The apex of the Hitachi carbon family, with vanadium-refined carbides, cobalt-assisted hardening, and edge retention that makes other carbon steels jealous.
Aogami Super (Blue Super)
For the Newcomer
Aogami Super (Blue Super) is the most complex and highest-performing member of the Hitachi carbon steel family. It adds An alloying element that forms extremely small, very hard particles, giving a steel exceptional wear resistance without coarsening the edge. and cobalt to the Aogami base: vanadium for finer, harder Microscopic hard particles within steel that resist wear. Finer ones boost edge longevity without blunting the apex. (exceptional edge retention), cobalt to allow harder heat treatment outcomes. The result is a carbon steel that holds an edge significantly longer than Aogami #2 or Aogami #1, while still achieving the outstanding sharpness refinement the Hitachi family is known for. Like all Hitachi carbons, it is completely reactive. The sharpening experience is slightly more demanding than Shirogami #1 or Blue #2 (the vanadium carbides add some resistance), but it is still far easier than any PM stainless. If you want the best edge-retention performance from a carbon steel and you are willing to care for it properly, Aogami Super is the reference standard.
About this composition
Vanadium carbides, the key to AS's performance. The 0.30–0.50% vanadium is the most significant addition. The very hard particle that vanadium forms in steel; it is harder than tungsten or chromium carbides and stays fine, which is ideal for edge wear resistance. (VC) is harder (~2800 HV) than either W₂C (~1700–1900 HV) or Cr₂₃C₆ (~1300 HV). These very hard, fine particles provide exceptional abrasion resistance at the edge. They remain small because vanadium content is moderate, enough to improve performance measurably without the large clustered carbides that limit edge refinement (as in high-vanadium PM steels).
Cobalt note. Cobalt reduces toughness in knife steels per Larrin Thomas. Its value in AS is enabling higher The high-temperature step in heat treatment where the steel is held hot enough for carbides to dissolve before quenching. temperatures during heat treatment and thus better carbide dissolution, supporting the harder heat treatment that produces AS's high HRC outcomes. This is a legitimate engineering trade-off, not a fraud; claims that cobalt is intrinsically improving edge quality are marketing rather than metallurgy.
Moritaka at 65 HRC. Iron-clad kurouchi gyutos at $225–$255 with a 700+-year family lineage. Independent community verification places the 65 Rockwell C, the standard hardness scale for blade steel. Most kitchen knives fall between about 56 and 66. claim as credible. One of the most-discussed value propositions in the online Japanese knife community.
Shibata Kotetsu, the thin grinder. AS gyutos that are reportedly among the thinnest-ground production AS knives available; spine at the heel can measure below 2mm. Combined with ~63 HRC and AS's carbide structure, this represents a thinness-and-edge-retention combination very difficult to achieve in stainless.
Performance Deep Dive
Edge retention: Exceptional within the carbon-steel world, comparable to mid-range stainless.
Comparable to AEB-L or N690 in edge longevity but with a carbon steel's sharpening ease and refinement.
Toughness: Modestly reduced by cobalt addition.
Still fully kitchen-appropriate. Cobalt's slight toughness penalty matters at 65+ HRC, not at the more common 63 HRC.
Corrosion resistance: None; same care as White and Blue.
The 0.30–0.50% Cr is metallurgically meaningless for corrosion.
Ease of sharpening: Slightly more deliberate than Blue #2.
Vanadium carbides require more abrasive action; quality waterstones at 1000 grit cut adequately. Proper deburring and stropping is important, since the fine carbide population benefits from a clean final pass. Full technique is in the care section.
In the Kitchen
Aogami Super is the right choice when you want carbon-steel edge refinement and premium-stainless-class edge longevity. It pairs naturally with a gyuto or bunka profile from a maker who can take advantage of its hardness. Moritaka at $225–$255 is the community's value reference. Nigara at $249 is the underdog (northern Japan emergence). Shibata Kotetsu's thin grind is the performance specialist. Fujiwara Denka at $1,185 is the Western collector reference. Whatever you choose, expect the same reactive-steel commitment as the rest of the Hitachi family: it will develop A protective layer of stable black iron oxide that builds on carbon steel with use; a sign of a well-kept blade, not damage., and every session should end with an immediate dry-and-oil ritual.
Composition
| Element | % | Role |
|---|---|---|
| Carbon (C) | 1.45 | Very high; highest in the Hitachi family; enables maximum hardness potential (range 1.40–1.50) |
| Silicon (Si) | 0.15 | Minimal |
| Manganese (Mn) | 0.25 | Minimal |
| Chromium (Cr) | 0.4 | Slight contribution; still not stainless |
| Tungsten (W) | 2.25 | More W than either Aogami #1 or #2; significant W₂C carbide population (range 2.00–2.50) |
| Vanadium (V) | 0.4 | KEY: forms very fine VC; harder than W₂C; finest carbide-based wear resistance (range 0.30–0.50) |
| Cobalt (Co) | 2.25 | KEY: supports higher austenitizing temperatures during HT; enables higher achievable HRC. Also slightly reduces toughness, an engineering trade-off (range 2.00–2.50) |
Steel family: Highly alloyed ingot-cast carbon steel (approaching alloy-tool-steel complexity). Vanadium and cobalt distinguish it from all other Hitachi steels. Not stainless (Cr in solution far below threshold).
Artisan Makers
| Maker | Knife | Style | Price | Link |
|---|---|---|---|---|
| Moritaka Hamono | Aogami Super Gyuto 240mm | Yamaga, Kumamoto; iron-clad kurouchi compound/convex grind; 65 HRC; 700+-year family lineage | $255 | chefknivestogo.com |
| Moritaka Hamono | Aogami Super Gyuto 210mm | Same Moritaka construction, mid-size | $225 | chefknivestogo.com |
| Takayuki Shibata / Kotetsu | AS Gyuto 210mm | Echizen; among the thinnest-ground production AS knives (spine at heel below 2mm) | $250 | chefknivestogo.com |
| Shiro Kamo | Aogami Super Gyuto 240mm | Echizen, traditional craft | $220 | chefknivestogo.com |
| Nigara Hamono | AS Gyuto 210mm | Aomori (northern Japan, unusual region); quality AS at accessible price | $249 | tokushuknife.com |
| Nigara Hamono | AS Tsuchime Bunka 180mm | Aomori, bunka profile with hammered tsuchime finish | $244 | knifewear.com |
| Masakage Koishi / Yoshimi Kato | Koishi AS Gyuto 240mm | Takefu Village, Kato grind | $500 | knifewear.com |
| Hatsukokoro | Kurosagi AS Gyuto 240mm | Sakai, kurosagi (black heron) finish | $218 | knifewear.com |
| Teruyasu Fujiwara | Denka Gyuto 240mm | Tokyo-forged Fujiwara premium line, a collector reference for Aogami Super | $1,185 | knifewear.com |