The Queen of the steels – Aogami Blue Super (Hitachi Metals Ltd.) is one of the greatest Japanese Carbon Steels. In addition to containing more Carbon, Chromium and Tungsten than Blue Steel No.1, it also includes Molybdenum. It has a very good edge sharpness and excellent edge retention, but is also capable of attaining high hardness without being brittle. Consequently, many knife enthusiasts rate Aogami Super as one of the very best High Carbon Steels in the world.

White, Yellow, Blue & Super Blue

steel types knives japanese aogami shirogami kigami yasugiJapanese steels are commonly known by the colour that the label wrapped around the steel happens to be (white, blue, super blue). In this case its super blue steel, also known as Aogami Super Blue. This is considered to be just about the best mix found for a high carbon steel for knife making. Carbon steels can deliver amazing levels of sharpness and Super Blue is considered to be about as good as it can get – it’s extremely easy to sharpen and giving a silky, smooth cut that we’ve all crave for in the kitchen.

The Moritaka range and Yoshihiro have an exceptionally hard Super Blue Steel cutting edge and are laminated in Stainless.

The downsides?

In the quest for the “perfect knife steel” (hint: there is none) there are always compromises. In the case of Super Blue there are a few to consider. When applied too much strength in single point, it can chip which is why it is often hammered in a softer stainless steel to give it more support. Knives made from it are built for their cutting ability not for showcase of power, so ensure you are buying it for the right reasons.

As it’s a high carbon knife, it will discolour and take a patina through use as it oxidises. Bear it mind that it does not effect the performance of the knife but not everyone likes this. We see it as the knife taking on a unique character all of its own, creating a history with its owner, so fair to say we like it. Again, this is why it is often laminated in stainless steel to protect the cutting edge.

There are other unseen compromises too, Super Blue steel is difficult to work with also for the blacksmith. This leads to more ruined or unusable blades which pushes up the cost of those blades that are finally finished. This contributes for the increased cost of these blades.

Summing up, it’s about as good as carbon steels get – it allows for an insanely sharp edge, but need some attention to ensure you keep getting the most out of that edge. For a more robust/forgiving carbon steel take a look at White Carbon Steel (Shirogami).

No more words than needed – today we’re presenting you a quick cheat sheet to steel qualities of kitchen (and not only) knives and a chart showing steel’s relation between hardness, price, durability and a grade. Enjoy!

Quick Cheat Sheet

SymbolFeatures / Applications
Shirogami 1Carbon steel with minimum impurities. Highest hardness / Highest quality tipped tool, Plane, Chisel, Razor
Shirogami 2Carbon steel with minimum impurities. High hardness / High quality tipped tool, Chisel, Razor, Sickle, Ax, Graver
Shirogami 3Carbon steel with minimum impurities. Middle hardness / Chisel, Sickle, Ax, Plane, Graver, Kitchen knife, Saw
Shirogami NokozaiCarbon steel with minimum impurities. / Highest quality Saw, Chisel
Kigami 2Carbon steel with minimum impurities. High hardness / High quality tipped tool, Chisel, Razor, Sickle, Ax, Graver
Aogami 1Alloy steel with W and Cr, to improve heat-treatment properties and wear resistance. / Highest quality Plane, other tipped tool, Razor, Kitchen knife
Aogami 2Alloy steel with W and Cr, to improve heat-treatment properties and wear resistance. / High quality Plane, other tipped tool, Kitchen knife, Sickle
Aogami SuperAlloy steel with W, Cr, V, to improve heat-treatment properties and wear resistance. / High quality Plane, other tipped tool, Kitchen knife, Sickle
KKAlloy steel with Cr, to improve heat-treatment properties and wear resistance. / Various Highest quality Kitchen knife, Razor blade
GIN 1High Cr stainless steel with Mo, to improve corrosion resistance. / Various Kitchen knife, Scissors
GIN 3Stainless steel which has hardness and sharpness comparable to carbon steel. / Various Kitchen knife, Scissors
GIN 5Stainless steel for the razor blade replacement. / Various Kitchen knife, Saw, Razor blade
ATS 34Popular Stainless blade steel. / Custom knife, High quality cutlery tool
ZDP 189Stainless blade steel made by powder metallurgy process. / Custom knife, High quality cutlery tool

 

Carbon Steel

General features of carbon steel make it perfect for Japanese blacksmiths as this steel is often used for Traditional Japanese knives. The only downside is that it’s not rustproof so a higher maintenance skills are needed.
The Japanese company Hitachi Metals makes special cutting steels which represent the highest global standard and are used for almost all the knives we offer. These Yasugi Special Steels , named after their place of origin, are produced from iron sand, the same material that was used to make the legendary Samurai swords. They have a highly pure structure and thus offer the best achievable sharpness for cutting.

Example of Yasugi knife:

Yoshihiro Yamawaki Kurouchi Nakiri 165mm Yasugi Steel

Blue Paper Steel (Aogami)
High carbon steel is specifically developed for tools and knives. This one has highest wear resistance and lowest toughness. Very good steel and a very popular choice for high end Japanese kitchen knives. A lot of Japanese custom makers use it. Easy to sharpen, even high hardness. Edge holding is just outstanding. Original Japanese knives made from these materials are treated with non-corrosive, food-safe oils (e.g. camellia oil) to prevent oxidation.

White Paper Steel (Shirogami)
Identical to Blue Paper Steel (Aogami) , except for the absence of Cr and W. It’s very pure carbon steel. Very popular knife steel for high end Japanese cutlery and especially with Honyaki type blades.
Very good edge holding, very high working hardness. This means you can grind it to exceptional sharpness, which retains it for a long time. These blades are particularly suitable for the gentle preparation of foods – but they are prone to oxidation, which means your knife will rust if not taken care of (Check our guide on 3 main maintenance sins).

Yellow Paper Steel (Kigami)
Better steel compared to SK series, but worse than both, Aogami and Shirogami. Used in high end tools and low/mid class kitchen knives.

SK Steel series
Solid performer as a cutlery steel. Low grade steel, mainly due to impurities. Used mainly in hand tools like axes, hammers and cheap kitchen knives.

(No example, we don’t sell low quality knives (: )

Japanese Steel (Nihonko, Hagane, Virgin Carbon Steel)
Important steel that has been used to produce knives in Japan since ancient times, providing better sharpness than common stainless steel. The Japanese steel is a premium grade of steel that boasts extremely high carbon content. It is manufactured in limited quantities in Japan. The steel is harder than German steel and has a greater sharpening potential. It also maintains an edge longer than other lower-carbon steel formulae. These features make Japanese steel the ideal material for manufacturing high performance cutlery.

 

Stainless Steel

Stainless steel is an alloy of iron, approximately 10~15% chromium, possibly nickel, and molybdenum, with only a small amount of carbon. Good Stainless steel blade kitchen knives make good rust resistance, easy maintenance, good sharpness, edge retention and ease of re-sharpening. Therefore, they have become more and more popular among beginning users to professional users in this generation.

High Carbon Stainless Steel normally refers to a higher-grade, stainless steel alloys with a certain amount of carbon, and is intended to combine the best attributes of carbon steel and ordinary stainless steel. The high carbon stainless steel blades do not discolour or stain, and maintain a sharp edge for a reasonable time.
Most “high-carbon” stainless blades are made of higher-quality alloys than less-expensive stainless knives, often including amounts of molybdenum, vanadium, cobalt, and other components intended to increase strength, edge-holding, and cutting ability. Almost all of our Stainless steels blades are made of High Carbon Stainless steels.

SG-2 (Super Gold No.2)
This is more common and popular powdered High Speed Tool Steel for knife blades. You can taste speechless cutting performance, great edge retention and easy maintenance (resistance for the rust). Made by Takefu steel company. Achieves very high hardness. Some high-class knives are made of this SG-2, Elite line of Shun and Yaxell GOU series.

VG-10
One of most popular and high ranked Japanese Stainless Steel for sharpness, edge retention and durability. Cobalt added Special high Carbon Stainless Steel, often be called as “Cobalt Steel”. Many of makers use VG-10 for the Damascus blade too.

VG-1
This is good basic and common Japanese Stainless steel which makes high hardness, edge retention, strength and rust resistance. Both VG-1 and VG-10 are produced from Takefu Steel Company.

Gingami No.3(Gin-san)
Fine Japanese Steel Company Hitachi’s special stainless steel which makes similar sharpness, edge retention as Carbon Steel. Gingami No.3 often be used for Japanese Traditional Style knives.

Sweden Stainless Steel
The Pure Stainless Steel material from Sweden. We heard several makers use Sweden Stainless Steels for the stable quality control. Selected Sweden Stainless steel material are easier for making process, heat-treating process, and it will help for making stable good quality control.

Molybdenum Vanadium Stainless Steel
One of common and good standard, stainless steel for the knife blades. We often recommend Molybdenum Steel Kitchen knives for hobby cooks and first-time buyers of Japanese knives because of its characteristics: ease of re-sharpening, good durability and rust resistance, and reasonable price range.

Elements of Steel

To put it simple: steel is iron with carbon in it. Other alloys are added to make the steel perform differently. Here are the important steel alloys in alphabetical order, and some sample steels that contain those alloys:

Carbon (C)
Increases edge retention and raises tensile strength. Increases hardness. Present in all steels, it is the most important hardening element. Also increases the strength of the steel but, added in isolation, decreases toughness. We usually want knife-grade steel to have >.5% carbon, which makes it “high-carbon” steel.

Cobalt (Co)
Increases strength and hardness, and permits quenching in higher temperatures. Intensifies the individual effects of other elements in more complex steels.  

Chromium (Cr)
Increases hardness, tensile strength and toughness. Provides resistance to wear and corrosion. Added for wear resistance, hardenability, and (most importantly) for corrosion resistance. A steel with at least 13% chromium is typically deemed “stainless” steel, though another definition says the steel must have at least 11.5% free chromium (as opposed to being tied up in carbides) to be considered “stainless”. Despite the name, all steel can rust if not maintained properly.

Molybdenum (Mo)
Increases strength, hardness, harden ability, and toughness.Improves machinability and resistance to corrosion. A carbide former, prevents brittleness & maintains the steel’s strength at high temperatures. Present in many steels, and air-hardening steels (e.g., A2, ATS-34) always have 1% or more molybdenum — molybdenum is what gives those steels the ability to harden in air.

Nickel (Ni)
Adds toughness. Present in L-6 and AUS-6 and AUS-8. Nickel is widely believed to play a role in corrosion resistance as well, but this is probably incorrect.

Tungsten (W)
Adds strength, toughness, and improves hardneability. A carbide former, it increases wear resistance. When combined properly with chromium or molybdenum, tungsten will make the steel to be a high-speed steel. The high-speed steel M2 has a high amount of tungsten. The strongest carbide former behind vanadium.

Vanadium (V)
Increases strength, wear resistance, and increases toughness. Contributes to wear resistance and hardness, and as a carbide former (in fact, vanadium carbides are the hardest carbides) it contribute to wear resistance. It also refines the grain of the steel, which contributes to toughness and allows the blade to take a very sharp edge.

For more complex chart on steel composition elements, check our other article. Enjoy and happy knife hunting!

Originally Yasugi or Yasuki steel was made from the steel produced from sand iron at a plant in Yasugi city in Shimane perfecture. Tartara steel is also made there. The plant is now owned by Hitachi which produces a wide range of steels.
Yasuki steel can be yellow, white or blue. Because it is Japanese made, it is considered nihontetsu 日本鉄. You can bet the grades of Yasuki steel used by better makers. Yasugi white and blue are really high class and some used by Tasai which is listed as near to Aogami Blue Steel quality. The only exception is Yasugi yellow – this is a cheap steel of lower quality, hence great Japanese blacksmiths do not use it in production (you may find some in Pakistani or Chinese counterfeit versions of Japanese knives).

yasugi city steel produced
Yasugi is a native steel produced in Japan which makes a patriotic Japanese chefs more than happy to buy knives with Yasugi steel. We are lucky to offer few Yasugi steel knives of great Yoshihiro blacksmith.

This is Yoshihiro Yamawaki Kurouchi Nakiri 165mm Yasugi Steel (blue)one of our bestsellers.

Yoshihiro Yamawaki Kurouchi Nakiri 165mm Yasugi Steel

 

 

In this article we will explain the differences between Shirogami (also called #1 steel) and Aogami (also called #2 steel).

  • The words Ao and Shiro mean blue and white.
  • Gami means metal.
  • The numbers 1 and 2 are grade differences. It all has to do with the carbon content and the alloy content.

Shirogami Steel

The white paper steel is super pure. It has very low alloy content and high carbon. It is super for hamon blades.

Aogami Steel

The blue paper has some alloying added, and is high carbon. It makes really sharp and tough working knives for chefs. These two steels are considered the cream of the crop in fine blades.

#2 steels often have karouchi finish, like this Yu Kurosaki Blue Super Cladd Kurouchi Japanese Chef’s Knife Gyuto 240mm:
yu kurosaki japanese knife

Suminagashi is a laminated billet with a white paper core and layered sides. It is a low-layer damascus with a medium thick solid core. The wavy upper sides add a good look to medium and large blades.
The laminated steel has a thin white paper core and soft iron ( like wrought iron) sides. It makes great slicers with a dark spine and a bright edge. When grinding it, you have to make sure you orient the core at the final edge. This makes a really good looking and tough small to medium size knife. It is also perfect for a tanto blade or small wakizashi.

Note: The main advantage of the low alloy is using a water or brine quench without warp and cracking.

Now, as far as equivalent in function and performance, many steels will be similar, but they won’t have the name recognition that Hitachi steel will give the knife.

Do you need help with choosing your perfect knife? Email us or just drop us a line on the livechat – are are pretty quick with responding 🙂