Information About Blade Steel

Information About Cutlery Steels

High quality steel alone does not guarantee a high quality knife blade, as the microstructure of the steel can be significantly affected by the forging techniques, forging temperatures and heat treatment methods used during its manufacture. Each of the various cutlery steels also has different characteristics, so they might not be suitable for a particular blade geometry or cutting task. One secret behind the sharpness and cutting performance of Japanese knives lies in the traditional forging and heat treatment techniques used by the blade smiths, many of these techniques have been in use for several hundred years and were originally developed by Japanese sword smiths. Similarly, the geometry of the blades that they make are typically based upon traditional forms which have stood the test of time, in some cases for several hundred years. The knives we sell are made by experienced blade smiths and craftsmen who understand how to extract the best characteristics from the steels they work with and also which forging techniques, heat treatment procedures and blade geometries are suitable for each of the different types of knife that they produce. They pay extra attention during the forging, grinding and heat treatment processes because they know that poor technique or the use of inappropriate methods can cause irreversible damage to the blade steel or negatively affect edge sharpness, edge retention, blade toughness, or ease of sharpening. While all of our specially selected knife makers and craftsmen make every attempt to make produce knives that are excellent in every regard, we especially recommend knives made by Hattori, Misono, Mizuno Tanrenjo, Sukenari and Mr. Itou due to their consistently high standards of quality.

              As you can see from our selection of fine Japanese knives, there are many kinds of steels being used to make kitchen knives. On this webpage, we would like to discuss the different characteristics of each of the different steels that are commonly used to make Japanese kitchen knives. Below we have classified these steels in to three basic groups: 

• Carbon Steels (An alloy of Iron and Carbon, in which the main interstitial alloying constituent is Carbon)

• Stainless Steels (Steels with a minimum of 10.5% Chromium content by mass) 
• Powdered Metallurgy Steels / Powdered High Speed Tool Steels (Steels which are made from powdered metal)

We hope that reading the information below will help you to identify steels which meet your specific requirements. Our new website will allow you to quickly and easily find all of the knives that we offer in the particular steel that you are interested in. But first, let’s take a look at the various different elements that are added to steel alloys and how they are used to alter the characteristics of the alloy.

Elements That Are Added To Steel Alloys and Their Typical Effects

   Just like seasonings alter the taste of food, the characteristics of a steel alloy can be altered by the addition of different chemical elements and compounds. Used carefully, this technique allows the production of steel alloys which are tailor-made for a specific application but care must be taken because, depending upon the volume or mass of an element added to an alloy, negative as well as positive effects might be produced. In addition, the effects that an element produces can vary significantly depending on which other elements are also included in the steel alloy, and also the percentage of the alloy that these elements account for. The subject of metallurgy is a very complex science, so please consider the information presented here as a basic guide only.

• Carbon (C)

Increases edge retention, tensile strength and the hardness which is attainable.

• Chromium (Cr)

Increases hardness, tensile strength and toughness. Improves resistance to corrosion. Can  also improve wear resistance in complex steel alloys.

• Cobalt (Co) 

Increases strength and hardness. Permits quenching at higher temperatures. Intensifies the individual effects of other elements in more complex steels.

• Molybdenum (Mo)

Increases strength, hardness, hardenability, and toughness. Improves machinability and resistance to corrosion. 

• Tungsten / Wolfram (W)

Adds strength and toughness. Improves hardenability.

• Vanadium (Va)

Increases strength, wear resistance, and toughness. Limits grain size.
 

After significant research and technological development Japanese steel makers are now able to make special laminated steels called “Fukugozai” , which  are comprised of multiple layers of different types of steel alloy. This innovative industrial production method resulted in worldwide acclaim because it enabled the economical creation of knives which have the advantages of a high performance carbon steel core and the additional benefit of a corrosion resistant stainless steel cladding - Something that is extremely difficult to achieve using traditional blade smithing methods. In the future, Japan will continue to develop and offer new products using advanced steels and steel production methods.

Stainless Steels

   Stainless steel has typically been defined as any steel alloy which has a minimum of 10.5% Chromium content by mass. However, due to the development of Powdered Metallurgy Steels that contain a lot of Carbon (Which can form Chromium Carbides and thus reduce the corrosion resistance of the steel), one steel manufacturer has suggested a new definition in which a steel is only considered to be ‘stainless' if the Chromium content is twelve times higher than the Carbon content. One key benefit of Stainless Steels is their high corrosion resistance, which makes them easy to maintain when compared to Carbon Steel knives, which rust fairly easily if not properly cared for. Stainless Steel knives are particularly useful for our customers who often work with moist or wet foods, salty foods, or acidic foods such as fruit. A further benefit of Stainless Steel knives, as long as they do not contain a significant volume of other alloying elements, is that the Chromium forms bonds with some of the Carbon and produces Chromium Carbide, a very hard ceramic compound that increases the edge retention of knives. 

Cutting tools made from early Stainless Steels had a reputation for being relatively difficult to sharpen and also poor edge sharpness, but since the latter part of the 20th Century this has no longer been the case. Due to years of research and development the Stainless Steels that are available today offer excellent performance in terms of corrosion resistance, edge sharpness, edge retention and ease of sharpening. Sometimes you may hear or see some modern Stainless Steels being referred to as “High Carbon Stainless Steels”, this is because they have a relatively high carbon content and also compare favorably with ‘ regular' High Carbon Steels in terms of edge sharpness, edge retention, and ease of sharpening. All of the Stainless Steel knives that we carry are made from “High Carbon Stainless Steel” and they proved to be very popular with many of our customers who desire knives that are not only easy to care for, but and also have very good cutting performance.

An Important Note About Stainless Steel Knives

Whilst Stainless Steel knives have very good corrosion resistance, it is important to remember that they are not totally 'stain-proof’ or 'rust-proof'. They will discolor if you leave them in contact with water for a prolonged period of time and they can also rust, particularly if they are left in contact with salty ingredients or salty liquids. To keep your knife in good condition we recommend that you wipe it with a clean cloth after hand washing it with dish detergent. We also recommend that you wipe wooden handles dry after use because this will minimize the risk of cracking, which often occurs when wood has to rapidly release a lot of moisture to reach equilibrium with a much drier environment. This basic daily maintenance is important for all kitchen knives and they should last you a lifetime if they are properly cared for.

VG-10 / V Gold 10 
 VG-10 (Takefu Special Steel Co., Ltd.) is one of the most popular and highly regarded Japanese Stainless Steels for making cutlery. It has strong corrosion-resistance and can provide very good edge sharpness and edge retention. VG-10 belongs to a group of steels called "Cobalt Steels”, but it also contains Vanadium, which improves its strength, toughness and edge retention.

VG-1 / V Gold 1

VG-1 (Takefu Special Steel Co., Ltd.) is an affordable Japanese Stainless Steel that is popular for making cutlery. It has good corrosion resistance, edge retention and edge sharpness and is capable of achieving a relatively high Rockwell hardness.

Gingami No.3 ("Silver Paper No.3”) / Gin#3 ("Silver#3") / Ginsan-kō ("Silver 3 Steel")

Gingami No. 3 (Hitachi Metals Ltd.) is a very fine-grained Stainless Steel that can attain edge sharpness and edge retention comparable to some High Carbon Steels. It has even been used to create corrosion-resistant versions of Japanese traditional single bevel knives. It is very popular with both professionals and home cooks and is generally believed to be slightly easier to sharpen than VG-10.

Swedish Stainless Steel
 For hundreds of year’s Swedish steel has had an excellent reputation because of its consistently high quality and purity. Modern Swedish Stainless Steels maintain these high standards and are also corrosion-resistant. They are popular with Japanese blade smiths due to their predictable nature and fine microstructure after heat treatment, which allows excellent edge sharpness.

Molybdenum Vanadium Stainless Steel（AUS-8）
 AUS-8 (Aichi Steel Corp) is a competitively priced Molybdenum Stainless Steel that is very popular with high volume knife producers. We always recommend that less experienced knife users buy Molybdenum steel kitchen knives because of they are reasonably priced, easy to sharpen and have excellent corrosion-resistance. AUS-8 also incorporates Vanadium, which further improves the strength, toughness, and edge retention of the steel.

Carbon Steel
   Carbon steel is typically defined as an alloy of Iron and Carbon in which the main interstitial alloying constituent is Carbon (Ranging between 0.12–2.0%). Some definitions also state that their total mass should contain no more than 1.65% Manganese and no more than 0.60% Copper. Unlike Stainless Steel, Carbon Steel contains either little or no elements that reduce corrosion, which means that it can discolor and rust relatively easily. Consequently, it requires more care and maintenance than Stainless Steels. 

We recommend that you do not leave Carbon Steel knives in wet conditions or in contact with water for any significant length of time because it can cause discoloration and eventually lead to rusting. If you often work with wet foodstuff, please keep a soft absorbent cloth or towel nearby so that you can frequently dry the knife whilst working. We similarly recommend that Carbon Steel knives that come in to contact with salty foods or liquids should be cleaned as soon as possible in order to prevent corrosion. It is normal for an oxidized ‘patina’ to develop on knives which are used with acidic foods or foods which contain a lot of protein. Some people like this discoloration and it does not affect cutting performance, but it can easily be removed using cloth and some mildly abrasive cleaning powder, such as Bar Keepers Friend. This cleaning method will minimize the chance of damaging the appearance of the knife. To remove more serious corrosion and rust we suggest using the ‘rust eraser’ type of abrasive rubber blocks, starting with the finest abrasive version first, to minimize damaging the appearance of the knife. 

It is also especially important to dry the blade and handle of Carbon Steel knives after hand washing because any remaining water might lead to discoloration and eventual rusting. Before storing the knife, we advise that the blade is given a very light coat of a non-perishable oil that is relatively P.H. neutral, such as camellia oil (Tsubaki Oil), jojoba oil, Ballistol All-purpose Oil, or mineral oil. Place a small drop of the oil on a soft clean cloth, kitchen paper, or a disposable tissue. After oiling, please put the blade back inside the folded piece of corrosion-inhibiting paper that it was originally shipped with, as it will help to prevent corrosion.

Having read about the special care and maintenance that Carbon Steel kitchen knives require, you might wonder why some people prefer them to Stainless Steel knives. Some people continue to use Carbon Steel knives due to their respect for cultural traditions, whilst others believe that they offer a better balance of edge sharpness, edge retention and ease of sharpening than Stainless Steel knives. Indeed, because many culinary professionals need a knife that retains maximum sharpness throughout their long working day that is also easy to sharpen, they prefer to use High Carbon Steel knives. This is why they are very popular with professionals who make dishes that use raw ingredients, such as Sashimi (Raw fish) and salads, since the ingredients have to be cleanly cut in order to retain the best possible texture and flavor (Roughly cut surfaces frequently suffer from excessive oxidation, which can spoil the flavor of the food). Many knife enthusiasts also prefer Carbon Steel knives because, unlike Stainless Steel knives, they can build up a patina which they believe adds personality, history and beauty to a knife.

Just as the legendary cutting performance of Japanese swords made of Tamahagane (“Jewel Steel”) is known worldwide, Japanese Carbon Steel kitchen knives also offer excellent cutting performance. In fact, the high purity Shirogami ("White Steel”) group of steels, which are made at the Yasugi steel works of Hitachi Metals Ltd., were originally developed to emulate many of the desirable qualities of Tamahagane (“Jewel Steel”). Hitachi use White Steel No.2  as the starting point for creating many of the other steels which they produce, including White No.1 steel, the Aogami ("Blue Steel”) range of steels and also Aogami Super steel.

A Note About Laminated Carbon Steel Knives and the “CarboNext (ES) Series”

For customers who would like to try the benefits of a High Carbon Steel blade, but are worried about corrosion, we recommend trying a knife with a laminated blade that features a High Carbon Steel blade core and outer cladding layers of either soft Stainless Steel or beautiful 'Stainless Damascus Steel'. Because only the central core of these laminated knives has the possibility of discoloring or rusting, these knives are much easier to care for than regular Carbon Steel knives. Alternatively, please consider our innovative “CarboNext (ES) Series” of knives, which offer the same advantages as High Carbon Steel knives but also better corrosion resistance.

"White Steel No.2" (Shiroko No.2) / "White Paper No.2" (Shirogami No.2)

White Steel No.2 (Hitachi Metals Ltd.) has minimal impurities and a very fine grain structure, so it is ideal for fine cutting tools such as Japanese traditional-style knives. Despite being a ‘simple’ carbon steel,  White Steel No.2 has very good edge retention and it is also very easy to re-sharpen. Recommended for first-time users of Japanese traditional-style knives.

"White Steel No.1" (Shiroko No.1) /  "White Paper No.1" (Shirogami No.1) 

White Steel No.1 (Hitachi Metals Ltd.) is made by further refining White Steel No.2 and adding more Carbon. The extra Carbon allows it to achieve a slightly higher HRc. than White Steel No.2, but also makes it a bit more brittle. White No.1 is very popular with professional chefs who make traditional Japanese cuisine because it can be sharpened to an exceedingly fine edge, has very good edge retention and is easy to re-sharpen.

"Blue Steel No.2” (Aoko No.2) / “Blue Paper No.2" (Aogami No.2)

Blue Steel No.2 (Hitachi Metals Ltd.) is made by adding Chromium and Tungsten / Wolfram to White Steel No.2. This results in increased toughness and the production of hard carbide molecules which improve edge retention. Many knife users have noted that while Blue Steel No.2 is very similar to White Steel No.2 in terms of edge sharpness, it has slightly superior edge retention.

"Blue Steel No.1” (Aoko No.1) / “Blue Paper No.1" (Aogami No.1) 

Blue Steel No.1 is very similar to Blue Steel No.2, but the additional Carbon and Tungsten result in even better wear resistance / edge retention and toughness. The steel is perhaps most commonly seen in traditional Japanese single-bevel edged knives.

Aogami Super / Blue Super Steel

Aogami 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 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.

Powdered Metallurgy Steels / Powdered High Speed Tool Steel

   Powder Metallurgy Steels (P.M. steel) and Powdered High Speed Tool Steels are an interesting group of steels that are often used in industrial applications that require tools capable of cutting steel and also withstanding tremendous forces and high temperatures. P.M. steels are made using a variety of proprietary methods, but the basic process usually involves atomizing molten steel by spraying it through a very fine nozzle and in to a container of liquid nitrogen. This produces microscopic droplets of steel with a very fine grain structure and excellent metallurgical properties. Once the resulting powdered steel has been cleaned and sorted, according to the size of the droplets, it is sintered in to an ingot using a hot isostatic press. This process involves heating the metal to just below its melting point and applying extremely high pressure in order to consolidate the steel and remove voids.

For users of kitchen knives, the main benefits of P.M. steels are typically considered to be:

• The ability to make higher alloy grades of steel than traditional steelmaking methods.
• The ability to achieve a higher Rockwell C hardness without sacrificing toughness. This can enable a knife edge that is resistant to plastic deformation (e.g.'edge rolling') without being prone to chipping.
• Steel which is easier to grind and sharpen than similarly formulated steels made using conventional steel manufacturing methods.
• A highly consistent microstructure that allows knife manufacturers to more reliably predict tool performance and control for tool failure.
• Chromium alloy steels which are typically more resistant to corrosion than their conventionally made equivalents.

Accordingly, we especially recommend knives made with Powder Metallurgy Steels to serious knife enthusiasts and culinary professionals who demand knives with the best possible edge retention and cutting performance.

Cowry X
   Due to the expense and technical difficulty of manufacturing knives made with Daido Steel Company’s special Cowry X steel, we unfortunately do not often have the opportunity to offer these superb knives to our customers. Mr. Hattori is one of only a few highly experienced knife makers that have been able to master the art of forging and heat treating this technically demanding steel. This is truly a shame because, ideally, we would like all of our customers to be able to experience this fantastic premium knife steel.

ZDP-189
   Hitachi Metals Ltd. developed their special ZDP-189 steel as a competitor to Cowry X steel, which is made by Daido Steel Company. ZDP-189 has similar chemical composition to Cowry X and is generally considered to offer a similar level of performance. Unfortunately, due to a difficulty of making this steel and the special forging and heat treatment it requires, knives made in this steel are expensive and are consequently rarely seen on the market. In addition, Hitachi only allow specially selected knife makers to use this special steel because they only want products of the the highest quality to be associated with this brand of steel.

R-2 / SG-2 (Super Gold No.2) / SGPS (Super Gold Powdered Steel)
   SG-2 steel is made for Takefu Special Steel Co., Ltd. by Kobelco (Kobe Steel Group), who also sell the same steel under their own brand as R-2 steel. SG-2 has become a popular steel for knives because of its jaw-dropping cutting performance, excellent edge retention and high corrosion resistance. Thankfully, unlike Cowry X and ZDP-189 , kitchen knives made in SG-2 and R-2 steel are far more available on the market.