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About Japanese steel

Since medieval times, the Japanese steel was made famous by samurai's katana (japanese sword) , although it is a very useful material in daily life. Now Including kitchen knives, Japanese steel is processed into many products and has been exported to all over the world.


The quality of Japanese steel depends on... Type of steel and its processes.


Types of Japanese Steel

Steel is what added carbon to iron.
Iron + carbon = steel

Iron is the most familiar metal for mankind and it is used in various places. Steel is made harder by adding carbon to iron.

Steel and iron are classified by carbon content.
  • Iron: containing 0 - 0.04% of carbon
  • Steel: containing 0.04 - 2.1% of carbon

Also steels can be classified into several types.
  • Carbon Steel : Traditionally recognized as a good material for kitchen knives. This steel is very sharp but easily oxidized, so it needs good maintenance after each use. The Japanese restaurant chefs prefer this type knives, as they do not neglect their maintenance. Now, most of the carbon steel is made by Hitachi Metals Ltd.

  • Stainless Steel : This is not as hard as carbon steel, but with the advantage that it is not easily oxidized, so that it does not need much maintenance. Increasing the proportion of chromium and prevent the oxidation. If proportion of chromium is greater than 13% is considered as a stainless steel.

  • High Carbon Stainless Steel : This is new type steel that has the advantage of carbon steel and stainless steel. Hard like carbon steel and prevent the oxidation like Stainless Steel. Many high grade kitchen knives are made of this steel.


These are the main brands of Japanese Steel.

  1. Carbon Steel

    Name

    Characteristic

    Aogami steel By Hitachi Metals Ltd. Aogami means "blue" , but this name has no relation to the color of steel. Very hard and highest quality carbon steel. The kitchen knife made of this steel is very sharp, but it is rusty so good maintenance is necessary. HRC Approx.63
    Shirogami steel By Hitachi Metals Ltd. its kitchen knife is very sharp and easy to sharpen. It is best material for Traditional style Japanese knife like Yanagiba , Deba. It is rusty so good maintenance is necessary. HRC Approx.62
    Kiigami steel Same series as Aogami and Shirogami steel, but the grade is a little low. HRC Approx.60
    Tamahagane Steel Tamahagane is the Steel for Japanese swords. Only Japanese swords manufacturers can obtain it. There are kitchen knives with name of Tamahagane, but that is not real. just using this name.
    It has been used principally for traditional shape knives, such as Deba and Yanagiba.
    Carbon Steel japanese traditional knife
    (Deba knife)
    Carbon Steel japanese knife
    (Yanagiba knife)


  2. Stainless Steel

    Name

    Characteristic

    Molybdenum steel Most popular used in Japanese stainless steel knives. It is also used for surgical scalpels. HRC Approx.59
    Gingami-3 Stainless steel by Hitachi Metals Ltd. It is used for razors and kitchen knife. HRC Approx.60
    Swedish Steel About 100 years ago, From Meiji era has been used frequently in Japanese cutlery. Especially Sandvik 19C27 is famous for its high quality. HRC Approx.60
    Most Japanese knives, especially Japanese western style knife are made of these materials.
    Stainless Steel santoku knife

    Stainless Steel japanese knife
    (Santoku knife made of Stainless Steel)

  3. High carbon Stainless Steel

    Name

    Characteristic

    VG10 Steel Made by Takefu tokushu steel Co. Very hard like carbon steel, and is resistant to oxidation. It is mainly used for high class knives such as Damascus kitchen knife. Chromium 15% ,  HRC Approx.61
    VG5 steel Made by Takefu tokushu steel Co. It has characteristics close to VG 10, but it is not as hard as VG 10. HRC Approx.59
    10A Steel Made by Aichi steel. It has characteristics very close to VG 10, but no exact data of component. HRC Approx.61
    Powdered High Speed Steel Steel made in USA, it is often used for high-class Japanese kitchen knife. There are cases that chipping or rust, but usually very hard.


  4. Damascus Steel
    Damascus is not the name of steel. For example, Blade of damascus knife is made by overlaying several kinds of steel. This blade (steel) is called damascus steel. The most important thing in quality is the core(cutting edge) material. And there are various effects by overlaying the steels.
    Knife blade made of japanese steel

  5. Warikomi Steel
    Warikomi is not the name of steel. It is the steel that sandwiched core material from both sides with other type of steel. By this technology is possible to make a higher quality knife at low prices.
    knife blade made of warikomi steel



Processes


Various processes are required to commercialize steel. For example, to make a kitchen knife requires more than 20 processes. And the most important process in determining the quality of steel would be heat treatment. Steel will be best condition by heating(hardening and tempering).



Best japanese steel


Finally, we think that the best steel is Damascus steel with VG10 Core.

Cross section of Damascus steel
(Cross section of Damascus steel with VG10 steel Core)

On the next page , you can see why Damascus steel with Core VG10 steel es the best.