FC61 vs VG10

Every Miyabi in our registry has “FC61” in its steel cell; every Tojiro, Enso and Yoshihiro has “VG10.” Both are stainless, both run at about 60–61 HRC, and both sit under Damascus cladding on knives from the same Japanese city. So a buyer choosing between a Kaizen II and a Tojiro DP, or between the Koh sujihiki and the Yoshihiro, reasonably asks what the steel names actually mean. The answer is that they belong to two different families of stainless steel — one built around a lot of carbide, one built around very little — and the difference shows up in exactly the two places a cook notices: how the edge sharpens, and how long it lasts.

One rule for this page. We separate what the steel makers publish from what independent metallurgists have measured from what is widely reported but unconfirmed, and we label each. VG10 is easy: its maker prints the recipe. FC61 is not: ZWILLING prints a trade name and a hardness and nothing else, and the most important claim about it — what alloy it is — comes from outside ZWILLING. We will tell you that claim. We will not tell you it is fact.

The decision table

VG10: a published recipe and a lot of carbide

Takefu Special Steel publishes VG10’s composition on its own site: 1.00% carbon, 15.00% chromium, 1.00% molybdenum, 0.25% vanadium and 1.55% cobalt, hardened to “HRC60≦” — 60 and above. Takefu’s own explanation is that the chromium, molybdenum and cobalt “all strengthen the matrix, yielding high hardness, in addition to maintaining a long-lasting sharp edge.” That is the maker’s claim and it is a fair one.

Independent testing fills in what the recipe implies. Knife Steel Nerds measured VG10 at about 60.7 Rc, found its carbide structure to be chromium carbide with “no vanadium carbide,” somewhere in “the 12–16% carbide volume range,” and put its toughness at an average of 5.8 ft-lbs, “in line with other high carbide stainless steels.” Its edge retention tested “a small notch below 440C.” The same source dates the steel to “over 60 years ago” and suggests the cobalt was “likely added to increase tempering resistance” for high-temperature coatings rather than for the edge. In plain terms: VG10 is a high-carbide stainless. The carbides resist wear, which is why a Tojiro DP stays usable for weeks, and they are large and numerous, which is why the burr on VG10 can be stubborn and why makers stop at about 15° rather than going finer. Our VG10 guide goes deeper on the steel alone.

FC61: a trade name, a hardness, and a claim ZWILLING will not confirm

Here is everything ZWILLING publishes about FC61 on the Miyabi Koh page: “Crafted from revolutionary FC61 fine carbide stainless steel,” “Blade hardness (HRC): 61 HRC,” an “Ice-hardened FRIODURx2 blade for exceptional durability,” a “9.5–12° edge angle” from a “Hand-honed, 3-step Honbazuke blade,” and “Handcrafted in Seki, Japan.” The Kaizen II page gives the hardness as 60–62 HRC. No composition. No alloy. No steel maker. ZWILLING does not state what FC61 is.

What is widely reported is that FC61 is a trade name for Sandvik 13C26, which is essentially identical to Uddeholm AEB-L, and that “FC” stands for fine carbide and “61” for the hardness target. The Culinary Knife Bible states this directly; it does not cite ZWILLING for it, and neither can we. The claim is plausible — the “fine carbide” name, the 61 HRC target and the very acute factory edge all fit a razor steel — and it is unconfirmed, and this page treats it as both.

If it is true, the independent metallurgy on AEB-L tells you what to expect. AEB-L is a low-carbon (0.65–0.7%) stainless with 13.5% chromium, developed by Uddeholm in the 1960s as a razor-blade steel, with “carbides of one micron or less” against 440C’s “carbides over 10 microns.” Its toughness at 62.2 Rc “matches the toughness of 59.8 Rc CPM-154.” Its edge retention is “55% of the slicing edge retention of 440C at 59 Rc” — ordinary among stainless steels. It is “not a good choice ... in very corrosive environments like salt water.” That source does not mention FC61 or Miyabi at all; we cite it for what a fine-carbide razor steel measures at, not as proof of what FC61 is.

What the difference means at the edge

Sharpening.Small carbides let a steel take a finer, cleaner apex: there is nothing large at the edge to tear out, and the burr breaks away rather than folding. That is consistent with ZWILLING honing FC61 to 9.5–12° per side — an angle at which a coarse-carbide steel would crumble — where VG10 knives ship at about 15–16°. On a stone, a fine-carbide steel is the easier of the two to get genuinely sharp; VG10 gets there too, with more attention to the burr. Neither needs anything exotic; a 1000-grit water stone handles both, and the Japanese-knife sharpener page covers the tools.

Edge retention.This is where VG10’s carbide volume pays. More hard carbide in the steel means the edge abrades more slowly, and the independent figures — VG10 just under 440C, AEB-L at about 55% of 440C — point the same way. A Miyabi’s edge feels sharp for a long time because it starts extraordinarily sharp; it is nonetheless wearing faster than a Tojiro’s. If you sharpen rarely, that matters. If you sharpen monthly, it does not.

Toughness.The metallurgy favors the fine-carbide steel, and by a wide margin at the same hardness. But toughness is the steel’s property, and chipping is the knife’s: Miyabi spends that toughness on a 9.5–12° edge, and any steel at that angle is more fragile than the same steel at 16°. In practice both knives chip when twisted through a bone; the more acute one chips first. Our chipped-knife how-to is the repair.

Corrosion.VG10’s 15% chromium is a point and a half more than a 13.5% razor steel, and Takefu lists corrosion resistance among its properties. Both are stainless in the kitchen sense; neither should live wet.

The hardness figures are the same, and that is worth saying

Buyers see “61” on the Miyabi and “~60” on the Tojiro and conclude the Miyabi is harder. It is not, meaningfully: Takefu’s own figure for VG10 is 60 and above, the Enso HD publishes 61 for its VG10 core, and ZWILLING gives 60–62 for the Kaizen II. Both steels live in the same one-point band on the hardness chart. What differs is not how hard they are but what they are made of at that hardness, which is the whole point of this page.

Which to buy

Buy FC61if you sharpen regularly, want the keenest edge a production kitchen knife ships with, and value a steel that is easy to bring to a clean apex and forgiving of a hard steel’s usual brittleness. Accept that you are trusting a trade name, that ZWILLING will not tell you the alloy, and that the edge wears faster than it feels like it does.

Buy VG10 if you sharpen rarely, want the longer-wearing edge, and prefer a steel whose maker publishes the recipe so you know exactly what you own. Accept a slightly less acute factory edge and a burr that wants a little more care on the stone.

And if the decision is really between a Kaizen II and a Shun rather than between two steels, the Shun vs Miyabi page compares the finished knives, where the edge angle and the warranty terms end up mattering more than the alloy.

How we compared these

We do not own these knives and have not tested either steel. This page reads Takefu’s own VG10 page and ZWILLING’s own Miyabi Koh and Kaizen II pages for what each maker publishes; two Knife Steel Nerds articles for independent measurements of VG10 and of AEB-L; and the Culinary Knife Bible for the reported FC61 identity, which ZWILLING has not confirmed and which we label unconfirmed wherever it appears. Every AEB-L figure on this page is conditional on that identity and is marked “if AEB-L.” No price appears in this text; prices come only from the live daily check on each pick. Our methodology sets out the rules in full.