The chart above is an approximate performance.

In addition to this graph, the performance will vary greatly depending on the shape of the blade and the heat treatment process.


Corrosion resistance
 

Corrosion resistance has a direct effect on the cutting edge of a blade.
Even if the rust is not visible to the naked eye, if rust appears on the edge, it will reduce the blade's sharpness.
For knives that are prone to rust, such as carbon steel knives, we recommend wiping off any moisture thoroughly after use or stropping with a leather strop.

As shown in the graph above, the effective corrosion resistance in a saltwater environment is such that if the knife has a rating of 7 or higher, the difference in corrosion resistance will be almost imperceptible, and rust that leads to pitting will not occur for around 8 hours.
Even if rust does occur, it can be wiped off without any damage by simply wiping it dry with a towel.

Toughness

When steel is impacted, small cracks enter from the inside, and it may be chipped or broken. This resistance to chipping, in other words, tenacity, is toughness.

High toughness does not mean high strength.Without a certain degree of hardness, deformation such as bending of the cutting edge will occur.

Subjectively, if it has a hardness of 60 HRC or more and high toughness, it can be said to be a high-strength knife.


Wear resistance

The durability of sharpness due to wear resistance is directly linked to hardness. However, wear resistance varies depending on the characteristics of the steel, even with the same hardness and edge angle. This depends on the elemental composition that makes up the steel, the carbonization of elements due to the carbon ratio, the fineness of the structure, etc.

A typical example is the high-performance powder steel M390, which has such a fine structure that it is touted as MicroClean, and has excellent wear resistance despite its hardness of 61HRC.
Furthermore, such a fine structure also affects excellent sharpness.
​However, when the objects being cut include hard objects, toughness is also required in addition to wear resistance.

​Steel