Carbon steel · ProterialAogami #1 青紙1号
Also called: Blue #1 · Ao #1 · Blue paper steel #1
Aogami #1 is a non-stainless carbon steel from Proterial (formerly Hitachi Metals): 1.25–1.35% carbon, 0.30–0.50% chromium, and a maker hardening hardness of ≥60 HRC.
Composition
| C | Si | Mn | P | S | Cr | W |
|---|---|---|---|---|---|---|
| 1.25–1.35 | 0.10–0.20 | 0.20–0.30 | ≤0.025 | ≤0.004 | 0.30–0.50 | 1.50–2.00 |
Mass %. As published by the steelmaker (typical or representative values). Hardness: ≥60 (hardening hardness).
What the data says
Aogami #1 starts from the same 1.25–1.35% carbon as Shirogami #1 and adds 0.30–0.50% chromium and 1.50–2.00% tungsten. Proterial describes the Blue steels as alloy steel with tungsten and chromium added to improve heat-treatment properties and wear resistance.
Compared with Aogami #2, #1 has about 0.2% more carbon and roughly 0.5% more tungsten. Aogami Super goes further again, with more carbon and tungsten plus vanadium.
The small chromium addition does not make it stainless: at 0.30–0.50% it is far below the roughly 10.5% that defines a stainless steel, so it still needs to be kept dry.
Aogami #1 compared with similar steels
| Steel | Type | C % | Cr % | Maker HRC | CATRA mm |
|---|---|---|---|---|---|
| Aogami #1 | Carbon | 1.25–1.35 | 0.30–0.50 | ≥60 | — |
| Aogami #2 | Carbon | 1.05–1.15 | 0.20–0.50 | ≥60 | — |
| Aogami Super | Carbon | 1.40–1.50 | 0.30–0.50 | ≥60 | 338 @ 65.1 |
| Shirogami #1 | Carbon | 1.25–1.35 | — | ≥60 | — |
Detailed comparison: Blue vs White steel
See all 15 steels in the Japanese knife steel chart, or compare up to three at once in the steel explorer.
Care
Aogami #1 is not stainless. Wipe the blade dry after use; a grey or blue patina is normal, but orange spots are rust and should be removed early.
Buying a Aogami #1 knife from a shop in Japan? Japanese kitchen knives currently pay about 31% US import duty — use the import duty calculator to compare with a US retailer.
Frequently asked questions
- Is Aogami #1 stainless?
- No. Aogami #1 contains only 0.30–0.50% chromium, while a stainless steel needs roughly 10.5% or more, so it can rust if left wet.
- How hard is Aogami #1?
- Proterial publishes a hardening hardness of ≥60 HRC. The hardness of a finished knife depends on the knifemaker’s heat treatment.
- Who makes Aogami #1?
- Aogami #1 is made by Proterial (formerly Hitachi Metals).
- Aogami #1 vs Aogami #2: what is the difference?
- Aogami #1: C 1.25–1.35%, Cr 0.30–0.50%, maker hardness ≥60 HRC. Aogami #2: C 1.05–1.15%, Cr 0.20–0.50%, maker hardness ≥60 HRC.
Sources
Checked 2026-10-21. Found a better source or an error? Tell us.