stays sharp under actual use. This is largely a function of hardness and carbide structure. High edge retention is great in theory; the trade-off is usually that harder steels are more brittle and harder to resharpen.

Corrosion Resistance is how much the steel tolerates moisture, sweat, salt, and acidic residue without developing rust. This is determined primarily by chromium content. More chromium in solution means better corrosion resistance, but getting chromium into solution rather than locked up in carbides is one of the central engineering challenges of modern knife metallurgy.

No steel maximizes all three. And that's not a limitation of current technology. It's a fundamental metallurgical trade-off. A knife maker's job is to match the right trade-offs to the right knife.

"Steel names are like wine vintages. People drop them to sound informed, but most of us are just nodding and hoping for the best."

A Brief Word on Steel Types

(Before We Name Names)

A few categories worth knowing:

Stainless vs. semi-stainless vs. carbon steel. The dividing line is chromium: 13% or more in the alloy, and you're stainless. Below that, you're not. Carbon steels can take an incredibly sharp edge and are beloved by traditional knife makers, but they rust with enthusiasm. Stainless steels are more forgiving. The most famous semi-stainless, D2, sits awkwardly in between.

Tool steel vs. powder metallurgy (PM) steel. Traditional tool steels are melted and cast, which means carbides can cluster unevenly as the steel cools. PM steels (like anything with "CPM" in the name, which stands for Crucible Particle Metallurgy) are atomized into fine powder and then consolidated under pressure. The result is a far more uniform carbide distribution, which translates to more consistent performance and better toughness at higher hardness.

Heat treat matters as much as the steel itself. This point deserves its own section later, but keep it in mind as you read: a mediocre steel with an excellent heat treat will outperform a premium steel with a lazy one. The alloy is the potential. The heat treat is how much of that potential gets realized.

The Steels

AEB-L: The Razor's Edge (Literally)

AEB-L has an interesting backstory for a knife steel: it was developed for razor blades. Not knives. Razors. The kind that needed to achieve almost surgical sharpness at high volume, hold that edge through a shave, and resist corrosion in a wet bathroom environment. Swedish steel company Alleima (formerly Sandvik) engineered it to hit all three of those marks.

As a result, AEB-L has an unusually fine carbide structure: the microscopic particles that determine how a steel performs at the edge. Fine carbides mean the blade can be ground to a thinner, more acute edge without it crumbling. It also means it sharpens with remarkable ease. A well-tuned AEB-L knife responds to a whetstone the way a well-maintained car responds to the accelerator: quickly, predictably, with feedback that tells you exactly where you are.

Fact worth knowing: AEB-L was engineered for razors before it ever met a knife. That razor heritage is exactly why it achieves such exceptional sharpness and why kitchen knife makers and custom blade smiths have been reaching for it for decades.

Hardness typically lands between 61–63 HRC in a good custom shop. Corrosion resistance is good, and it won't rust unless seriously neglected. Toughness is high. The honest weakness: edge retention falls behind the harder powder metallurgy steels under sustained, abrasive use. It dulls faster. But it sharpens back up faster, too, which depending on your perspective is either a trade-off or a feature.

Best for: Kitchen knives, skinners, fillet blades, and any application where achieving a razor edge matters more than holding it indefinitely. Also excellent for anyone who sharpens regularly and values that process.

Where Rucker uses it: AEB-L is one of our two primary steels. For kitchen cutlery and fine-edge work, it's the right call: it brings the sharpness performance of a razor with the toughness to handle daily kitchen demands without chipping on a hard squash or an errant tap against the cutting board.

14C28N: The Overachiever Nobody Talks About

14C28N is, in a very real sense, AEB-L with better corrosion resistance. Also Swedish, also from Alleima, also descended from razor blade steel. The "N" in the name stands for nitrogen: Alleima added it specifically to keep more chromium in solid solution (rather than tied up in carbides), which boosts corrosion performance without the usual penalty to toughness.

"14C28N is the kind of steel that makes a metallurgist nod slowly and approvingly while the internet ignores it for something with a flashier name."

The result is a steel that punches well above its typical price point. Toughness is among the highest of any stainless knife steel. Corrosion resistance is genuinely excellent: better than AEB-L, better than many far more expensive options. Edge retention is middle-of-the-road, which sounds like a knock but really means it sharpens easily and frequently. Hardness typically runs 58–62 HRC.

Brands like Kershaw and Gerber have been using it for years in knives that retail for under $100, which tells you something about its cost-to-performance ratio. It's the kind of steel that rewards knowing what you're looking at.

Best for: EDC blades, outdoor and hunting knives, coastal or humid environments where moisture is a constant factor, any user who wants low-maintenance stainless performance without paying premium steel prices.

D2: The Budget King With a Complicated Reputation

D2 is not a stainless steel. Technically. It contains about 12% chromium, one full percentage point shy of the 13% threshold for stainless classification. Much of that chromium gets locked up in the large carbides that give D2 its legendary wear resistance, rather than staying in solution to protect against rust.

Fact worth knowing: The carbides that give D2 it exceptional wear resistance also tie up the chromium that would otherwise protect against rust. It's a semi-stainless steel, which means: it can rust. It just takes longer.

D2 earns its following through sheer cutting performance at accessible price points. The large chromium carbides make it extremely resistant to abrasion: it stays sharp through hard, repetitive work longer than many more expensive steels. Hardness runs 58–62 HRC and the wear resistance is real.

The honest trade-offs: those same large carbides that provide wear resistance also reduce toughness, making D2 more prone to chipping under hard lateral impact than a PM steel. It's grumpy on the sharpening stone: those carbides that resist wear also resist your diamond rod. And it will rust if you neglect it. Sweat, saltwater, acidic residue from food: D2 notices all of them.

For a working knife that gets maintained and used hard, D2 is excellent value. For an EDC that lives in your pocket through a Montana summer, you might want something more forgiving.

Best for: Hard-use working blades, budget EDC for disciplined users, applications where maximum cutting performance at accessible cost is the priority.

S35VN: The Industry Standard for Good Reason

S35VN has a creation story that says a lot about how seriously the knife world takes this stuff. In 2009, Crucible Industries, the Pennsylvania steel company behind the CPM process, developed it in direct collaboration with Chris Reeve. As in, the maker of the Sebenza, one of the most respected production knives ever made. Reeve had been building knives on the predecessor steel, S30V, and worked with Crucible specifically to fix S30V's tendency toward edge chipping.

The solution was niobium. A small addition (0.5%) refines the carbide structure, making it smaller and more evenly distributed. The result: 15–20% better toughness than S30V, with no meaningful loss in edge retention. Better machinability for makers. Better grinding characteristics. A steel that felt, to production knife makers and serious enthusiasts alike, like it had thought about the end user.

S35VN runs 14% chromium, properly stainless, and typically heat-treats to 58–61 HRC. Edge retention is high. Corrosion resistance is excellent. It's not the easiest steel to sharpen but rewards a decent whetstone. And it is, in 2025, ubiquitous: you'll find it in premium production knives from Benchmade, Spyderco, Chris Reeve, and dozens of others.

Fact worth knowing: S35VN was developed with direct input from Chris Reeve, one of the most respected knife makers in the world. When a legendary craftsman collaborates on a steel's molecular design, the result is a material that reflects real-world use, not just lab specs.

Best for: Premium EDC, tactical, hunting knives. The reliable all-rounder in the premium tier. If you want a single steel that's excellent across most civilian use cases and is available from reputable makers at a fair premium, S35VN is a very sensible place to land.

CPM MagnaCut: The Steel That Changed the Conversation

In 2021, metallurgist Dr. Larrin Thomas published a paper introducing a new knife steel. Thomas runs Knife Steel Nerds, arguably the most rigorous independent source on knife materials science. He spent years studying why conventional PM stainless steels couldn't simultaneously max out toughness, corrosion resistance, and edge retention, and then designed a steel to fix it.

The insight was chromium carbides. In most stainless steels, chromium forms carbides during heat treatment. Those carbides improve hardness and wear resistance, but they pull chromium out of solid solution, reducing corrosion protection. And they're large, which limits toughness. Thomas's approach was to eliminate chromium carbides almost entirely, keeping the chromium in solution where it protects against rust, and instead building wear resistance through smaller, tougher vanadium and niobium carbides.

The result is a steel that, for the first time, genuinely scores well across all three legs of the triangle simultaneously.

Fact worth knowing: In standardized 72-hour saltwater testing, MagnaCut showed no visible corrosion. CPM 20CV, a highly regarded stainless premium steel, showed rust spots under identical conditions. MagnaCut's corrosion resistance approaches that of specialized marine-grade alloys.

At 62.5 HRC, MagnaCut delivers roughly 38 ft-lbs of toughness, approximately 40% more than S35VN at the same hardness. Edge retention lands between S35VN and S45VN. It sharpens with good feedback on stones and responds well to stropping. It can be heat-treated anywhere from 59 to 64 HRC depending on the application.

"MagnaCut is the kind of engineering solution that makes you reconsider what trade-offs you've been accepting. Not because the other steels were bad, but because the ceiling just moved."

There are caveats. MagnaCut is premium steel at a premium price. It also demands a premium heat treat to realize its potential: the difference between a great MagnaCut blade and a mediocre one is almost entirely in the heat treatment. Buy it from a maker who controls their own process and knows the steel.

Best for: Hunters, outdoorsmen, serious EDC users, anyone who wants the closest thing to "best available across the board" and is willing to pay for it. The future-proof choice if you're buying once and buying well.

Where Rucker uses it: MagnaCut is our other primary steel, and it's where we've placed our bets on the modern premium tier. The combination of corrosion resistance (Montana rivers are cold and unforgiving) and toughness (a field knife needs to take impact without protest) made it the obvious choice for our outdoor and hunting line.

The Comparison at a Glance

Ratings are relative comparisons, not absolute scores. Heat treatment affects every column.

A Word on Heat Treatment

The best steel in the world, poorly heat-treated, loses to a cheaper steel done well. Heat treatment is the process of heating and cooling steel in precisely controlled sequences to achieve a target hardness and carbide structure. Done right, it transforms a raw alloy into a high-performance tool. Done carelessly, it wastes the alloy's potential entirely.

A few things worth knowing when buying a custom knife:

Ask about target hardness. A specific HRC target, and a reason for it, is a sign the maker has thought carefully about the blade's use case. Vague answers are a yellow flag.

Ask about sub-zero treatment. Cryogenic (sub-zero) treatment after quenching converts retained austenite into martensite, improving hardness stability and long-term performance. It's a step that costs time and equipment, which is why it's often skipped. It shouldn't be.

Buy from makers who control their own heat treat. Outsourcing heat treatment introduces variables. A maker who does it in-house has accountability for the result, and usually, pride in it.

At Rucker, we heat-treat our blades in house with the same attention to detail that goes into every step of the process. Most people will never see it, but they'll notice it every time they put the knife to work.

So, Which Steel Should You Buy?

The right steel depends on what you're doing with the knife and how much you're willing to pay attention to it.

On a budget and want real cutting performance: D2 rewards disciplined maintenance and delivers excellent wear resistance at a price that doesn't require a long conversation with your spouse.

Want low-maintenance stainless EDC that's easy to sharpen: 14C28N is the underrated answer. Better corrosion resistance than its price implies, easy on the stones, forgiving in the field.

Kitchen or food prep work: AEB-L. Nothing gets sharper more easily, nothing performs better on food, and the ease of re-sharpening means you'll actually keep it sharp.

Premium EDC with a proven track record: S35VN. Battle-tested, widely available, and designed with real end-user input from one of the best knife makers alive.

Best all-around and future-proof: MagnaCut. The ceiling moved in 2021. If you're buying once and buying well, this is where the steel conversation currently ends.

Frequently Asked Questions

What is the best all-around knife steel? For most users in 2025, CPM MagnaCut is the strongest all-around choice. It's the first steel to achieve high toughness, excellent corrosion resistance, and strong edge retention simultaneously, a combination previously considered impossible in a single alloy. S35VN remains an excellent and more widely available alternative for those who want proven performance at a slightly lower price point.

What is the difference between stainless and semi-stainless steel? The distinction is chromium content. A steel with 13% or more chromium in solid solution is classified as stainless. Semi-stainless steels, like D2, contain high chromium, up to 12%, but much of it gets locked in carbides during heat treatment rather than staying in solution to prevent oxidation. The result: better rust resistance than carbon steel, but not as reliable as true stainless. It can still rust. It just takes longer.

Is D2 a good knife steel? Yes, for the right use case. D2 delivers exceptional wear resistance and holds an edge well through hard, abrasive work at an accessible price point. The honest trade-offs are toughness (it can chip under lateral impact more readily than PM steels) and corrosion (it is not truly stainless and requires maintenance). For a maintained working knife, it's excellent value.

What does CPM mean in knife steel? CPM stands for Crucible Particle Metallurgy, a proprietary process developed by Crucible Industries. Rather than melting and casting steel in conventional ingots (where carbides can cluster unevenly as the metal cools), CPM atomizes molten steel into fine powder, then consolidates it under high pressure. The result is a far more uniform carbide distribution, which improves toughness and consistency at high hardness levels.

How does MagnaCut compare to S35VN? MagnaCut is the technical successor. It's approximately 40% tougher than S35VN at equivalent hardness and significantly more corrosion resistant, approaching marine-grade alloys in saltwater testing. Edge retention is similar (slightly above S35VN). The trade-offs are cost and heat-treat dependency: MagnaCut requires a careful, precise heat treatment to reach its potential. S35VN is more forgiving and widely available. If both are well-made, MagnaCut wins on paper and in the field.

Is AEB-L good for kitchen knives? Excellent, in fact. AEB-L was developed for razor blades before it was ever used for kitchen knives, which should tell you something about its sharpness potential. It achieves a very fine, acute edge, sharpens quickly and with good feedback, and has enough toughness to handle daily kitchen use without chipping. For cooks who sharpen regularly and prioritize a razor edge over maximum durability, it's one of the best options available.

Rucker Knives are handmade in Northwest Montana. Every blade we ship is heat-treated in-house, sub-zero treated, and hand-finished. If you have questions about which steel is right for your custom order, we're happy to have that conversation: info@ruckerknives.com