steel grades

For a metal to be called steel, it must contain two essential elements: iron and carbon. However, the real difference lies in the additional alloying components. To classify knife steel more precisely, we divide it into two main categories:

Carbon steel : This steel contains between 0.04% and 2.14% carbon.
Stainless steel : To be classified as such, it must contain at least 11.2% chromium.

When choosing the right knife steel, you are often faced with the decision of whether you want to focus on edge retention and sharpness or on a lower susceptibility to rust .

On this page I would like to introduce you to the most commonly used types of steel.

Carbon steel:

Carbon knife steel (also called carbon steel or paper steel) is mainly produced by Hitachi in Japan. The most well-known variants are blue paper steel, also called Aogami , and white paper steel, known as Shirogami .

Worth knowing : The color names do not refer to the actual color of the steel, but to the paper in which the steel is packaged at Hitachi to distinguish it.

Carbon steel is particularly hard - harder than the usual knife steel that you may know from your own kitchen. This hardness makes it possible to sharpen the knife extremely sharply and to maintain this sharpness for a long time. On the other hand, however, the susceptibility to rust formation increases because it lacks chromium. However, with the right care and handling, this should not be a problem.

Shirogami:

White paper steel is one of the purest carbon steels. Shirogami is made from satetsu , an iron sand mined in Japan. This material has been used for centuries to make sword blades.

Compared to Aogami and other carbon steels, Shirogami is more difficult to work with. The blacksmith has a very small temperature window for hardening, so experienced and skilled hands are required to forge the steel flawlessly. If the steel is cooled too quickly, cracks can appear in the blade.

One advantage of Shirogami #2 is that it can be resharpened easily and effectively.

Shirogami comes in three quality levels: 1 , 2 and 3 , with quality 1 being the highest.

Aogami:

Blue paper steel, also known as Aogami , is very popular among Japanese knife makers because it is much easier to work with than white paper steel. However, it does not have the same purity. The difference is that Aogami contains a small amount of tungsten and chromium , which makes it more resistant to rust and wear. These additives make it possible to cool the steel with oil instead of water.

There are three common variants of Aogami: Blue #1 , Blue #2 and Aogami Super (also called Super Blue ).

Numbers #1 and #2 are the most common, with #2 being particularly popular as it offers an excellent combination of edge retention and durability .

Aogami Super also contains vanadium and molybdenum , which makes the steel even harder than the other two. This significantly improves both the edge retention and the achievable sharpness.

Other carbon steels:

Another popular steel for knife making is SK Carbon . Outside Japan, this steel is often overlooked or has a lesser reputation because it was originally considered a simple tool steel. Nevertheless, SK Carbon offers a hardness of 61 HRC , is extremely durable and offers a good service life - and all at a comparatively low price. Professionals particularly appreciate the quick and easy resharpening of this steel.

Rust carrier steel/stainless steel:

Rust-resistant or rust-free does not necessarily mean that a knife cannot rust . However, the high chromium content ensures that the steel is very resistant to rust. So with normal use you don't have to worry about rust. The downside of the high chromium content is that the steel is less hard , which leads to less sharpness and durability .

Nevertheless, this steel is particularly suitable for use in professional kitchens, as there is often not enough time to constantly look after the knives. In addition, this steel offers excellent resharpening properties due to its lower hardness.

Ginsan / Gin3:

Ginsan , also known as silver paper steel or simply silver , is also manufactured by Hitachi. It is the only stainless steel produced there. Its composition is similar to other carbon steels, but it contains a very high proportion of chromium . Ginsan is particularly popular with the blacksmiths in Sakai and Tosa , where it is hardened to between 60 and 63 HRC .

Ginsan is a fine grain, high carbon stainless steel . In my opinion, it is one of the most underrated knife steels. When heat treated well, it delivers performance well above its price point. Ginsan is a dream to sharpen and offers similar cutting strength to Blue #2 , but without the typical stresses that can occur with other steels due to its high stainless properties .

VG10:

The most widely used rust-resistant knife steel in Japan is VG10 . This steel is manufactured in Takefu , Japan, and has an average hardness of 60-61 HRC , despite the higher chromium content . This hardness is achieved by the special development of the steel for the production of kitchen knives . VG10 is particularly popular due to its ease of use and high resistance . So if you are looking for a real, high-quality all-rounder , this steel is an excellent choice.

AUS 8 / 10

AUS steel is a very tough steel manufactured by Aichi Steel . The average hardness of AUS8 is HRC 59 , while AUS10 is slightly harder at around HRC 61 .

Knives made from this steel are in the mid-price range and are an excellent introduction to the world of Japanese knives. They are easy to resharpen and are generally relatively easy to care for.

In general, it can be said that an AUS knife achieves the perfect balance between toughness , hardness , edge retention , wear resistance and corrosion resistance .

SG2 / R2

SG2 is one of the so-called powder steels and has now become a real crowd favorite, especially thanks to its excellent properties.

For many manufacturers, such as Takamura Hamono , SG2 is the ideal material for blade production. The fine grain structure enables excellent formation of the cutting edge. The steel achieves an average hardness of 63 HRC , which makes it as hard and sharp as paper steel , but retains the rust-proof advantages of stainless steels .

SG2 requires a little more effort to resharpen , but holds its sharpness exceptionally long and the knife can become extremely sharp.

SLD

SLD Semi Stainless Steel was originally developed by Hitachi to cut other steels.

This steel stays sharp just as long as carbon steel, but is much easier to maintain and less prone to damage. However, SLD is not 100% rust-proof, so it should still be cleaned and dried after use.

SRS

SRS is a rust-proof, hard powder steel that offers exceptionally long edge retention . Powder steels in general are known for their outstanding edge retention and easy maintenance .

Why do I recommend SRS steel? It offers excellent performance , is easy to maintain and offers very good value for money .

There are of course many other types of steel used in knife making. Each has its own specific properties and advantages that make it particularly suitable for certain applications. However, the steels presented here are among the most common and well-known, as they are used particularly often in practice and offer a good balance of sharpness, durability and ease of care. However, depending on your needs and area of application, there are numerous other interesting types of steel that can also deliver excellent results.