Knife Steel Information
There are many different types of knife steels available, each with its own set of unique metallurgy, traits and characteristics.
The two main umbrella terms used to describe the different kinds of steel are Stainless Steel and Carbon Steel.
Stainless steel is used to describe steel that has at least 10.5% chromium content by mass. It gains its 'stainless' properties primarily due to the presence of chromium (Cr), which is a key alloying element. This chromium content forms a passive oxide layer on the surface of the steel, which prevents corrosion and makes it "stainless", or resistant to rust and staining.
Japanese handmade kitchen knives often use specific stainless steels known for their performance, edge retention, and ease of maintenance.
Here are some of the main types of stainless steel commonly used for making Japanese cutlery and kitchen knives:
VG-10
Composition:
- Carbon: Approximately 1.00%
- Chromium: Approximately 15%
- Molybdenum: Approximately 1.00%
- Vanadium: Approximately 0.20%
Characteristics: VG-10 is known for its excellent edge retention, corrosion resistance, and ease of sharpening. It is popular among both professional chefs and enthusiasts for its overall performance and durability.
R2/SG2
Composition: R2 (also known as SG2) is a powdered metallurgy stainless steel with a composition that generally includes:
- Carbon: Approximately 1.25%
- Chromium: Approximately 14%
- Molybdenum: Approximately 2.30%
- Vanadium: Approximately 0.30%
Characteristics: R2/SG2 offers exceptional hardness, edge retention, and toughness. It is often preferred for its ability to maintain a sharp edge over extended use, making it suitable for high-end kitchen knives.
Ginsan (Ginsanko/Silver 3)
Ginsan, also known as Ginsanko or Silver 3, is a stainless steel alloy used primarily in the production of high-quality Japanese kitchen knives.
Maker: Ginsan steel is manufactured by Hitachi Metals Ltd.
Composition:
- Carbon (C): Approximately 0.95%
- Chromium (Cr): Approximately 13-15%
- Nickel (Ni): Approximately 0.60-1.00%
- Manganese (Mn), Silicon (Si), and other trace elements in smaller quantities.
Characteristics:
Ginsan steel offers good corrosion resistance due to its high chromium content, making it suitable for kitchen knives that are consistently exposed to moisture and acidic foods.
It provides good edge retention, allowing knives made from Ginsan steel to maintain sharpness through regular use.
Ginsan steel is relatively easy to sharpen compared to some other stainless steels. It responds well to traditional sharpening methods such as whetstones.
HAP40
Composition: HAP40 is a high-speed tool steel that is sometimes used in Japanese kitchen knives, with a composition that typically includes:
- Carbon: Approximately 1.30%
- Chromium: Approximately 4.00%
- Molybdenum: Approximately 5.00%
- Vanadium: Approximately 5.00%
Characteristics: HAP40 offers exceptional hardness, wear resistance, and edge retention. It is favored for its ability to maintain sharpness even under heavy use, making it suitable for professional kitchen environments.
ZA-18
ZA-18 is a stainless steel produced by Osaka Clad Co. It's known for its specific composition and properties suited for various industrial and knife-making applications. Here are the specifications and characteristics of ZA-18 stainless steel
Composition
-Carbon (C): Approximately 0.95-1.2%
-Chromium (Cr): Approximately 17-19%
-Nickel (Ni): Approximately 8-10%
-Molybdenum (Mo): Approximately 1.5%
-Copper (Cu): Approximately 1.00% (sometimes included for added corrosion resistance) -Cobalt (Co) Approximately 1.8%
-Other trace elements: Silicon (Si), manganese (Mn), sulfur (S), phosphorus (P)
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Characteristics:
- Corrosion Resistance: ZA-18 stainless steel offers excellent corrosion resistance due to its high chromium content. It is well-suited for applications where resistance to rust and oxidation is crucial.
- Strength and Toughness: With a balanced alloy composition, ZA-18 exhibits good mechanical properties, including strength and toughness, making it suitable for various industrial and knife-making applications.
- Machinability: ZA-18 is known for its good machinability, allowing it to be shaped and processed effectively in manufacturing processes.
- Heat Resistance: The addition of chromium and nickel provides ZA-18 with good heat resistance, making it suitable for applications requiring stability at elevated temperatures.
These stainless steels are chosen for their specific properties that cater to different preferences and needs among chefs and knife enthusiasts. They offer a range of performance characteristics from ease of maintenance and sharpening to superior edge retention and resilience in various kitchen tasks. Each steel type may be preferred by knife makers depending on their style, craftsmanship, and the desired qualities of the final knife product.
Here are some of the main types of Carbon steel commonly used for making Japanese cutlery and kitchen knives:
Shirogami
Also known as White Steel, or white paper steel is a type of high-carbon steel used primarily in the production of traditional Japanese kitchen knives.
Composition:
Shirogami #1 (White Steel #1):
- Carbon (C): Approximately 1.25-1.35%
- Manganese (Mn): Approximately 0.10-0.30%
- Silicon (Si): Approximately 0.10-0.30%
- Phosphorus (P) and Sulfur (S): Minimal amounts
- Iron (Fe): Balance
Shirogami #2 (White Steel #2):
- Carbon (C): Approximately 1.00-1.10%
- Manganese (Mn): Approximately 0.10-0.30%
- Silicon (Si): Approximately 0.10-0.30%
- Phosphorus (P) and Sulfur (S): Minimal amounts
- Iron (Fe): Balance
Hardness:
Shirogami steel is typically hardened to a high level, ranging from 60 to 65 HRC (Rockwell Hardness Scale). This high hardness allows it to take and maintain a very sharp edge.
Sharpness:
Shirogami steel is renowned for its ability to achieve and maintain an exceptionally sharp edge. This sharpness is favoured by chefs and knife enthusiasts for precise cutting tasks in the kitchen.
Edge Retention:
Shirogami steel holds its edge well, especially when properly sharpened and maintained. It is not as resistant to wear as some stainless steels but offers superior cutting performance due to its high carbon content.
Corrosion Resistance:
- Shirogami steel is a carbon steel and is not stainless, meaning it is susceptible to rust and corrosion if not properly cared for. Regular maintenance, including drying the blade after use and occasional oiling, is necessary to prevent corrosion.
Overall, Shirogami steel is highly valued for its purity, sharpness, and cutting performance, making it a preferred choice among chefs and knife enthusiasts who appreciate traditional Japanese craftsmanship and the superior edge quality offered by high-carbon steels.
Aogami
Also known as Blue Steel, or Blue Paper Steel, is a group of high-carbon steels commonly used in the production of Japanese kitchen knives.
Composition:
Aogami #1 (Blue Steel #1)
- Carbon (C): Approximately 1.10-1.30%
- Silicon (Si): Approximately 0.10-0.50%
- Manganese (Mn): Approximately 0.10-0.50%
- Phosphorus (P) and Sulfur (S): Minimal amounts
- Tungsten (W): Approximately 1.50-2.00%
- Chromium (Cr): Approximately 0.20-0.50%
- Vanadium (V): Approximately 0.10-0.30%
Aogami #2 (Blue Steel #2)
- Carbon (C): Approximately 0.95-1.05%
- Silicon (Si): Approximately 0.10-0.50%
- Manganese (Mn): Approximately 0.10-0.50%
- Phosphorus (P) and Sulfur (S): Minimal amounts
- Tungsten (W): Approximately 1.00-1.50%
- Chromium (Cr): Approximately 0.20-0.50%
- Vanadium (V): Approximately 0.10-0.30%
Hardness:
Aogami steel is typically hardened to a high level, ranging from 62 to 64 HRC (Rockwell Hardness Scale) after heat treatment. This high hardness contributes to its excellent edge retention.
Sharpness:
- Aogami steel is known for its ability to take and maintain a very sharp edge. The high carbon content, along with other alloying elements like tungsten and vanadium, allows it to achieve a fine, razor-sharp edge.
Edge Retention:
Aogami steel holds its edge exceptionally well, making it suitable for professional kitchen knives that endure heavy use. With proper maintenance and occasional sharpening, knives made from Aogami steel can maintain their sharpness over extended periods.
Corrosion Resistance:
Aogami steel is a carbon steel and is not stainless. It can rust and corrode if not properly cared for. Regular maintenance, including drying the blade after use and periodic oiling, is necessary to prevent oxidation.
Maker:
- Aogami steel is produced by several Japanese steel manufacturers, with Hitachi Metals Ltd. being one of the primary producers. They are known for their quality control and consistency in producing steels suitable for knife-making.
Overall, Aogami steel's combination of high carbon content and alloying elements makes it a preferred choice among knife makers and chefs seeking exceptional cutting performance and durability in their knives.
Aogami Super
Also known as Aogami Super Blue or AS steel, it is a premium high-carbon steel highly regarded in the world of Japanese kitchen knives.
Composition:
- Carbon (C): Approximately 1.40-1.50%
- Silicon (Si): Approximately 0.10-0.50%
- Manganese (Mn): Approximately 0.10-0.50%
- Phosphorus (P) and Sulfur (S): Minimal amounts
- Tungsten (W): Approximately 2.00-2.50%
- Chromium (Cr): Approximately 0.30-0.50%
- Vanadium (V): Approximately 0.10-0.30%
- Molybdenum (Mo): Approximately 0.30-0.50%
Hardness:
Aogami Super steel is typically hardened to a very high level, often reaching around 64-65 HRC (Rockwell Hardness Scale) after heat treatment. This high hardness contributes to exceptional edge retention.
Sharpness:
Aogami Super steel is renowned for its ability to achieve and maintain an incredibly sharp edge. The high carbon content, combined with alloying elements like tungsten and vanadium, allows it to attain a fine, razor-sharp edge that is highly prized by chefs and knife enthusiasts.
Edge Retention:
Aogami Super steel holds its edge exceptionally well, even under demanding use. Knives made from Aogami Super can maintain sharpness through prolonged cutting tasks and are favoured for their longevity between sharpening.
Corrosion Resistance:
Like other high-carbon steels, Aogami Super is not stainless and can rust if not properly maintained. Regular care, including drying the blade after use and periodic oiling, is necessary to prevent oxidation.
Applications:
Aogami Super steel is primarily used in the production of premium Japanese kitchen knives, particularly those crafted by skilled artisans using traditional forging techniques. It is valued for its superior cutting performance, edge retention, and the ability to achieve precise cuts.
Maker:
Aogami Super steel is produced by several Japanese steel manufacturers, with Hitachi Metals Ltd. being a prominent producer. They maintain stringent quality standards to ensure consistency and excellence in their steels used for knife-making.
Aogami Super steel represents the pinnacle of high-carbon steel craftsmanship in Japanese knife-making, offering exceptional sharpness, edge retention, and durability. It is a favourite among professional chefs and knife enthusiasts who appreciate knives that deliver outstanding cutting performance and can withstand rigorous kitchen use.
Where are these steels produced?
There are several Japanese companies renowned for their expertise in producing high-quality knife steels, each with its own specialty and reputation for excellence. Here are some prominent Japanese knife steel making companies:
Hitachi Metals Ltd.
Hitachi Metals is one of the most well-known manufacturers of specialty steels in Japan, including carbon steels (Shirogami, Aogami) and stainless steels (VG-10, Ginsan). They supply a wide range of steel grades used by knife makers and manufacturers worldwide.
Aichi Steel Corporation
Aichi Steel is another major Japanese steel manufacturer known for producing specialty steels used in various industries, including automotive and aerospace. They produce stainless steels like ZA-18 and possibly other alloys used in knife-making.
Takefu Special Steel Co., Ltd.
Takefu Special Steel specializes in producing high-performance tool steels and stainless steels that are highly favored by Japanese knife makers. They offer a variety of steel grades suitable for traditional and modern knife-making techniques.
Yasugi Specialty Steel
Yasugi Specialty Steel is part of Hitachi Metals Ltd. and is located in Yasugi City, Shimane Prefecture, Japan. They are known for producing traditional Japanese carbon steels used in knives, such as Shirogami and Aogami series.
Kawatoyo Cutlery
Kawatoyo Cutlery is a smaller-scale producer known for traditional Japanese knife-making. They offer a range of steels, including carbon and stainless varieties, crafted into knives renowned for their craftsmanship and performance.
Niigata Seiki Co., Ltd.
Niigata Seiki specializes in manufacturing high-quality stainless steels used in the production of kitchen knives and other cutlery items. They focus on providing steels with excellent edge retention and corrosion resistance.
Toyama Hamono Manufacturing Cooperative
The Toyama Hamono Manufacturing Cooperative is a collective of knife makers in Toyama Prefecture, Japan. They produce knives using locally sourced steels, often utilizing traditional forging methods and craftsmanship.
These companies play a crucial role in the Japanese knife-making industry, supplying knife makers and manufacturers with the high-quality steels needed to create knives renowned for their sharpness, edge retention, and durability. Their expertise in steel production ensures that Japanese knives continue to be highly regarded worldwide for their craftsmanship and cutting performance.
While there are other international companies and knife retailers who claim to use Japanese steel, Shinobi Industries takes pride in the fact that all of our knives are made in Japan by Japanese craftsmen using only the highest quality Japanese steel.