A 2mm thick "Shiro 2" white carbon steel core (C 0.95-1.0, Cr 0.2-0.5, Ni 0.7-1.3) with eleven alternating layers of soft and hard steel on either side. The inclusion of Nickel and Chromium in the core layer broaden the temperature range in which a Martensitic structure is produced after quenching. This makes it easier to produce a really good blade when hand forging.
To maintain the purity of the steel and minimise carbon diffusion use a charcoal forge if possible. Forge at 800-900 Celsius. After forging and grinding, cycle at 750-800 Celsius to release any tension from the forging process, harden at 800 Celsius and quench in oil or water for 20 seconds, remove from the quench and allow to finish cooling more slowly, dabbing the back of the blade on a balled up wet rag.
Temper at between 150 and 250 Celsius to relieve the hardness to between RC64 and RC59 respectively.
330mm x 33mm x 5.5mm Unhardened Billet