C75 steel is a carbon structural steel suitable as a dark component for damasks.

Unhardened, well hardened spring steel, supplied in annealed condition.

With a carbon content of 0.75%, 1.1248 steel is a commonly used alloy for springs and cutting tools.

It is very often used for making blades for Nordic knives, even by renowned makers, and as a dark component in damasks.
It is ideally combined with a light component in the form of nickel steel 75Ni8

Because it is not as hard (approx. 53 HRC) after hardening, it is very easy to grind to a high cutting edge. Nevertheless, it is durable and a properly sharpened blade cuts very well.

However, the steel is easily corroded and even with proper care, the blade will eventually acquire a patina like other "spring" steels.

Hardening:

The steel is heated to quenching temperature (usually 800-850°C) and then cooled rapidly in oil. After quenching, tempering is carried out to reduce internal stresses and increase toughness. The blade is heated to 400-630 degrees to achieve a hardness of 52-55 HRC.