Bainite is a structure of high-carbon steel that combines great strength with excellent flexibility and shock absorption characteristics. It has been known as an exemplary Katana blade component for a number of years but its use has been restricted to a few top-class master smiths, due to the difficulties involved in performing the exacting heat treatment procedures necessary for the production of a Bainite blade body in combination with the very hard Martensite Yakiba (edge section) required for Katana blades.
| Carbon | 0.65 ~ 0.75% |
| Chromium | 0.6 ~ 1.2% |
| Manganese | 0.25 ~ 0.8% |
| Molybdenum | 0.5% max |
| Nickel | 1.25 ~ 2.00% |
| Vanadium | 0.20 ~ 0.30% |
Hanwei has now mastered this difficult process, using billets of L-6 tool steel (a very tough high-carbon low-alloy steel) as a starting point. Blades are forged and shaped in the normal way, then carefully heat treated to achieve the required Bainite and Martensite structures before final polishing.