Steel with this composition was frequently used in Japanese swords (Katana). The high carbon core layer does only extend to the middle of the blade’s profile. Multiple layers of softer steel folded on either side make this metal virtually unbreakable with excellent cutting properties. This type of construction also minimizes the risk of cracking during hardening. Usually the steel is forged further, but a blade can also be ground from the steel directly.

The material is supplied unhardened; instructions for heat treatment included (final hardness 62 Rockwell).

Not rust-proof.