Japanese Knives Steel types: Unveiling The Soul of the Blade.

Japanese knives are often celebrated as the finest in the world, renowned for their incredible sharpness and ease of use. At the core of these exceptional tools lies the essence of their excellence: the steel.

Japan offers a remarkable variety of steel types used in the creation of knives, each contributing unique characteristics to their blade.

In this article, we will delve into the fascinating world of Japanese knife steel exploring the distinct properties of each type and providing you with a clear and comprehensive guide.
Whether you’re a seasoned chef or a home cook, this guide will help you navigate the blend of tradition and technology that defines Japanese knife-making.

 

CARBON STEEL CATEGORY

What is carbon steel?

Steel, Hagane (鋼) in Japanese, is primarily a blend of iron and a small proportion of carbon, typically ranging from 0.04% to 2%.
In knife production, two principal types of steel are utilized:
carbon steel (Tansan-kō 鉄炭鋼), which consists solely of iron and added carbon, and stainless steel (ステンレス鋼), which incorporates chromium in a mass percentage of at least 10.5%.

Carbon steel is particularly favored for crafting Japanese knife blades due to its ability to achieve an exceptionally sharp edge. This type of steel is created by introducing carbon into iron ore (Tekkō 鉄鉱), resulting in a carbon content ranging from 0.04% to 2.14%.
Carbon steel strikes an optimal balance, being both hard and capable of retaining a keen edge, making it a preferred choice for numerous Japanese kitchen knives.

TAMAHAGANE

Japanese name: 玉鋼

Tamahagane is a unique steel crafted from iron sand. It's rare and primarily used to forge Japanese swords, though a few high-cost items like kitchen knives are also made from it.

Tamagahane is produced using the traditional Tatara method (踏鞴製鉄 Tatara Seitetsu), which creates steel that has minimal impurities and a low carbon content ranging from 0.3% to 1.5%.

The term "Tatara" refers to the bellows used to supply air to the furnace.

SHIROGAMI

Japanese name: 白紙 , 白鋼
Alternative names: Shirokō, White Steel, White Paper Steel

Shirogami is a type of steel made by the Japanese company Hitachi Metals* It is famous for being very hard and for its ability to produce very sharp blades. However, compared to other steel alloys like Aogami, it tends to chip more easily.
The name Shirogami literally means “white paper” (白紙) because, after it’s made, it’s wrapped in white paper at the factory for easy identification.
It is also called Shirokō (白鋼), literally white steel.

Shirogami is quite expensive and is often used for traditional Japanese knives like Honyaki (本焼き). There are three types of Shirogami steel available: Shirogami #1, Shirogami #2, and Shirogami #3.

 

• SHIROGAMI #1
  Japanese name: 白紙１号 , 白一鋼
  Alternative names: Shiroichikō, White Steel #1, White Paper Steel #1
  
  This pure carbon steel is very popular for high-end Japanese knives, especially Honyaki (本焼き・ honyaki) blades.

  It's a really hard steel, but also quite brittle, so knives made from it need extra care when being used.
  Shirogami No.1 blades can be honed to a super fine edge, though they don’t retain their sharpness as well as other steels. They’re quite prone to rust, so make sure to wipe and dry them after every use to avoid corrosion.

  Shirogami #1 is almost the same as Aogami #1 steel but without Chromium and Tungsten. It is made up of Carbon 1.25 – 1.35%, Manganese 20 - 30%, Phosphorus  025%, Sulfur  004%, and Silicon 10 - 20%.

  Hardness (Rockwell Hardness Scale): 65 HRC and above
  Edge Retention: ●●●●
  
  
  
• SHIROGAMI #2
  Japanese name: 白紙２号 , 白二鋼
  Alternative names: Shironikō, White Steel #2, White Paper Steel #2
  
  Shirogami #2, or White Steel #2, is a popular high-carbon steel for Japanese kitchen knives, valued for its durability and ease of maintenance.
  Unlike Shirogami #1, it is less prone to chipping, and its purity and fine grain allow for exceptional sharpness and cutting precision.
  
  Even though it is a simple carbon steel, it holds its edge well and is easy to re-sharpen making it an ideal choice for beginners in the world of Japanese knives.
  
  Hardness (Rockwell Hardness Scale): 60 – 63 HRC
  Edge Retention: ●●●●●
  
  
  
• SHIROGAMI #3
  Japanese name: 白紙３号 , 白三鋼
  Alternative names: Shirosankō, White Steel #3, White Paper Steel #3
  
  Shirogami #3 steel is exceptionally durable and less prone to chipping compared to Shirogami #1 and #.2. However, it requires more effort to sharpen.
  Among the three grades of white steel, Shirogami #3 has the least carbon content, making it the toughest and most chip-resistant. On the downside, this also means it has the shortest edge retention.
  
  Hardness (Rockwell Hardness Scale): 60 HRC
  Edge Retention: ●●

 

AOGAMI

Japanese name: 青紙 , 青鋼
Alternative names: Aokō, Blue Steel, Blue Paper Steel

Aogami steel is a type of steel produced by the Japanese company Hitachi Metals* It is a high-carbon steel, a quality that makes the blades forged from it capable of achieving excellent sharpness. Additionally, its ability to maintain a sharp edge makes it particularly suitable for the creation of kitchen knives.
Its name literally means “Blue Paper,” (青紙) due to the color of the paper in which it is wrapped at the factory after production for easy identification. 
It is also called Aokō (白鋼), literally Blue Steel.

Aogami steel is available in the following variants: Aogami #1, Aogami #2, and Aogami Super.

• AOGAMI SUPER
  Japanese name: 青紙スーパー, 青紙スーパー鋼
  Alternative names: Aogami Supa Hagane, Blue paper super, Blue steel super
  
  Aogami Super (青紙スーパー ・Aogami Sūpā) stands out as one of the premier types of carbon steel used in knife making, particularly prized for its exceptional sharpness.
  With a hardness rating of 65-68 HRC, it surpasses other carbon steels, meaning knives made from it require less frequent sharpening.
  
  Aogami Super contains 1.40%-1.50% carbon, similar levels of chromium and tungsten as Aogami No.1, along with additions of molybdenum (0.30-0.50%) and vanadium (0.5%).
  
  Hardness (Rockwell Hardness Scale): 65 – 68 HRC
  Edge Retention: ●●●●●
  
  

  Check our Aogami Super Steel - Santoku Japanese Knife | Anryu Cutlery | 165mm (6.5")

  
  
  
• AOGAMI #1
  Japanese name: 青紙１号, 青一鋼
  Alternative names: Aoichikō, Blue Paper Steel #1, Blue Steel #1
  
  Aogami #1 steel is renowned for its high carbon content and elevated levels of chromium and tungsten compared to Aogami #2. As a result, it can be sharpened to an exceptionally fine edge but is less resilient than Aogami #2 and also carries a higher price tag.
  Nevertheless, its superior grip and resistance to wear make it a preferred option for those seeking top-tier cutlery.
  Aogami #1 contains 1.25 - 1.35% carbon, 0.20 - 0.50% chromium, 0.20 - 0.30% manganese, 0.03% phosphorus, 0.004% sulphur, and silicon at 0.10 - 0.20%.
  
  Hardness (Rockwell Hardness Scale): 63 – 65 HRC
  Edge Retention: ●●●●
  
  

• AOGAMI #2
  Japanese name: 青紙２号, 青二鋼
  Alternative names: Aonikō, Blue Paper Steel #2, Blue Steel #2
  
  Aogami #2 is the most commonly used type of Aogami steel, prized for its easy sharpening and resistance to chipping, making it the benchmark for Aogami steel knives. It holds a more robust edge compared to Aogami #1, though it sacrifices a bit of sharpness.
  
  Created by adding chromium and tungsten to Shirogami #2, this steel becomes tougher and more resistant to wear and tear.
  It's the perfect choice for beginners venturing into Aogami steel knives, and its widespread popularity among users speaks to its quality and performance.
  
  Aogami #2 consists of 1.05 - 1.15% carbon, 0.20 - 0.50% chromium, 0.20 - 0.30% manganese, with traces of phosphorus and sulfur, plus 0.10 - 0.20% silicon and 1.00 - 1.58% tungsten.
  
  Hardness (Rockwell Hardness Scale): 62 – 65 HRC
  Edge Retention: ●●●●●

 

KIGAMI

Japanese name: 黄紙（黄鋼）
Alternative names: Kihagane, Yellow Paper Steel, Yellow Steel

Yellow Steel (黄紙・Kigami) from Hitachi Metals* is a grade of steel that ranks higher than the SK series but falls below Aogami or Shirogami in terms of quality.
Nowadays, Yellow Steel sees less use as Aogami and Shirogami have gained popularity.

It's typically chosen for high-end tools and mid-range kitchen knives, commonly found in demanding settings such as culinary schools and fish processing facilities.
Users appreciate its affordability and ease of sharpening.

 

• KIGAMI #2
  Japanese name: 黄紙２号
  Alternative names: Yellow Paper Steel #2, Yellow Steel #2
  
  Kigami #2 is among the more economical steel to manufacture in Japan, resulting in knives made with this material being budget-friendly.
  These blades are easy to sharpen and less costly compared to other steels, although they are prone to chipping.
  
  This type of steel is commonly found in places such as schools and factories, where knives require regular sharpening.
  
  Hardness (Rockwell Hardness Scale): 60 – 61 HRC
  Edge Retention: ●●

 

• KIGAMI #3
  Japanese name: 黄紙3号
  Alternative names: Yellow Paper Steel #3, Yellow Steel #3
  
  Kigami #3  has a lower carbon content than Kigami #2, making it slightly different in terms of hardness and performance.
  
  Hardness (Rockwell Hardness Scale): 60 – 61 HRC
  Edge Retention: ●●

SK

Japanese name:  SK材
Alternative names: SK Steel
SK Series Including: SK#3 (SK105), SK#4 (SK95), SK#5 (SK85)

In Japan, SK steel is called “S-K zai” (SK材). The “S” stands for Steel, the “K” stands for Kougu (工具 [tool]), and “Zai” (材 [material]). So, “S-K zai” translates to “Steel Tool Material.” As the name suggests, SK steel is widely used in various products, including tools and not just knives. 

It's crucial to note that SK steel is a broad classification established by the Japanese Industrial Standards (日本工業規格, Nihon Kōgyō Kikaku), with numerous manufacturers producing it. Often, knife makers rebrand SK steel under their own labels or simply market it as "high carbon steel." If you encounter an affordable Japanese knife made from high-carbon steel without a specified type, it likely utilizes SK steel.

The classification of SK materials, previously ranging from SK1 to SK7 based on carbon content, has expanded to 11 types. Notably, SK85 now corresponds to the former SK5 (0.85% carbon), SK95 to SK4 (0.95% carbon), and SK105 to SK3 (1.05% carbon).

Check our SK Carbon Gyuto Japanese Knife | Minamoto Mitsukane | 210mm (8.3")

HAP 40

Japanese name:  HAP 40
Alternative names: -

HAP-40 steel, crafted by Hitachi Metals*, stands out in the world of Japanese cutlery for its exceptional strength and durability, thanks to a process called powder metallurgy. Some knife aficionados regard it as possibly the finest Japanese cutlery steel available today. It falls into the category of "semi-stainless" steel (半ステンレス鋼, han-sutenresu-kō), meaning it lacks sufficient chromium for full stainless status but offers better rust resistance compared to standard carbon steel, with chromium levels ranging from 3.70% to 4.70%.

In addition to carbon (1.27% to 1.37%) and chromium, it boasts significant amounts of tungsten (5.60% to 6.40%), molybdenum (4.60% to 5.40%), vanadium (2.80% to 3.30%), and cobalt (7.50% to 8.50%). These elements contribute to its remarkable hardness, making it one of the toughest steels on the market. HAP-40 can achieve extremely high levels of hardness, ensuring prolonged sharpness and exceptional cutting performance. It stands up well against other premium steels like Aogami Super but offers greater resilience, reducing the risk of chipping.

The primary drawback of HAP-40 is its higher cost. However, for knife enthusiasts seeking top-tier materials and willing to invest a bit more, a knife crafted from HAP-40 steel is definitely worth considering.

Hardness (Rockwell Hardness Scale): 64 – 68 HRC
Edge Retention: ●●●●●

STAINLESS STEEL CATEGORY

What is Stainless steel?

Stainless steel, known as “Sutenresu Hagane” (ステンレス鋼) in Japanese, is a steel alloy that includes chromium. To be classified as stainless, the alloy needs to contain at least 10.5% chromium by weight. Chromium provides the steel with excellent resistance against rust and corrosion. This alloy can also incorporate other elements such as nickel, molybdenum, and vanadium to improve its characteristics.

 

VG-1

Japanese name: V金1号
Alternative names: V Gold 1

VG1 is a high-quality steel used for making knives.
The name comes from “V金1号 (V-kin-1-gō),” where “金 (kin)” means gold, indicating its high quality.
It was developed by the Japanese Takefu Special Steel Company before VG10 and is known for its excellent ability to keep a sharp edge.

It typically has a hardness rating between 58 and 61or higher on the Rockwell scale and contains 0.95–1.05% carbon, 13–15% chromium, and 0.2–0.4% molybdenum.

Hardness (Rockwell Hardness Scale): 58– 61 HRC
Edge Retention: ●●●●

Check our VG-1 Santoku Japanese Knife ｜Masutani Cutlery | 140mm (5.5") - Red

VG-10

Japanese name: V金10号
Alternative names: V Gold 10

VG-10 is a popular Japanese stainless steel for knives. The name comes from “V金10号 (V-kin-10-gō),” where “金 (kin)” means gold, indicating its high quality.
Produced by Takefu Special Steel Company, VG-10 is an improvement over VG-1. They also make VG-10W, which includes tungsten for added durability.
Japanese kitchen knives made from VG-10 perform well and require less maintenance.

Also known as V Gold 10, this steel is hard and tough, with excellent edge retention and a hardness rating of 60-61 HRC.

It contains 1% carbon, 15% chromium, 1% molybdenum, 0.2５% vanadium , and 1.5５% cobalt.

Hardness (Rockwell Hardness Scale): 60– 61 HRC
Edge Retention: ●●●●

Check our  VG-10 Petty Japanese Knife ｜Tanaka Shigeki｜150mm (5.9")

AUS8

Japanese name:  AUS8 鋼
Alternative names: AUS-8 Steel

AUS8 steel, produced by Aichi Steel, is an excellent pick for newcomers to Japanese knives. This stainless steel is famed for its rust resistance, durability, toughness, and solid wear resistance. AUS8 blades are easy to sharpen and wallet-friendly, making them a fantastic choice for first-time users of Japanese knives.

Hardness (Rockwell Hardness Scale): 58– 60 HRC
Edge Retention: ●●●

AUS10

Japanese name: AUS10 鋼
Alternative names: AUS-10 Steel

AUS-10 steel, also from Aichi Steel, shares similarities with AUS8 but offers improved edge retention and sharpness, positioning it as a higher-tier option over AUS8.

Despite being categorized as entry-level among Japanese knife steels, AUS-10 delivers superior cutting performance and edge retention due to its increased carbon content. AUS-10 boasts robust qualities including wear resistance, toughness, and ease of sharpening.

Knives crafted with AUS-10 are budget-friendly and user-friendly, making them an ideal choice for newcomers to Japanese knife craftsmanship.

Hardness (Rockwell Hardness Scale): 58– 60 HRC
Edge Retention: ●●●●


Check our AUS-10 Nakiri Japanese Knife | Vegetable knife | 160mm (6.3")

SILVER #3

Japanese name:  銀三鋼
Alternative names: Ginsanko, Gingami #3, Gin-3

Silver #3, also known as Ginsan-kō among other names, is a popular steel produced by the Japanese company Hitachi Metal*.
It's highly esteemed among skilled knifemakers who specialize in creating premium Japanese knives in the mid to high-end range.
It blends the sharpness and hardness typical of high-carbon steel with the crucial benefit of stainless steel: resistance to rust.
Comparable to Shirogami high-carbon steel in cutting ability, Silver-3 surpasses it with superior rust resistance. Contrasted with the popular VG-10 stainless steel, Silver-3 sacrifices a bit of rust resistance but compensates with greater strength and ease of sharpening. Knives made from Silver-3 typically achieve a hardness between HRC 59-64.

Thanks to its exceptional cutting performance, Silver-3 is a preferred stainless steel for crafting traditional Japanese-style knives (和包丁, wabōchō), often featuring single-bevel blades. It's an excellent choice for those seeking intermediate to high-end stainless steel knives. If you prioritize quality and don't mind a little extra care, Silver-3 deserves serious consideration.

Hardness (Rockwell Hardness Scale): 59– 64 HRC
Edge Retention: ●●●

 

DP GOLD

Japanese name:  DPゴールド
Alternative names: -

DP-Steel (Dual Phase Steel): This steel undergoes a special process called DP (Dual Phase), which is crucial for its unique properties. The process involves heating the steel to a high temperature and then rapidly cooling it. This creates a microstructure with two different parts: ferrite and martensite. Ferrite is soft and adds flexibility, while martensite is hard and adds strength. This combination makes DP-Steel both strong and flexible, perfect for making durable and sharp kitchen knives. The name DP Gold comes from the use of V Gold steel in this special process.

Hardness (Rockwell Hardness Scale): 58– 61 HRC
Edge Retention: ●●●●

Check our DP-Gold Gyuto Japanese Knife｜Masutani Cutlery｜210mm (8.3")

 

MOLYBDENUM VANADIUM STEEL

Japanese name: モリブデン・バナジウム鋼
Alternative names: Mo-V Steel

Molybdenum Vanadium Steel (Mo-V Steel), refers to a category of knife steels incorporating both Molybdenum and Vanadium. For instance, AUS-8 and Aus10, while often marketed under their own brand names, fall into this group.

Some knife makers choose to label their products as "Molybdenum Vanadium steel" or simply "Molybdenum steel," possibly to avoid mentioning specific brand affiliations or due to using unique steel blends.

The inclusion of Molybdenum and Vanadium enhances the steel's hardness, strength, toughness, and wear resistance compared to steels lacking these elements. Molybdenum additionally contributes to improved corrosion resistance.

Hardness (Rockwell Hardness Scale): Varies with alloy
Edge Retention: Varies with alloy

POWDERED HSS

Japanese name: 粉末ハイス鋼
Alternative names: Powdered High-Speed Steel

Powdered High-Speed Steel (Powdered HSS) stands out as a modern marvel in stainless steel, renowned for its exceptional sharpness and hardness.
Originally developed for tough applications like drills, High-Speed Steel (HSS) was prized for maintaining its hardness even under high temperatures. However, its coarse metal structure limited its suitability for knives
The innovation of powder metallurgy has revolutionized this material, enabling the production of fine particles that are ideal for crafting knives. This advanced technique not only preserves sharpness but also enhances ease of sharpening and resistance to chipping, while maintaining exceptional hardness.

Consequently, Powdered HSS has become the preferred choice for those seeking a blend of durability and precise cutting performance.

Hardness (Rockwell Hardness Scale): up to 70
Edge Retention: ●●●●

 

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In summary, the steel used in Japanese knives is the cornerstone of their renowned sharpness and durability. From the traditional high-carbon steels to the advanced stainless varieties, each type of steel offers unique benefits that cater to different needs and preferences.

Understanding these differences can help you make an informed choice, ensuring you get the best performance from your Japanese knife.

*Note on Hitachi Metals Ltd

Please note that as of January 2023, Hitachi Metals Ltd has been renamed Proterial Ltd.. However, we have retained the name Hitachi in this article, as many knife enthusiasts may be more familiar with this name.