The tungsten-alloyed rarity of the Hitachi family, sharing White
Aogami
For the Newcomer
Aogami #1 (Blue Steel #1) is the direct alloyed evolution of Shirogami #1: it takes the same high-carbon base and adds A hard, dense metal added to steel; it forms very hard carbides that help a blade hold its edge longer. and a trace of chromium, giving it measurably better edge retention while preserving the fine edge refinement the Hitachi steels are known for. It is less commonly encountered than its sibling Aogami #2 and tends to command a premium. Like all Hitachi carbon steels, it is completely reactive. For serious knife users who find Blue #2 satisfying but want a modest step up in edge longevity, Blue #1 represents a compelling and somewhat scarce upgrade.
About this composition
The tungsten carbide advantage. Tungsten dissolves partially into the The hard crystal structure that forms when carbon steel is quenched; it gives the blade its hardness. at hardening temperatures and partially precipitates as fine W₂C particles, a form of An extremely hard compound of tungsten and carbon; it resists wear far better than the ordinary iron carbide found in plain carbon steel.. Tungsten carbide has a hardness of roughly 1700–1900 HV, more than double chromium carbide and far harder than cementite. These fine hard particles resist micro-abrasion at the edge apex more effectively than the Microscopic hard particles within steel that resist wear; large ones blunt the finest edge, so small, evenly spread ones are prized. population of White steels, translating to meaningfully longer-lasting edges.
The carbides stay small because total alloy loading is modest: you get wear resistance without the edge-refinement penalty of large carbides (as in D2 or high-vanadium PM steels).
Heat-treatment complexity. Tungsten dissolves slowly during austenitizing, requiring longer hold times than the White steels. Underdissolved tungsten means the steel doesn't capture the full alloy benefit. Skilled artisans are familiar with this, and it is one reason Blue #1 is less commonly offered by smaller production shops.
Yoshikazu Tanaka as the Blue #1 reference. Tanaka (Sakai) built his reputation specifically around Blue #1 gyutos at accessible prices: pine charcoal forge, traditional quench. The Hado Sakai line is the same Tanaka steel plus Nomura's polish work, the premium tier of the same lineage.
Performance Deep Dive
Edge retention: Noticeably longer than Blue #2, comparable to the AEB-L to VG-10 jump in the stainless world.
The W₂C carbide structure resists micro-abrasion meaningfully better than the White steels at comparable hardness.
Toughness: Slightly less than White #1 at equivalent HRC.
The extra alloy content adds modest brittleness. Still entirely usable in kitchen geometry.
Corrosion resistance: None, same as White steels.
Treat exactly like Shirogami #1 in the kitchen.
Ease of sharpening: Slightly more demanding than White steels, far easier than PM stainless.
Tungsten carbide presence requires more abrasive action but quality waterstones still cut readily. Modest effort.
- vs. Shirogami #1: Same carbon, plus tungsten; longer edge retention, slight sharpening tax.
- vs. Aogami #2: Same family; Blue #1 has more carbon and more tungsten, longer edge retention, rarer.
- vs. Aogami Super: Aogami Super adds V and Co; longer edge retention again but harder to sharpen.
Research Notes
Market reality. Blue #1 commands a modest premium over Blue #2 and is produced in smaller quantities. Many Sakai smiths who offer White #2 and Blue #2 do not offer Blue #1 as a separate line. Yoshikazu Tanaka and Hatsukokoro at Carbon Knife Co are the most consistently available Blue #1 specialists.
In the Kitchen
Blue #1 is the move when you want carbon-steel edge refinement and meaningful edge retention. Karaku at $125–$135 is the accessible entry point. Tanaka 180mm at $250 is the canonical artisan starter. Tanaka 210/240mm gyutos at $400–$450 are the workhorse picks. Hado Sakai and Naoki Mazaki are the premium-to-collector ceiling. Treat it like any reactive carbon blade: wipe, dry, and oil every session, and lean on the care section for the patina routine.
Composition
| Element | % | Role |
|---|---|---|
| Carbon (C) | 1.3 | Same high-carbon as Shirogami #1; supports maximum hardness potential (range 1.25–1.35) |
| Silicon (Si) | 0.15 | Minimal deoxidizer |
| Manganese (Mn) | 0.25 | Minimal hardenability |
| Chromium (Cr) | 0.35 | Slight corrosion improvement vs White steel (minimal practical effect); forms some Cr carbides (range 0.20–0.50) |
| Tungsten (W) | 1.25 | KEY: forms W₂C, fine and very hard carbides that resist edge wear; dramatically improves edge retention vs White #1 (range 1.00–1.50) |
Steel family: Alloy carbon steel (ingot-cast). Simple carbon steel base with tungsten plus minor chromium additions. The W₂C carbides are harder than cementite, providing meaningfully better wear resistance than the White steels while preserving fine carbide distribution. Not stainless.
Artisan Makers
| Maker | Knife | Style | Price | Link |
|---|---|---|---|---|
| Yoshikazu Tanaka | Blue #1 Gyuto 240mm | Sakai charcoal-forged; iron-clad kurouchi; benchmark Blue #1 specialist | $450 | chefknivestogo.com |
| Yoshikazu Tanaka | Blue #1 Gyuto 210mm | Tanaka's accessible mid-size Blue #1 | $400 | chefknivestogo.com |
| Yoshikazu Tanaka | Blue #1 Gyuto 180mm | Smaller Tanaka Blue #1; the most accessible Tanaka entry | $250 | chefknivestogo.com |
| Yoshikazu Tanaka / Hado Sakai | Sumi B1D Gyuto 240mm, Damascus clad, cherry bark handle | Hado Sakai = Tanaka steel plus Nomura polish; Damascus cladding, cherry-bark traditional handle | $992 | knifewear.com |
| Hatsukokoro | Yoake Blue #1 Kurouchi Gyuto 240mm | Sakai, kurouchi finish | $389 | carbonknifeco.com |
| Karaku / Michikuni Tokaji | Blue #1 Gyuto 240mm | Sakai; accessible entry into Blue #1 territory | $135 | chefknivestogo.com |
| Karaku / Michikuni Tokaji | Blue #1 Gyuto 210mm | Sakai entry-priced Blue #1 | $125 | chefknivestogo.com |
| Naoki Mazaki | Aoichi Beads Black Damascus Gyuto 240mm | Sakai collector piece; Damascus with bead pattern | $1,950 | knifewear.com |