Knife Steel Explained: VG-10, X50CrMoV15 and HRC

Knife steel names look like part numbers because they are. VG-10, X50CrMoV15, AUS-10, SG2, CROMOVA 18 — each is a recipe with a fixed composition, and once you can read one, most of the marketing on a knife box stops working.

This covers the alloys you will actually meet on a kitchen knife, what the numbers mean, and why hardness tells you more than the steel name does.

The trade-off every knife steel is negotiating

Four properties, and no alloy maximises all of them:

• Edge retention — how long it stays sharp
• Toughness — resistance to chipping and cracking
• Corrosion resistance — how well it resists rust
• Ease of sharpening — how quickly you can put a new edge on it

Push one up and something else goes down. More carbon means a harder, longer-lasting edge and a more brittle one. More chromium means better rust resistance and, past a point, a slightly coarser edge. That is the entire field.

Reading the names

German-style names describe the recipe. X50CrMoV15 breaks down as:

• X — high-alloy stainless
• 50 — 0.5% carbon
• CrMoV — chromium, molybdenum, vanadium
• 15 — about 15% chromium

So the name literally tells you it is a 0.5%-carbon, 15%-chromium stainless with molybdenum and vanadium. It is also sold as 1.4116, the German material number, and the two are the same steel.

Japanese names are brand names. VG-10, AUS-10 and SG2 are product names from steel mills — they tell you nothing until you look up the composition.

The steels you will actually meet

X50CrMoV15 — the German standard

Composition: about 0.5% carbon, 14–15% chromium, plus manganese, silicon, molybdenum and a little vanadium.

This is the steel in nearly every German kitchen knife: Wüsthof, Zwilling, Mercer, Victorinox. Half a percent of carbon is not much, so it will never hold an edge like a Japanese blade. In exchange it is very tough, very corrosion resistant, and easy to sharpen on a cheap stone.

It gets criticised for being "soft", which misreads what it is for. A knife that other people will use, that goes near bone, and that will be sharpened by a beginner should be exactly this.

Typical hardness: 55–58 HRC.

VG-10 — the Japanese all-rounder

Composition: about 0.95–1.05% carbon, 14.5–15.5% chromium, 0.9–1.2% molybdenum, 0.1–0.3% vanadium, 1.3–1.5% cobalt.

Roughly twice the carbon of X50CrMoV15 at the same chromium level, which is why it holds an edge far longer while staying stainless. The cobalt is the unusual part — it refines the grain structure, which is part of why VG-10 takes such a fine edge.

VG-10 is the workhorse of mid-range Japanese knives. It is what you get in a Tojiro DP, and it is under the Damascus cladding on a great many knives that do not name it prominently.

Typical hardness: 60–61 HRC.

One practical consequence: VG-10 is usually the core of a laminated blade, clad in softer stainless. The cladding resists rust; the exposed core at the very edge is less protected. A VG-10 knife left wet can spot along the edge line while the sides stay pristine.

VG-MAX

Shun's proprietary variant of VG-10, with slightly more carbon and additional vanadium. Marginally better edge retention and wear resistance. In the hand, the difference between VG-10 and VG-MAX is far smaller than the difference between either of them and a German steel.

Typical hardness: 60–61 HRC.

CROMOVA 18

Global's own steel — chromium, molybdenum and vanadium, with about 18% chromium. The high chromium buys excellent corrosion resistance and costs a little edge retention compared with VG-10.

Typical hardness: 56–58 HRC, which is why Global knives sharpen more easily than most Japanese blades.

AUS-8 and AUS-10

Japanese stainless at roughly 0.75% and 1.0% carbon respectively. AUS-10 sits close to VG-10 in composition and performance, usually a little cheaper. AUS-8 is softer and belongs with the German steels in behaviour.

SG2 / R2 — powder steel

Made by powder metallurgy rather than conventional casting, which produces a much finer, more uniform grain. Around 1.4% carbon and a lot of vanadium and molybdenum.

The result is exceptional edge retention at 62–64 HRC. The costs are real: expensive, brittle enough that it chips if you look at it wrong, and slow to sharpen because the hard carbides resist the stone.

A genuinely good steel that most home kitchens should not buy.

Carbon steels — Shirogami and Aogami

Shirogami (white steel) is nearly pure iron and carbon with almost no alloying. Aogami (blue steel) adds tungsten and chromium for a little more wear resistance.

Both take the finest edge of anything in this article and both rust if you leave them wet for an afternoon. They sharpen beautifully and quickly — the low alloy content means there are no hard carbides fighting the stone.

Typical hardness: 60–64 HRC. If you buy one, read how to care for carbon steel knives first, not after.

HRC: the number that matters more than the name

Rockwell hardness is measured by pressing a diamond into the steel and measuring the indentation. Higher number, harder steel.

The same alloy at different hardnesses is effectively a different knife. X50CrMoV15 heat-treated to 55 HRC and the same steel at 58 HRC behave differently in the hand — the 58 holds an edge noticeably longer. That is why Wüsthof's Classic outperforms other German knives with an identical steel on the label.

Rough guide:

HRC	Behaviour
54–56	Very forgiving. Rolls rather than chips, honing fixes it, dulls quickly
57–59	The sweet spot for a knife other people will use
60–62	Long edge life, needs a whetstone, chips if abused
63+	Specialist. Superb edge, unforgiving of everything

If a knife's page publishes the steel but not the hardness, that is itself informative. Heat treatment is where a maker can cut corners invisibly.

What the marketing words actually mean

"High carbon stainless steel" — means the steel contains carbon, which all steel does. It appears on 0.5% carbon German knives and on 1.0% carbon Japanese ones. It tells you nothing.

"67-layer Damascus" — describes the decorative cladding, not the cutting edge. The layers are soft stainless folded around a hard core, and the core is what cuts. See what is a Damascus steel knife.

"Ice-hardened", "cryogenically treated", "sub-zero tempered" — a normal step in heat-treating decent stainless, in which the blade is chilled after quenching to convert retained austenite. Almost every quality knife gets it. Only some brands print it.

"Surgical stainless steel" — not a real specification. There is no standard behind the phrase.

"Japanese steel" on a knife made elsewhere — usually means the steel was bought from a Japanese mill. It says nothing about the heat treatment, which is where hardness comes from.

Which steel should you actually buy

The honest answer is that steel is the third most important variable, after hardness and geometry — how thin the blade is behind the edge.

A thin blade in mediocre steel out-cuts a thick blade in excellent steel, every time. Steel decides how long the edge lasts; geometry decides how well it cuts while it is sharp.

So:

• Sharpen rarely, other people use your knives, things go near bone → X50CrMoV15 at 57–58 HRC
• You sharpen, you want a fine edge, you are careful → VG-10 or VG-MAX at 60–61 HRC
• You are prepared to maintain it obsessively → carbon steel, Shirogami or Aogami
• You want the longest edge life and cost is not the constraint → SG2, and accept the chipping

The full application of this to specific knives is in the chef's knife buying guide, and the philosophy behind the two traditions in German vs Japanese chef's knives.

Common questions

Is VG-10 a good steel? Yes — it is the reliable middle of Japanese kitchen steels. About 1% carbon and 15% chromium gives it long edge retention while staying properly stainless, and it sharpens without a fight. It is the default recommendation for a first good Japanese knife.

Is VG-10 better than X50CrMoV15? It holds an edge much longer, because it has roughly twice the carbon. X50CrMoV15 is tougher, more corrosion resistant and easier to sharpen. Neither is better in the abstract — they are built for different owners.

Does higher HRC mean a better knife? No. It means a longer-lasting edge and a more brittle one. Above about 62 HRC you are buying a knife that will chip on a chicken bone in exchange for months between sharpenings.

What is the hardest kitchen knife steel? Powder steels like SG2 reach 62–64 HRC, and some carbon steels go similarly high. Hardness beyond that stops being useful in a kitchen — the edge becomes too fragile for a cutting board.

Do I need to know the steel before buying? Know the hardness first, the steel second. A maker who publishes both is telling you they have nothing to hide about the heat treatment.