Another steel produced by the Hitachi Steelworks, by casting, for knives and tools. It is usually hardened to 63-65 HRC. Due to the increased content of carbon, tungsten and the addition of other carbide-forming elements and (which also improve hardenability), such as vanadium and molybdenum, it achieves a hardness greater than Aogami 2. Similarly to the above steel, it is classified as the highest purity steel. It is often referred to as "carbon steel with an ideal composition for the production of knives." Japanese makers using this steel include TakeshiSaji, Moritaka and Takeda. Thanks to the precisely designed chemical composition, this steel holds the sharpest and the longest of all Aogami steels, at the same time it is easy to sharpen, with high abrasion resistance in everyday use. As for the cut, its extreme sharpness makes it silky smooth. Due to the low resistance to rusting and damage in the form of chipping (due to incredible hardness), this steel often serves as the core in laminated knives. It is then used with amphibians made of softer steel, often stainless, thus eliminating both of its shortcomings.
Composition:
- Carbon: 1,40 – 1,50%
- Tungsten: 2,00 – 2,50%
- Vanadium: 0,30 – 0,50%
- Chromium: 0,30 – 0,50%
- Molybdenum: 0,30 – 0,50%
- Manganese: 0,20 -0. 30%
- Silicon: 0,10 – 0,20%
- Phosphorus: 0,025%
- Sulfur: 0,004%