Aogami Super Steel: Is It Good? HRC, Rust and vs VG-10

Aogami Super, or Blue Super steel, is a high-carbon Japanese tool steel from Proterial (formerly Hitachi Metals). Hardened to 63-65 HRC, it holds an edge longer than almost any other carbon steel, but it has almost no chromium, so it will rust unless you dry it.

Every page selling Aogami Super calls it the finest Japanese carbon steel ever made. That part is defensible. What those pages tend to leave out is the condition attached to it: Aogami Super is a reactive steel, and the edge retention everyone quotes is only worth having if you are willing to look after the blade that carries it. This guide covers what the steel actually is, what the numbers mean, how it compares to the stainless steels most kitchen knives use, and who should not buy it.

For the record: The Cooking Guild does not forge on Aogami Super. Our blades run on 7Cr17MoV, AUS-10, 10Cr17MoV, SLD tool steel and 1080 high carbon. This is a guide, not an advert, and where the comparison lands on one of our steels we say so plainly.

What is Aogami Super steel?

Aogami means "blue paper". Japanese mills historically sorted grades by the colour of the paper wrapped round the billet, and the labels stuck. White paper, Shirogami, is nearly pure iron and carbon. Blue paper, Aogami, is the same base with tungsten and chromium added for wear resistance and easier heat treatment. There are three common grades: Aogami #2, Aogami #1 and, at the top, Aogami Super.

The steel is made by Proterial Ltd, the specialty-steel business that was Hitachi Metals until it was renamed in 2023. You will still see it written as Hitachi Blue Super on most retailer pages, which is why the name looks inconsistent across the internet.

Aogami Super composition and hardness

Aogami Super is Blue Steel with everything turned up. Typical published figures are roughly:

• Carbon 1.40-1.50% — the highest of the Aogami family, and what makes the extreme hardness possible
• Tungsten 2.00-2.50% — hard carbides for wear resistance
• Chromium 0.30-0.50% — for hardenability, not corrosion resistance
• Molybdenum 0.30-0.50% and Vanadium 0.30-0.50% — grain refinement and extra carbides
• Manganese 0.20-0.30%

Heat treated well it finishes at 63-65 HRC. That is at the very top of the kitchen range. For context, a good German knife sits near 56-58, most Japanese stainless kitchen steels land at 60-61, and our own Bara Forge blades are specified at 60 HRC. If the numbers are unfamiliar, the Rockwell hardness chart puts each value in order, and our guide to the best hardness rating for kitchen knives explains why higher is not automatically better.

The number that decides how the knife behaves day to day is not the carbon figure but the chromium one. Stainless begins at about 10.5% chromium. Aogami Super has roughly a twentieth of that. It is not a stainless steel, it is not a semi-stainless steel, and no amount of tungsten changes that.

Does Aogami Super rust?

Yes, and quickly, and this is the single most useful thing to know before buying one. Leave an Aogami Super blade wet on a board after cutting a lemon and you will see orange spotting within the hour. Cut an onion and leave it unwashed overnight and you will find etching in the steel where the juice sat.

What you get in exchange for that fragility is a patina: a stable grey-blue oxide layer that forms with use and then protects the steel underneath. A well-used Aogami Super blade is not shiny, and it is not meant to be. Patina is the steel doing its job. Rust is the steel being neglected. Our guide to carbon steel knife patina covers the difference, and how to care for a carbon steel knife covers the routine: wipe dry as you go, wash and dry immediately after use, and oil the blade before it goes away.

If reading that made you tired, that is a genuine answer to the buying question, not a failure of nerve. The same care applies to our own 1080 high-carbon Snažan Heritage Cleaver, which is why we say so on the product page rather than after the sale.

Why Aogami Super is almost always a clad blade

Look closely at Aogami Super knives and you will notice something the spec sheets rarely mention: you almost never see a mono-steel one. The blade is nearly always laminated, with a thin Aogami Super core sandwiched between softer stainless or iron cladding, often finished in the black kurouchi forge scale.

There are two reasons, and both matter to a buyer. At 63-65 HRC a whole blade of Aogami Super would be brittle enough to chip on a chicken bone or a hard squash. And a mono blade would be reactive over its entire surface rather than just at the edge, which would make the care routine genuinely punishing. Cladding solves both at once: the hard core does the cutting, the soft jacket takes the impact and the corrosion.

Which means that buying Aogami Super is really a san mai decision, and the honest comparison is not steel against steel but construction against construction. Our Kaiju series uses exactly that architecture with an SLD tool-steel core instead of a carbon one: the same three-layer logic, the same hard centre, and stainless cladding on both faces.

Aogami Super vs VG-10

VG-10 is the comparison most buyers are actually making, because VG-10 and its relatives sit in almost every Japanese kitchen knife on the western market.

• Edge retention: Aogami Super wins, and not by a small margin. The tungsten and vanadium carbides at 64 HRC hold a working edge far longer.
• Corrosion resistance: VG-10 wins outright. At around 15% chromium it forgives a wet blade on the drying rack. Aogami Super does not.
• Sharpening: Aogami Super is the easier of the two to bring back on a stone, which surprises people. Its carbides are tungsten and vanadium but its matrix is simple carbon steel, so it takes a keen edge fast. VG-10 is more stubborn and more prone to burr.
• Toughness: roughly a wash in practice, once cladding is accounted for.

The equivalent conversation on our side of the bench is AUS-10, the steel at the core of our Feather Forge blades and a close cousin of VG-10. Our VG-10 guide covers that family in detail. If you want the powder-metallurgy version of the same trade, SG2 buys most of the edge retention back while staying stainless — at a price, and with a harder sharpening job.

Is Aogami Super steel worth it?

It is worth it for one specific cook: someone who sharpens their own knives, dries them without being reminded, and cuts enough food that edge retention shows up as time saved rather than as a specification. For that person Aogami Super is one of the best steels money can buy, and the price premium is real value.

It is not worth it for a knife that lives in a dish rack, gets used twice a week, and goes back in a drawer damp. In that house an Aogami Super blade will be a worse knife than a stainless one costing a third as much, because it will spend most of its life dull and spotted. This is the part the shop pages do not say.

A fair middle path: keep a stainless workhorse for citrus and tomatoes and let a carbon blade do the dry work. That is how most professional kitchens using carbon steel actually run.

Who makes Aogami Super knives?

Aogami Super is a steel, not a brand, and Proterial sells it to smiths rather than to consumers. Most of it ends up with Japanese workshops in Sakai, Echizen and Tosa, whose blades reach western buyers through specialist retailers. Because the steel is sold on and the heat treatment is done by each smith, two knives with the same steel stamp can perform very differently. With carbon steel more than with stainless, the maker matters more than the label.

One PAA question that comes up alongside this deserves a straight answer: Anthony Bourdain's favourite knife was not an Aogami Super blade at all. He famously recommended the Global G-2, a stainless Japanese chef knife, on the grounds that one good knife you look after beats a block full. The steel in it is not exotic. The advice still holds.

What about Ginsan, Shirogami and the rest?

If Aogami Super appeals but the rust does not, Ginsan (also written Gin-San or Silver-3) is the usual answer: a stainless steel with carbon-steel sharpening behaviour, made by the same mill. Shirogami, white paper steel, is the purist's choice — the cleanest edge of all and the least forgiving. Aogami #2 is the sensible everyday member of the blue family, giving up some edge life for a little more toughness and a lower price.

For the full shape of the Japanese knife market, our Japanese chef knife guide covers how steel, shape and construction fit together, and sharpening a Japanese chef knife covers the angles and grits that any of these steels need.

Common questions

What HRC is Aogami Super? Typically 63-65 HRC after heat treatment, which is at the top of the kitchen-knife range and harder than almost anything stainless.

Is Aogami Super stainless? No. At roughly 0.3-0.5% chromium it is nowhere near the 10.5% threshold for stainless. Many Aogami Super knives have stainless cladding, but the edge itself is reactive carbon steel.

Is Aogami Super better than Shirogami? Different rather than better. Aogami Super holds an edge considerably longer; Shirogami takes a marginally finer edge and is easier to sharpen. Aogami Super is the more practical of the two for most cooks.

What is the best super steel for kitchen knives? For pure edge retention in a kitchen, Aogami Super and SG2 lead. For a cook who wants a very good edge without a care routine, a well heat-treated AUS-10 or VG-10 at 60-61 HRC is the better buy.

Shop the range

We do not forge on Aogami Super, but the same reasoning — hard core, sensible cladding, a published hardness and a blade you can actually sharpen — runs through everything we make. Every blade from The Cooking Guild is hand sharpened and oiled before it ships: the sharpest blades you will ever use, or your money back.

Start with a hand-forged chef knife, look at the laminated Japanese chef knives, or build out from a knife set. Every knife comes with a 99-day home trial and a free lifetime guarantee.

Keep reading: SG2 Steel · San Mai Steel · AUS-10 Steel · VG-10 Steel · D2 Steel · 440C Steel · Carbon Steel Knife Care · Rockwell Hardness Scale · How to Use a Whetstone