AUS-8 (often called AUS-8A) is a mid-range Japanese stainless steel produced by Aichi Steel Corporation. For years, it was the "gold standard" for high-quality, affordable folding knives and was the primary competitor to American 440C.
It is a well-balanced steel that is famous for its toughness and the ability to take an incredibly sharp edge.
Key Characteristics
Exceptional Sharpness: Due to its fine grain structure and the addition of Vanadium, AUS-8 can be sharpened to a "hair-popping" razor edge very easily.
Superior Toughness: It is much tougher and less brittle than higher-carbon steels like 154CM or D2. It can handle impacts and "hard use" without the edge chipping.
Balanced Edge Retention: It is typically hardened to 57–59 HRC. While it won't stay sharp as long as modern "super steels," it holds a working edge much better than the AUS-6 or 420 series.
Good Corrosion Resistance: It is a true stainless steel and handles moisture well, though it still requires basic cleaning to prevent spotting.
Chemical Composition
The "A" in AUS-8A refers to the steel being annealed, though the chemistry remains the same:
Carbon (C): 0.70% – 0.75% (Provides a good balance of hardness and toughness)
Chromium (Cr): 13.0% – 14.5% (Provides rust resistance)
Manganese (Mn): 0.50%
Vanadium (V): 0.10% – 0.26% (The "secret" to its fine grain and ease of sharpening)
Molybdenum (Mo): 0.10% – 0.30%
Common Applications
Tactical & EDC Folding Knives: A legendary choice for brands like Cold Steel (e.g., the SRK or Voyager), SOG, and Ontario Knife Company (the famous RAT-1 and RAT-2).
Outdoor Survival Knives: Valued because it is easy to sharpen in the field with a simple stone.
Boot Knives & Daggers: Where toughness is more important than long-term edge holding.
AUS-8 vs. 8Cr13MoV
In the knife world, these two are often compared. While their performance is very similar, AUS-8 is generally considered slightly superior because its grain structure is often finer (due to better Japanese manufacturing standards), making it a bit tougher and easier to get a "scary sharp" edge.