Aogami #3 (Blue Paper Steel No. 3) is the lowest-carbon grade in the Blue Paper series produced by Hitachi Metals. While Aogami Super and Aogami #1 are designed for maximum hardness, Aogami #3 is engineered to prioritize toughness and stability.
It is much less common in high-end kitchen knives than Aogami #2, but it is highly valued for specific tools and heavy-duty applications.
Key Characteristics
The Toughest Blue Steel: Because it has the lowest carbon content in the family, it is the least brittle. It is significantly more resistant to chipping and cracking than Aogami #1 or Super, making it suitable for tools that might experience light impact.
Reliable Edge Retention: Even though it has less carbon, it still contains Tungsten and Chromium. This means it holds an edge longer than standard carbon steels (like 1095 or Shirogami #3), though it falls behind Aogami #2 in pure cutting longevity.
High Hardness: It is typically heat-treated to 58–60 HRC. While this is "low" for a Japanese carbon steel, it is still harder and stays sharp longer than most common Western stainless steels.
Exceptional Sharpness: It maintains the fine grain structure of the Blue Paper series, allowing it to take a very keen, aggressive edge that is easy to maintain on whetstones.
Non-Stainless (Reactive): Like all Blue steels, it will rust. It will develop a patina over time and requires immediate drying after use to prevent corrosion.
Chemical Composition
Carbon (C): 0.80% – 0.90% (Provides toughness and ease of sharpening).
Tungsten (W): 1.00% – 1.50% (Provides wear resistance).
Chromium (Cr): 0.20% – 0.50% (Adds stability and hardenability).
Manganese (Mn): 0.20% – 0.30%
Common Applications
Heavy-Duty Japanese Tools: Used for traditional Japanese hatchets (Nata), woodcarving tools, and outdoor utility knives where the blade needs to be tough enough to handle wood without chipping.
Entry-Level Japanese Knives: Sometimes found in affordable hand-forged kitchen knives where durability is prioritized for home users.
Traditional Folding Knives: Used in some variations of the Higonokami or other task-specific folders.
The Aogami Family Comparison
Grade | Carbon Content | Hardness (HRC) | Primary Strength |
|---|---|---|---|
Aogami Super | 1.40% – 1.50% | 63–65 | Ultimate Edge Retention |
Aogami #1 | 1.25% – 1.35% | 62–64 | High Hardness / Edge Life |
Aogami #2 | 1.05% – 1.15% | 61–63 | Balanced Professional Choice |
Aogami #3 | 0.80% – 0.90% | 58–60 | Maximum Toughness / Stability |