Blue Steel #2 (Aogami #2)
Traditional Japanese carbon steel with tungsten and chromium, valued for its fine edge, high hardness, good wear resistance and easy edge restoration on sharpening stones.
Blue Steel #2, in Japanese Aogami #2 or Aogami 2, is one of the well-known Yasugi Specialty Steels used for high-quality kitchen knives and other cutting tools. It is based on clean carbon steel with the addition of mainly tungsten and chromium.
These alloying elements improve properties during heat treatment and increase the steel’s wear resistance. Aogami #2 can therefore form a very fine edge and, when properly processed, retain it for a long time. At the same time, it remains easy to sharpen on water sharpening stones.
Blue Steel #2, however, is not stainless steel. Its low chromium content is insufficient to create the corrosion resistance typical of stainless materials. The blade should be wiped during use, washed by hand after use and dried thoroughly immediately.
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Very fine edge
The high carbon content allows a precise edge suitable for clean kitchen cuts.
Good edge retention
Tungsten and chromium contribute to wear resistance and the stability of a properly processed edge.
Pleasant sharpening
Aogami #2 responds well to quality water sharpening stones and allows precise edge restoration.
Traditional character
The steel can develop a patina that changes with use and gives every knife an individual appearance.
Chemical composition of Aogami #2
The following ranges represent the typical chemical composition stated by Proterial, manufacturer of Yasugi Specialty Steel. Actual values of a specific production batch may vary within the specified ranges.
| Element | Typical content | Role in the steel |
|---|---|---|
| Carbon – C | 1.05–1.15% | Basis for high hardness and the ability to form a fine edge. |
| Tungsten – W | 1.00–1.50% | Contributes to wear resistance and material stability. |
| Chromium – Cr | 0.20–0.50% | Improves hardenability and wear resistance, but does not make the steel stainless. |
| Manganese – Mn | 0.20–0.30% | Contributes to the properties of the steel during production and heat treatment. |
| Silicon – Si | 0.10–0.20% | A common accompanying component affecting material processing. |
| Phosphorus and sulfur | P ≤ 0.025%, S ≤ 0.004% | Undesirable impurities kept at a low level. |
Steel composition does not determine the performance of the whole knife
Final properties are also influenced by heat treatment, achieved hardness, blade geometry, thickness behind the edge, quality of the grind and the way the knife is used. Two Aogami #2 knives therefore do not necessarily cut or hold an edge exactly the same way.
Why is it called Blue Steel?
The name Aogami consists of the Japanese words for blue colour and paper. The term Blue Paper Steel does not describe the colour of the blade itself. It refers to colour coding of the steel that made it easy to distinguish between different material grades.
The blade itself is therefore not blue. Depending on the construction of the particular knife, its surface may be polished, matte, forged, blackened or clad with another steel.
Blue Steel #2, Aogami #1 and Aogami Super
The term “Blue Steel” is not the name of one universal steel. The Aogami family includes several different materials. When choosing a knife, always check the exact steel designation of the specific model.
| Steel | Basic character | Practical note |
|---|---|---|
| Aogami #2 | 1.05–1.15% carbon, tungsten and chromium | A balanced traditional choice with good edge retention and pleasant sharpening. |
| Aogami #1 | Higher carbon content than Aogami #2 | May allow higher hardness, but actual performance depends on how the knife is processed. |
| Aogami Super | Alloy steel with tungsten, chromium and vanadium | It is a separate steel; Aogami Super is not a synonym for Aogami #2. |
| Shirogami | Cleaner carbon steel without tungsten and chromium | Offers a very fine edge and easy sharpening, but behaves differently during heat treatment and wear. |
Aogami #2 is not Aogami Super or Ginsanko
Aogami Super has a different chemical composition and Ginsanko is stainless steel. If a knife made from Aogami Super or Ginsanko also appears in the listing, verify the exact material in the specifications of the specific product.
How hard is Aogami #2?
The steel manufacturer states a hardness exceeding 60 HRC after hardening. Finished kitchen knives often have values of around 60–63 HRC, but there is no single automatic hardness that applies to all manufacturers.
For example, for Kanetsune knives from the MUKASHI-NAGARANO series, the manufacturer states a hardness of 61–62 HRC. A bladesmith may choose a different heat treatment depending on the knife’s construction, geometry and intended use.
Blade construction determines maintenance requirements
Aogami #2 and soft iron
A traditional construction with soft iron sides is reactive over a large part of the blade. Patina may form on both the cutting core and the outer layers, and the knife requires careful drying.
Aogami #2 with stainless cladding
Stainless sides make most of the blade easier to care for. However, the exposed carbon core around the edge can still react with food and corrode.
Selected knives in Blue Steel #2
MUKASHI-NAGARANO
Hand-forged Kanetsune knives with a traditional Aogami #2 core and various blade finishes.
Nakiri KC-449 INAKA
Nakiri KC-447 HAMATOGI
Santoku KC-446 HAMATOGI
Nakiri KC-423 KODAI
Santoku KC-422 KODAI
Kanetsune YH-3000
Series with a carbon steel cutting core and SUS410 stainless cladding for easier care of the blade sides.
View knives in the Blue Steel category
Who is Aogami #2 suitable for?
| Aogami #2 is suitable if… | Consider stainless steel if… |
|---|---|
| you want a very fine and precise edge, | you often leave the knife wet or dirty, |
| you are willing to clean and dry the knife immediately, | you want the least demanding everyday maintenance possible, |
| you sharpen on stones or want to learn how, | the knife is shared by several users without certainty of correct handling, |
| you appreciate traditional material and natural patina. | you do not want to deal with patina or protection of the cutting core. |
Marek's tip
I would recommend Aogami #2 to a customer who wants a traditional Japanese edge and does not mind giving the knife a few extra seconds of care. If you wipe the knife during use and dry it immediately after washing, it rewards you with a very pleasant cut and easy edge restoration on stones.
Care for an Aogami #2 knife
- Wash it by hand only. A dishwasher may damage the blade, edge and handle.
- Wipe the blade regularly. Especially when cutting onions, tomatoes, citrus fruits and other acidic ingredients.
- Dry immediately after washing. Do not leave the knife to drip-dry or lie in the sink.
- Use protective oil for longer storage. A very thin layer of oil suitable for kitchen tools is enough.
- Protect the fine edge. Do not cut bones, frozen foods or hard pits.
- Use a suitable cutting board. Wood or high-quality plastic is ideal, not glass, stone or ceramic.
Sharpening Blue Steel #2
Aogami #2 sharpens well on water sharpening stones. For normal restoration of an undamaged edge, a medium grit of around 1000 is suitable. A finer stone can then be used to smooth and finish the edge according to the type of knife and desired result.
Avoid coarse pull-through sharpeners and excessive pressure. With single-bevel Japanese knives, their original geometry must be preserved.
Need advice?
Contact us by phone at +420 702 049 048, Monday to Friday between 7:30 and 16:00, or by email at info@dellinger.cz.
Frequently asked questions about Blue Steel #2
What is Blue Steel #2?
Blue Steel #2, or Aogami #2, is a Japanese high-carbon alloy steel with added tungsten and chromium, used for kitchen knives and other cutting tools.
Is Aogami #2 stainless?
No. The chromium content is too low for stainless steel. The blade may develop a patina and can corrode if not properly maintained.
What is the composition of Aogami #2?
It typically contains 1.05–1.15% carbon, 1.00–1.50% tungsten, 0.20–0.50% chromium and smaller amounts of manganese and silicon.
How hard is Aogami #2?
The steel manufacturer states more than 60 HRC after hardening. The exact hardness of the finished knife is determined by its manufacturer according to heat treatment and intended use.
Is Aogami #2 the same as Aogami Super?
No. Aogami Super is a separate steel with a different chemical composition that also includes vanadium.
Why is it called Blue Steel?
The name is related to the blue colour coding of the material, not the colour of the finished blade.
Is patina on Aogami #2 normal?
Yes. Grey, blue or rainbow colouring may be a natural patina. Active orange, powdery rust should however be removed.
How should a Blue Steel #2 knife be cleaned?
Wash the knife by hand, do not leave it in water and dry the blade thoroughly immediately after every use.
How should Aogami #2 be sharpened?
Quality water sharpening stones are the best choice. For normal edge restoration, you can start at around 1000 grit and then finish the edge more finely.
Is Aogami #2 suitable for a beginner?
Yes, if the user is prepared to clean the knife properly, dry it immediately and avoid bones, frozen foods and hard surfaces.
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The name "Blue Steel" (Aogami) – meaning "blue steel" – comes, as does "White Steel" (Shirogami), from the traditional Japanese packaging system used by Hitachi Metals.
Why "blue"?
Aogami steel was wrapped in blue paper when shipped from the steelworks (unlike white steel, which was wrapped in white paper).
This blue paper indicated that it was not pure carbon steel, but an improved version – White Steel enriched with alloying elements such as chromium and tungsten.
The name therefore has nothing to do with the color of the steel itself, but exclusively with the color of the original packaging and the type of steel inside.
What does "Aogami" mean?
青紙鋼 (Aogami-kō) literally means "blue paper steel":
青 (ao) = blue
紙 (gami/kami) = paper
鋼 (kō) = steel
The Blue Steel (Aogami) designation means:
Higher alloy grade than Shirogami (White Steel)
Wrapped in blue paper – a historical metallurgical standard
Combines the performance of traditional materials with modern improvements for greater durability and edge retention