I wrote this article to break the flow of copy-pasted content about knife steel brands. In the texts that are copied from one site to another, you can find the same mistakes and inaccuracies. I don’t sell knives, but I do use them. Once, in my youth, I was a chef, and I’ve always been interested in this topic. Later, I became an engineer. That’s why you see this text.
Table of Contents
Hardness and strength:
The hardness of steel is not the only aspect to consider when buying a kitchen knife. A type of steel that is too hard without additives that provide impact toughness is impractical, as it chips very quickly. The ideal combination is a blade with high hardness and high strength. For example,steel.Aogami Blueи.ZDP-189are ideal steels for kitchen knives from this perspective.
However, it is important to understand that a real professional chef in a real kitchen is unlikely to work with knives made of Aogami Blue steel, ZDP-189, or other exotic steels. All these “professional knives” made from various exotic alloys are a luxury item for home use, and their main purpose (besides enriching the manufacturers of these knives) is to provide enjoyment in their use, rather than helping the chef earn a living.
That’s exactly why all expensive knives are made with attention to design and appearance. Sometimes it goes to absurd lengths. You won’t be able to find a knife made from high-quality Japanese steel with a “normal” European handle and without all sorts of unnecessary embellishments, like a deliberately rough spine or other decorations meant to add “authenticity.” A simple cook, a guy without a higher education and a high salary, who spends all day standing in heat and/or humidity, really doesn’t need a knife that can’t be dropped, whose handle can’t get wet, and that can be easily stolen.
Rockwell hardness— this is a measure of the hardness of materials, determined according to the test for hardness According to Rockwell. In this test, “hardness” is interpreted as “resistance to localized indentation.” Hardness is determined by the relative depth of indentation of a steel ball, carbide ball, or diamond cone into the surface of the material being tested.
Rockwell hardness is expressed as a dimensionless number measured on a specific scale. There are different scales (A…V) for various types of materials and testing conditions. For example, scale C is widely used for hard materials. сталей Other commonly used scales are R and M. The higher the number on a given scale, the harder the material. Hardness according to the Rockwell scale is recorded, for example, as 61 HRC (61 on the scale).С.hardness according toRockwell 🙂Текст для перевода: ..
With every two degrees of hardness on the Rockwell scale, a knife will hold its edge roughly twice as long. Thus, a knife with a hardness of 52 HRC will stay sharp for about a week, while one with 62 HRC will maintain its sharpness for around 12 months with regular use.
In European knives (Sabatier, Gude, Zwilling, Helkels&Wusthof, Messermeister, etc.), softer steels with low carbon content are used, but they have good impact toughness. In professional European kitchens, it is common to sharpen knives daily or several times a day. Cheap Chinese knives (usually sold in blocks) have a hardness of about 52 HRC. As a result, these knives retain their sharpness worse and need to be sharpened more often than Japanese knives made from harder steel. The most famous Japanese manufacturer of chef’s knives…GlobalIt uses Cromova steel with a hardness of 58 HRC, which is relatively soft compared to other well-known Japanese brands. There are also significant differences among Japanese knives, but they cannot be compared to European knives made from lower-grade steels (<56 HRC).
There are knives fromHenkel (Myabi)with a hardness of 61 or 66 HRC, but these are knives from Japan, produced on behalf ofHenkelSuch manufacturers asCold Steel, Fällknivenи.Spyderco(pocket knife manufacturers) also produce their best knives in Japan.
Currently, there are many manufacturers that produce their knives in China. They import steel from Japan (usually layered steel with VG-10 at the core), which is then processed into kitchen knives by inexpensive Chinese labor. The price is very appealing, but unfortunately, the finishing, polishing, and handle materials often leave much to be desired. The quality is inconsistent. Due to a poor understanding of forging technology, these knives are often improperly hardened and are sharpened on grinding stones without water cooling. This excessively heats the steel and reduces its Rockwell hardness. VG-10 steel in Japanese knives can have a hardness of 60 to 61 HRC. In Chinese knives, this can be much lower, making them no harder than regular knives that cost half the price.
About steel
Carbon steel in general
Carbon steel is defined as a type of steel with a carbon content ranging from 0.05% to 2.1%. However, we often see manufacturers conveniently rebranding anything that is not stainless steel as carbon steel. Carbon is the element that gives a knife its hardness. Other additives often make the steel more resistant to rust or more durable, but this comes at the expense of hardness. The harder the knife, the thinner it can be sharpened and the sharper it can be made. However, this hardness is often accompanied by susceptibility to rust and high brittleness. Therefore, truly good carbon steel represents an ideal balance between a high carbon content and minimal additions of elements such as cobalt, molybdenum, or vanadium.
Carbon steel is a popular choice for heavy-duty knives and more affordable options. In the past, carbon steel was much stronger, more durable, and easier to sharpen than stainless steel. However, this is no longer the case with the advent of modern alloy metallurgy, such as powder steels like VG-10 and SG-2. These high-quality stainless alloys now offer all the advantages, including hardness, impact toughness, and corrosion resistance, and have surpassed the limitations of carbon steel. Carbon steels lack the chromium additive found in stainless steel, making them highly susceptible to corrosion.
Carbon steels contain less carbon than typical stainless steels, but carbon is the primary alloying element. They are more homogeneous than stainless steels and other high-alloy steels, as carbides are present only in very small inclusions in the iron. Generally, the material is slightly harder than standard stainless steel, such as ST-304 (except for high-quality alloys), which allows them to maintain sharper and straighter edges without bending when in contact with hard materials. However, they dull more quickly due to wear because they lack hard inclusions that can withstand friction. This also makes them easier to sharpen but less resistant to chipping. The only advantage that carbon steel currently has over high-quality stainless steel alloys is its production cost. This steel is much cheaper to produce, which is why carbon steel knives are usually not expensive.
You may often find that chefs in cafeterias, restaurants, and meat departments of supermarkets work with knives made of carbon steel, produced from rolled steel (not forged). Firstly, because it’s cheap. In a professional environment, there is no single knife, and for hygiene and time-saving reasons, each type of product has its own knife, which looks similar to the others but is marked with labels like RS – Raw Fish, MV – Cooked Meat, or OS – Raw Vegetables, etc. Only a mentally unstable restaurant owner would buy 7-8 identical luxury knives of each type for every chef. You can observe chefs constantly honing their knives with a honing rod. Professionals don’t see any problem in touching up the cutting edge of their knife with a well-practiced motion before each approach to their workstation. Additionally, a professional chef will never leave a knife to rust; they will wash it, wipe it down, lightly oil it with unsalted food fat, and place it back in its designated spot, marked just like the knife, for example, “RV – Cooked Fish.”
With constant sharpening, carbon steel knives wear down, and the blade becomes thin, gradually thickening towards the handle. This has led to a consumer stereotype that knives of this shape are considered “sharper.” Knives that are pre-manufactured in this shape are marketed as “boning knives,” although the only requirements for a boning knife are a short length combined with some flexibility in the blade, which makes boning easier. In reality, a heavily sharpened knife (or a knife that has been influenced by marketing) is only suitable for boning, as it can no longer lay flat against a cutting board. If you Google images for the search term “boning knife,” you’ll see the difference between a normal boning knife, which is short and thin, and a “smoker’s boning knife,” which looks like a sharpened knife with an inappropriate and technologically inexplicable bolster at the heel of the blade.
Stainless steel in general
Stainless steel is a collective term for all types of steel that contain no more than 1.2% carbon and at least 11% chromium. Because of this addition of chromium, the likelihood of rust formation is significantly reduced. The addition of chromium also affects the hardness of the steel. However, to make this steel suitable for use as knife steel, elements such as vanadium, molybdenum, titanium, nitrogen, or silicon have been added. This often makes the steel harder and more wear-resistant.
A carbon steel kitchen knife and the maintenance that comes with it are not for everyone. That’s why choosing stainless steel is not a bad option. Today, there are stainless steels that are harder and more wear-resistant than some carbon steels. Stainless steel kitchen knives are easier to maintain, but there is always a risk of rust.
Super stainless steel
Steels of this category have a much higher resistance to staining and corrosion compared to regular stainless steels. These steels are austenitic and non-magnetic. They are used in knives designed for use in aggressive, highly corrosive environments, such as saltwater, and in areas with high humidity, like tropical forests, swamps, etc. These steels can contain between 26% and 42% chromium, as well as 10% to 22% nickel and 1.5% to 10% titanium, tantalum, vanadium, niobium, aluminum, silicon, copper, or molybdenum, among others, or their combinations.
- H1 production by Myodo Metals, Japan. It is used by Spyderco in their knives for saltwater and diving. Benchmade also used it, later replacing it with X15TN.
- X15Tn, a French steel patented by Aubert & Duval, was originally developed for the medical industry and ball bearings for jet engines. According to the company’s specifications, it meets the EN 1.4123 standard (designated as X40CrMoNV16-2) and UNS42025. This is a martensitic stainless steel with a high nitrogen content, remelted to achieve optimal structure and properties. It is used by Benchmade in their knives designed for saltwater and diving.
- Vanax, produced by Uddeholm, is a relatively new 3rd generation powder metallurgy blade steel, in which carbon is largely replaced by nitrogen. As a result, it offers exceptional corrosion resistance, excellent edge retention, and is relatively easy to re-sharpen. It contains a relatively high volume of carbides to maintain an abrasive cutting edge.
- LC200N (also known as Z-FiNit, Cronidur30, N360), produced by Zapp Precision Metals, is a nitrogen-rich tool steel that exhibits excellent corrosion resistance combined with high impact toughness, even at hardness levels up to 60 HRc. Spyderco uses this steel in several of its knives.
Damascus steel
Damascus steel is not actually a type of steel, but it has become very popular and is increasingly used for making kitchen knives. Damascus steel typically consists of two different types of steel with varying carbon content. These two types of steel are alternately forged together. After forging, the blade is etched, causing the high-carbon steel to darken while the low-carbon steel remains light. This creates a nice contrast, making all the layers clearly visible.
Alloying additives
- increases edge retention and enhances tensile strength.
- increases hardness and improves wear and abrasion resistance.
- reduces plasticity as the quantity increases
- provides hardenability.
- increases hardness, tensile strength, and impact toughness.
- increases resistance to corrosion, heat, and wear.
- More than 11% makes the steel “stainless,” causing the formation of an oxide layer.
- Carbide inclusions reduce wear, but the material itself becomes softer.
- increases strength and hardness, allows for hardening at higher temperatures.
- enhances the individual effects of other elements in more complex steels.
- increases resistance to heat and corrosion.
- increases corrosion resistance.
- increases hardenability, wear resistance, and tensile strength.
- It deoxidizes and degasses to remove oxygen from the molten metal.
- in large quantities increases hardness and brittleness.
- It increases or decreases corrosion resistance depending on the type and grade of steel or stainless steel.
- increases strength, hardness, hardenability, and impact toughness.
- improves machinability and corrosion resistance.
- Adds stiffness.
- Increases corrosion and thermal resistance.
- Reduce hardness.
- Excessive presence prevents hardening during heat treatment.
- Limits the growth of carbide grains.
- Increases processability.
- Creates the hardest carbide.
- Increases strength, heat resistance, corrosion resistance, and impact toughness.
- Replaces carbon in the crystal lattice. The nitrogen atom will function similarly to the carbon atom but offers unusual advantages in corrosion resistance.
- Improves strength, machinability, and hardness.
- Increases brittleness at high concentrations.
- Increases strength, heat resistance, and corrosion resistance.
- It deoxidizes and degasses to remove oxygen from the molten metal.
- Improves processability when added in small amounts.
- It is usually considered a pollutant.
- Increases corrosion and heat resistance, strength, plasticity, and impact toughness.
- It adds strength, impact toughness, and improves hardenability.
- Maintains hardness at elevated temperatures.
- Increases corrosion and thermal resistance.
- increases strength, impact toughness, heat resistance, and corrosion resistance, while also reducing weight.
- increases hardness and wear resistance if nitrogen or carbon is present on the surface of the alloy.
- Increases strength, wear resistance, and enhances impact toughness.
- Improves corrosion resistance by promoting the formation of an oxide coating.
- Carbide inclusions are very hard.
- Dear.
- Increases chip resistance.
Stainless and carbon steel for knives
Stainless steel for knives is not as good as carbon steel for powder metallurgy knives. I will explain why, as well as what tricks in steel design can be used to make stainless steel knives just as good as their carbon steel counterparts.
What is stainless steel?
The definition of stainless steel is surprisingly vague. Sometimes a minimum amount of chromium is specified, such as 10.5%, 11%, or 12% (depending on what you read). Chromium forms an oxide layer on the surface of the steel that prevents rusting. However, these definitions usually refer to low-carbon stainless steel. In the world of tool steels and stainless knife steels, the influence of other elements is very important. A common example is D2 steel, which has about 12% chromium but is not considered stainless because its high carbon content leads to the formation of many chromium carbides. When chromium is in the form of carbide, it cannot form an oxide on the surface because it is already bonded with carbon.
Stainless steel is preferred for knives because it requires less maintenance to prevent rust. However, even ignoring cosmetic and maintenance issues, the edges can lose their sharpness due to corrosion. In particular, large knife companies that produce mass-market knives tend to use stainless steels, as the average consumer expects a knife to be made of stainless steel.
Carbon steel vs. stainless steel
Sometimes, among knife enthusiasts, any steel that is not stainless is referred to as “carbon steel.” However, carbon steel specifically refers to a particular category of steels that are alloyed only with carbon, manganese, and silicon. These include steels like 1084, 1095, W1, and White #1. Steels with some addition of alloying elements are called “alloy steels,” including 52100 and 5160. Steels with even greater amounts of alloying elements are referred to as “tool steels,” and sometimes “high-alloy tool steels,” which essentially includes any other non-stainless tool steel, such as A2, D2, CPM-10V, Vanadis 8, etc. Some steels fall somewhere in between, as they are designated as tool steels, like O1 or L6, although I would classify these grades as alloy steels. Even W1, which is a tool steel, can also be considered a simple carbon steel.
Comparison of the compositions of certain steels
| Steel. | C. | Mn. | Si. | Cr. | Mo. | V. | W. | Co. | Ni. |
|---|---|---|---|---|---|---|---|---|---|
| Carbon steels | |||||||||
| 1084. | 0.84. | 0.75. | 0.3. | ||||||
| 1095. | 0.95. | 0.4. | 0.3. | ||||||
| W1. | 1. | 0.25. | 0.25. | ||||||
| White #1 | 1.3. | 0.25. | 0.15. | ||||||
| Alloyed steels | |||||||||
| 52100. | 1.05. | 0.35. | 0.25. | 1.5. | |||||
| 15N20. | 0.75. | 0.4. | 0.25. | 2. | |||||
| 5160. | 0.6. | 0.85. | 0.25. | 0.8. | |||||
| Low-alloy tool steels | |||||||||
| O1. | 0.9. | 1.25. | 0.3. | 0.5. | 0.5. | ||||
| L6. | 0.75. | 0.7. | 0.25. | 0.8. | 0.3. | 1.5. | |||
| High-alloy tool steels | |||||||||
| A2. | 1. | 0.85. | 0.25. | 5.25. | 1.1. | 0.25. | |||
| D2. | 1.5. | 0.3. | 0.3. | 12. | 0.9. | 0.8. | |||
| CPM-10V | 2.45. | 0.5. | 0.9. | 5.25. | 1.3. | 9.75. | |||
| Vanadis 8 | 2.3. | 0.4. | 0.4. | 4.8. | 3.6. | 8. | |||
| High-speed steels | |||||||||
| M2. | 0.85. | 0.3. | 0.3. | 4.25. | 5.5. | 2. | 6. | ||
| M4. | 1.3. | 0.3. | 0.3. | 4. | 4.5. | 4. | 5.5. | ||
| Maxamet | 2.15. | 0.3. | 0.25. | 4.75. | 6. | 13. | 10. | ||
| S390. | 1.64. | 0.3. | 0.6. | 4.8. | 2. | 4.8. | 10.4. | 8. | |
| Rex 45 | 1.3. | 0.3. | 0.5. | 4.05. | 5. | 3.05. | 6.25. | 8. | |
| Rex 121 | 3.4. | 0.5. | 0.4. | 4. | 5. | 9.5. | 10. | 9. |
Comparison of the compositions of certain steels
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These different categories deserve discussion because, although CPM-10V and 1095 are not stainless steels, their properties are quite different. 1095 requires water quenching or fast oil quenching to achieve full hardness, while 10V can be air-cooled and still gain its hardness. The 1095 steel contains iron carbides known as cementite, which provide some wear resistance, although their quantity is relatively small. The relatively low hardness of cementite and its small volume in 1095 means that wear resistance is not particularly high. In contrast, 10V has a significant amount of high-hardness vanadium carbide, which means that 10V has very high wear resistance. 1095 is easy for blacksmiths to work with due to its low alloying content, while 10V will be just as difficult to work with as any stainless steel.
In other words, “carbon steel” is not just a simple group of steels; it encompasses a wide range of properties, and the debates about “stainless steel versus carbon steel” are an oversimplified discussion.
Design limitations
High-speed steels require the addition of large amounts of Mo and/or W to ensure “hot hardness” for tools operating at high speeds, where heat is generated. Mo/W means that the steel resists softening when heated. However, the requirement for high Mo/W is a design constraint in terms of maximizing other properties. Without the required Mo/W, it could be possible to better optimize impact toughness and wear resistance. The same applies to stainless steel, which requires a significant amount of chromium. Adding any other design requirement means that we are likely to limit properties in some other area. For knife steels, a combination of high hardness, impact toughness, and wear resistance is required.
Strength and wear resistance
One set of properties that are usually opposite to each other is impact toughness and wear resistance. Wear resistance is determined by the hardness of the steel, the hardness of the carbides in the steel, and the quantity of carbides. Higher hardness, harder carbides, and a greater number of carbides improve wear resistance. Greater wear resistance means that edge wear occurs more slowly, ensuring better edge retention. Here is a diagram summarizing the hardness of various types of carbide:
Types of Carbides
| Type of carbide | Formula | Hardness (Vickers) | Hardness (Rc) |
|---|---|---|---|
| Iron | Fe.3.O.4. | 1000. | 69. |
| Chromium No. 1 | Cr.23.C.6. | 1200. | 72. |
| Molybdenum/Tungsten | M.6.C. | 1400. | 75. |
| Chromium No. 2 | Cr.7.C.3. | 1500. | 76. |
| Chromium nitride | CrN/Cr2.N. | 1700. | 78. |
| Chromium-Vanadium | CrV.7.C.3. | 1950. | 81. |
| Tungsten | WC. | 2600. | 86. |
| Niobium | NbC. | 2600. | 86. |
| Vanadium | VC. | 2800. | 87. |
A diagram summarizing the hardness of various types of carbide.
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Vanadium carbides are among the hardest of all types of carbides, which is why steels with a high vanadium content often exhibit the best wear resistance and edge retention.
From a strength perspective, however, having more carbide is not good. Carbides are hard and brittle, which makes cracks more likely to form. This leads to easier chipping, breaking of knife tips, and so on.
Thus, we have a fundamental dichotomy between wear resistance and impact toughness. More carbide means better wear resistance, but also lower impact toughness. However, the hardness of the carbide usually does not affect impact toughness. Therefore, if we use harder carbides (such as vanadium carbide) and keep their sizes small, we achieve greater wear resistance for a given amount of carbide and, consequently, higher wear resistance for a given level of impact toughness. Thus, steels with the best combination of impact toughness and wear resistance are typically powder metallurgy steels (the carbides must be small) that are primarily alloyed with vanadium carbides. Such steels include CPM-1V, CPM-3V, Vanadis 4 Extra, CPM-4V, CPM-10V, K390, and Vanadis 8.
Why is stainless steel worse?
When we add a lot of chromium, it becomes harder to ensure that all the carbides are vanadium carbides. Instead, a high chromium content leads to the formation of chromium carbides, which are softer than vanadium carbide and result in a poorer combination of impact toughness and wear resistance. A higher chromium content means less vanadium carbide for a given amount of vanadium, and of course, a higher chromium content means more chromium carbide.
Another problem with chromium carbides is that in powder metallurgy steels, they are larger than vanadium carbides. As explained earlier, larger carbides lead to lower impact toughness. In powder metallurgy, the carbide size is initially very small, but it increases due to a natural process called Ostwald ripening. The higher the temperature, the faster the carbide growth occurs. During the powder consolidation process (hot isostatic pressing or HIP), as well as during forging and rolling, the steel is subjected to high temperatures where carbides grow slowly. Chromium carbides are less stable than vanadium carbides, which leads to faster coarsening. This is why CPM-D2 (chromium carbide) has larger carbides than Vanadis 8 (vanadium carbides), even though both contain the same amount of carbide.
Comparison of stainless steel and non-stainless steel
Add more carbon and vanadium to stainless steels (more hard carbides), and you will definitely be able to maintain the cutting edge better by reducing impact toughness.
However, the properties of powder metallurgy stainless steels are significantly better. The impact toughness of powder metallurgy stainless steels nearly doubles at a given edge retention level. This means that the edges are less likely to chip, higher hardness levels can be used without compromising strength, and/or the edges can be ground thinner for better cutting performance due to the higher impact toughness and hardness.
The problem is that all powder stainless steels contain a significant amount of chromium carbide, at least 9-10%, and at least 15% total carbide. The presence of more than 15% carbide means that impact toughness is unlikely to be high. The high overall carbide content and the presence of chromium carbides, which reduce the balance of strength and edge retention compared to all vanadium carbides, indicate that powder stainless steels are not as good as some powder high-carbon steels. Powder stainless steels such as 3V, CPM-CruWear, Vanadis 4 Extra, and CPM-M4 have a very attractive combination of properties due to their high impact toughness at a given level of edge retention.
What can be done?
One way to improve properties is by reducing the amount of chromium, so that instead of chromium carbide, vanadium carbide is formed. This does not necessarily mean a decrease in corrosion resistance. S110V, with 15.25% chromium, has the same level of corrosion resistance as M390, which contains 20% Cr, because the overall composition matters, not just the Cr content. Most knife steels contain 10-13.5% Cr “in solution,” which contributes to corrosion resistance. Thus, M390, with 20% Cr, has only about 13% in solution, while the rest is bound in carbides. These facts were utilized in the development of 14% Cr S90V back in 1995 to enhance the properties of vanadium-alloyed powder metallurgy steels compared to earlier steels with 16-20% Cr. This base Cr content of 14% was also used in the creation of S30V, S35VN, and S125V. Another beneficial aspect is the use of molybdenum alloying, which increases corrosion resistance at a given level of chromium content, which is why grades S30V, S35VN, S125V, S110V, and S45VN contain 2% or more Mo. S35VN has excellent corrosion resistance compared to S90V, even though both contain 14% Cr, because S35VN has a higher Mo content.
On the other hand, CPM-3V and CPM-CruWear have very good properties, despite a slightly higher chromium content (7.5%). Typical rusting steels contain 4-5.5% Cr, so we know that a somewhat higher Cr content can still lead to very good properties. Almost all of the chromium in CPM-3V is in solution, which makes it more corrosion-resistant than D2 (a rusting steel known for its good corrosion resistance). CPM-CruWear contains some amount of chromium carbide, but the quantity is small enough not to negatively affect its impact toughness. 3V and CruWear are very similar steels, aside from their carbon content, which further emphasizes the importance of carbon levels. CPM-CruWear has a slightly higher hardness than 3V, but its impact toughness and corrosion resistance are reduced due to the presence of chromium carbides.
| Steel. | C. | Cr. | V. | Mo. | W. |
|---|---|---|---|---|---|
| 3V. | 0.8. | 7.5. | 2.75. | 1.3. | |
| CruWear | 1.1. | 7.5. | 2.4. | 1.6. | 1.15. |
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Thus, with examples of improved properties of stainless steels with reduced Cr content (14%), and on the other hand, with stainless steels that have very good properties with 7.5% Cr (along with a balanced carbon content), it should be possible to develop steels with intermediate Cr content. If the overall composition (especially carbon) is balanced in combination with 10-13% Cr, all the chromium can be dissolved during heat treatment, leaving only vanadium carbides, resulting in stainless steels with properties as excellent as those of powder stainless steels. Experiments will be needed to find the limit in terms of chromium content at which carbon can be balanced so that all chromium carbide dissolves during heat treatment. Molybdenum additions will also help improve corrosion resistance at a given amount of chromium.
Creating stainless steels without powder metallurgy
Another way to design stainless steels is to maintain a very low carbide content, so that the chromium carbides remain small and the impact toughness is high. The best examples of this approach are AEB-L, 12C27, and 14C28N. These steels have lower wear resistance and edge retention compared to powder stainless steels, but they also offer significantly better impact toughness and a very fine microstructure. Metallurgists have achieved this by carefully balancing the carbon and chromium content to achieve high hardness and corrosion resistance without forming a large amount of chromium carbide.
Steels like AEB-L and 14C28N have relatively low edge retention, but they still outperform low-alloy steels such as 52100 and 1095 because the chromium carbides are harder than the iron carbide (cementite) found in low-alloy steels. Thus, in this case, stainless steel actually offers a better balance of properties than “carbon steel.” Again, this is why the debate of “stainless steel versus carbon steel” is overly simplistic. It all depends on which stainless steels you are referring to and in what category of properties.
Niobium alloying
These low carbide stainless steels can also exhibit increased wear resistance with a slight reduction in impact toughness by adding a small amount of vanadium or niobium for better edge retention. The closest available steel for this approach is Niolox, but unfortunately, its carbide size is relatively large, which means the impact toughness is not as good as one might hope. The largest carbides in Niolox are chromium carbides, so it may be possible to reduce the carbide size with more careful design. Niobium is a “stronger” carbide former than vanadium, meaning it can form niobium carbides even in the presence of large amounts of chromium.
Niobium alloying in powder steels
Since niobium carbides are more stable than vanadium carbides, they also coarsen more slowly during HIP, hot rolling, etc. This means that niobium carbides are even smaller than vanadium carbides in the finished steel. This was observed during the development of a modified version of CPM-3V that used primarily niobium alloying instead of vanadium. It was found that the carbide size decreased and impact toughness improved in the niobium version. This modified 3V was never produced in series.
| Steel. | C. | Cr. | V. | Mo. | W. |
|---|---|---|---|---|---|
| 3V. | 0.8. | 7.5. | 2.75. | 1.3. | |
| CruWear | 1.1. | 7.5. | 2.4. | 1.6. | 1.15. |
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Limits of niobium content in powder metallurgy steels
3V was a good candidate for producing a niobium-modified version because it has a relatively small volume of carbide and, therefore, a relatively small amount of niobium required. Since niobium is such a “strong” carbide former, it tends to form carbides at high temperatures even in liquid steel. The more niobium is added, the higher the temperature at which carbides form. With a certain amount of niobium, carbides form in the liquid steel before it can be atomized (solidified) into powder. This leads to the formation of large carbides, as carbide growth occurs rapidly at such high temperatures and in a liquid state. This can even lead to clogging of the “nozzle,” where the liquid steel passes through jets of gaseous nitrogen. Typically, this limits the amount of niobium added to about 3% or so. However, there is a Bohler patent for high-niobium powder steels that are first atomized without the addition of carbon, so instead of niobium carbide, FeNb is formed. The powder is then mixed with graphite (carbon) before being pressed into a solid ingot.
| Steel. | C. | Cr. | Mo. | V. | N. | Nb. |
|---|---|---|---|---|---|---|
| M390. | 1.9. | 20. | 1. | 4. | 0.2. | |
| Patented | 1.45. | 12. | 2.2. | 0.2. | 9. |
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In one of the compositions, only 12% Cr was added (as mentioned in the “Patented” section), but with the use of niobium and the appropriate carbon content, most of the chromium remained in solution after heat treatment. They found improved corrosion resistance compared to M390, despite the relatively low chromium content, likely partly due to the increased molybdenum content (combined with all the chromium being in solution). There was also enhanced wear resistance due to the high niobium content. However, the patent application was first filed in 2009, and we still don’t have any products, so I’m not sure if they will ever be released.
Partial replacement of vanadium with niobium
The use of partial replacement of vanadium with niobium can also reduce the size of carbides, improving impact toughness and corrosion resistance.
| Steel. | C. | Cr. | Mo. | V. | N. | Nb. |
|---|---|---|---|---|---|---|
| S110V. | 2.8. | 15.25. | 2.25. | 9. | 3. | 2.5. |
| S125V. | 3.3. | 14. | 2.5. | 12. |
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Nitrogen alloying
Nitrogen has been used in certain amounts in several knife steels, such as S30V, which was released in 2001 with a nitrogen content of about 0.2%. Another example is Cronidur 30/LC200N, which contains 0.4% nitrogen and was developed in the late 1980s for bearings but has since found applications in knives. More recently, a steel called Vanax was developed using a special powder metallurgy process with a high nitrogen content of 1.55%. Liquid steel has relatively low nitrogen solubility, so they spray the steel with a relatively low nitrogen content. They then nitrify the steel powder to add nitrogen before the HIP process to create a billet.
Chromium and vanadium nitrides coarsen more slowly than their carbide counterparts. Additionally, nitrogen does not reduce corrosion resistance to the same extent as carbon. When particles contain both carbon and nitrogen, they are referred to as “carbonitrides,” rather than carbides (carbon) or nitrides (nitrogen). The improved particle size compared to earlier steels can be seen by comparing Uddeholm Elmax with Vanax. These two steels are very similar, except that Vanax contains 1.55% nitrogen and 0.35% carbon, while Elmax contains 1.7% carbon and approximately 0.1% nitrogen. Despite the relatively high amount of carbonitrides in Vanax, its impact toughness is still not particularly high. However, it may be possible to develop modified steels with a reduced volume of carbide/nitride to improve the balance between impact toughness and edge retention. Vanax still contains about 10% chromium carbide/nitride and 4% vanadium carbonitride, which makes the total volume of carbide/nitride comparable to that in other stainless steels. Regarding chromium carbonitrides, about 14-15% Cr is in solution in Vanax, which suggests that it should be possible to reduce the Cr content to around 14% and restore the balance of carbon and nitrogen so that chromium carbonitrides dissolve during heat treatment. This would help maintain Vanax’s high corrosion resistance while simultaneously improving the balance between strength and edge retention.
| Steel. | C. | N. | Cr. | Mo. | V. |
|---|---|---|---|---|---|
| Vanax. | 1.55. | 0.35. | 18.2. | 1.1. | 3.5. |
| Elmax. | 1.7. | 0.1. | 18. | 1. | 3. |
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The influence of niobium and nitrogen on chromium carbide
Both nitrogen and niobium can also be used to reduce the amount of chromium carbide formed. Nitrogen is less prone to forming chromium nitrides than carbon is to forming chromium carbides. Both nitrogen and carbon increase the hardness of steel. Thus, carbon can be partially replaced by nitrogen to maintain a similar level of hardness while achieving better corrosion resistance and improved impact toughness due to the reduced amount of chromium carbide. Niobium, being a stronger carbide former than vanadium, means that replacing vanadium with niobium results in less chromium carbide formation. Vanadium leads to a greater amount of chromium carbide, while niobium does not. These two elements can also be used in combination, as seen in S45VN, which contains 0.5% Nb and approximately 0.17% nitrogen. This means that S45VN has not much more chromium carbide than S30V or S35VN, despite containing 16% rather than 14% chromium. The use of these two elements has also led to an improved microstructure in S45VN (Nb+N) compared to S30V (0.2% N, no Nb) or S35VN (0.5% Nb, with low N content). The new exclusive Spyderco steel CPM-SPY27 also contained a combination of Nb and N along with a reduced Cr content (14%), resulting in a somewhat lower amount of chromium carbide, but the steel still has many carbide “clusters,” which means the average carbide size is larger than that of powder stainless steel containing only vanadium. The chromium carbide content would need to be even lower for a real improvement in properties compared to modern powder stainless knife steels.
| Steel. | C. | N. | Cr. | Mo. | V. | Nb. | Co. |
|---|---|---|---|---|---|---|---|
| S30V. | 1.45. | 0.2. | 14. | 2. | 4. | ||
| S35VN. | 1.35. | 0.05. | 14. | 2. | 3. | 0.5. | |
| S45VN. | 1.48. | 0.17. | 16. | 2. | 3. | 0.5. | |
| SPY27. | 1.25. | 0.12. | 14. | 2. | 2. | 1. | 1.5. |
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Summary and conclusions
The most effective steels for knives are rusting steels alloyed with vanadium, produced using powder metallurgy. However, we would prefer to have a steel for knives that is also stainless, as this requires less maintenance to avoid rust and reduces the likelihood of losing sharpness due to corrosion. The requirement to add a large amount of chromium compromises the properties by replacing vanadium carbides with chromium carbides. Chromium carbides are softer, which decreases wear resistance, and they are larger, which reduces impact toughness. Softer carbides also mean that for a given edge retention, more carbides are needed, further decreasing impact toughness. To improve the properties of stainless steel for knives, we need to minimize the amount of chromium carbide and instead favor hard carbides, such as vanadium and niobium carbides. This is a complex balance, but there are several examples of steels that provide enhanced properties. Reducing the chromium content in combination with a balanced composition, especially of carbon, can lead to a significant reduction in the volume of chromium carbide. Alloying with nitrogen and niobium can also reduce the overall carbide size to approach the properties of powder rusting steels. By applying what we have learned about knife steel design over the past 30 years or so, we can find several different ways to improve stainless knife steel, and we hope to see these developments in the future. Alloying with nitrogen and niobium can also reduce the overall carbide size to approach the properties of powder rusting steels.
Steel grades
Steel is available in many types and compositions. From a technical standpoint, such things asstainless steel does not exist.All steels rust if not properly treated. Some steels resist corrosion better than others. The best term is the English term “stainless steel,” which means steel that does not stain. Essentially, chromium provides rust resistance; knives with a chromium content of 11% or more have good rust resistance. In this document and elsewhere on this site, the term “stainless” should be understood to mean “stain-resistant.” Additionally, there is a correlation between hardness (measured on the Rockwell C scale (HRC)) and impact toughness. Steel manufacturers are always looking for the optimal balance between hardness and impact toughness. Complex alloys and exotic materials added to steel primarily serve to enhance its impact toughness.
It is also important to understand that the method of forging and tempering can affect hardness. Thus, there are differences in hardness between knife manufacturers. A well-known example isShirogami White Steel #1This traditional very pure Japanese steel is not particularly strong, but it can undergo extremely aggressive hardening, so its hardness ranges from 60 to 65 HRC.
Table of some types of steel
| Brand. | Hardness (HRC) | Country | C. | Cr. | Mo. | V. | Mg. | Ni. | Si. | Co. | Cu. | P. | N. | Nb. | W. |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1095. | 56-59. | USA. | 0,9-1,03 | —. | —. | —. | 0,3-0,5 | —. | —. | —. | —. | —. | —. | —. | —. |
| 12C27. | 57-59. | Sweden | 0.58. | 14. | —. | —. | 0.35. | —. | 0.35. | —. | —. | —. | —. | —. | —. |
| 14C28N | 55-62. | Sweden | 0.62. | 14. | —. | —. | 0.6. | 0.2. | 0.03. | 0.11. | |||||
| 154CM. | 58-59. | USA. | 1.05. | 14. | 4. | 0.4. | —. | 0.35. | —. | —. | —. | —. | —. | —. | |
| 3Cr13MoV | 52-55. | China. | 0,26-0,4 | 2014-12-01 00:00:00 | —. | —. | 1. | —. | —. | —. | —. | 0.04. | —. | —. | —. |
| 4034. | 54-55. | Germany | 0,42-0,5 | 12,5-14,5 | —. | —. | 1. | —. | 1. | —. | —. | —. | —. | —. | —. |
| 40X10C2M | 57-58. | Russia | 0.45. | 10. | 0,7-0,9 | 0.2. | 0,5-0,7 | 0.6. | 1,9-2,6 | —. | 0.3. | 0.03. | —. | —. | —. |
| 4116. | 55-56. | Germany | 0,45-0,55 | 14-15. | 0,5-0,8 | 0,1-0,2 | 0. | —. | 0. | —. | —. | —. | —. | —. | —. |
| 420. | 54. | USA. | 0,4-0,5 | 2014-12-01 00:00:00 | —. | —. | —. | —. | —. | —. | —. | —. | —. | —. | —. |
| 440A. | 56. | USA. | 0,6-0,75 | 16-18. | 0.75. | —. | 1. | —. | 1. | —. | —. | —. | —. | —. | —. |
| 440B. | 56. | USA. | 0,75-0,95 | 16-18. | 0.75. | —. | 1. | —. | 1. | —. | —. | —. | —. | —. | —. |
| 440C. | 58. | USA. | 0,95-1,2 | 16-18. | 0.75. | —. | 1. | —. | 1. | —. | —. | —. | —. | —. | —. |
| 5160. | 56-59. | USA. | 0,56-0,64 | 0,7-0,9 | —. | —. | 0,75-1 | —. | 0,15-0,3 | —. | —. | 0.04. | —. | —. | —. |
| 5Cr15MoV | 55-56. | China. | 0.45. | 15. | 0.5. | —. | 1. | —. | 1. | —. | —. | —. | —. | —. | —. |
| 8Cr13MoV | 58-60. | China. | 0.8. | 13. | 0.15. | 0.1. | 0.4. | 0.2. | 0.5. | —. | —. | 0.02. | —. | —. | —. |
| 95X18. | 57-58. | Russia | 0,9-1,1 | 17-19. | —. | —. | 0.8. | 0.6. | 0.8. | —. | 0.3. | 0.03. | —. | —. | —. |
| 9Cr18MoV | 56-58. | China. | 0,9-1,05 | 16-19. | —. | —. | 0.8. | —. | 0.8. | —. | —. | 0.03. | —. | —. | —. |
| Acuto+ | 59-60. | 0,9-0,95 | 17-18. | 1,3-1,5 | 0,1-0,25 | 0.5. | —. | 0.5. | —. | —. | 0.04. | —. | —. | —. | |
| ATS-34 | 58-59. | Japan | 1.05. | 14. | 4. | —. | 0.4. | —. | 0.35. | —. | —. | —. | —. | —. | —. |
| AUS-4. | 55-57. | Japan | 0,4-0,45 | 13-14,5 | —. | —. | 1. | 0.4. | 1. | —. | —. | 0.4. | —. | —. | —. |
| AUS-6 (= 6A) | 56-57. | Japan | 0,55-0,65 | 13-14,5 | —. | 0,1-0,25 | 1. | —. | 1. | —. | —. | —. | —. | —. | —. |
| AUS-8 (= 8A) | 57-58. | Japan | 0,7-0,75 | 13-14,5 | 0,1-0,3 | 0,1-0,25 | 1. | —. | 1. | —. | —. | —. | —. | —. | —. |
| C75. | 55-58. | Germany | 0,7-0,8 | —. | —. | —. | 0,6-0,8 | —. | 0,15-0,35 | —. | —. | 0.04. | —. | —. | —. |
| CPM-10V | 60-64. | USA. | 2.45. | 5.25. | 1.3. | 9.75. | 0.5. | 0.9. | —. | —. | —. | —. | —. | —. | |
| CPM-3V | 62-63. | USA. | 0.8. | 7.5. | 1.3. | 2.75. | —. | —. | —. | —. | —. | —. | —. | —. | —. |
| CPM-D2 | 59-61. | USA. | 1.55. | 11.5. | 0.9. | 0.8. | —. | —. | —. | —. | —. | —. | —. | —. | —. |
| CPM-M4 | 60-62. | USA. | 1.4. | 4. | 5.25. | —. | 0.3. | —. | 0.55. | —. | 0.06. | —. | —. | —. | 5.5. |
| CPM-S-30V | 58. | USA. | 1.45. | 14.5. | 2. | 4. | —. | —. | —. | —. | —. | —. | —. | —. | —. |
| CPM-S-35VN | 59-60. | USA. | 1.38. | 14. | 2. | 3. | 0.5. | —. | 0.5. | —. | —. | —. | 0.05. | 0.5. | —. |
| CPM-S-60V | 57-58. | USA. | 2.15. | 17.5. | 0.5. | 5.75. | 0.5. | —. | 0.5. | —. | —. | —. | —. | —. | —. |
| CPM-154 | 58-61. | USA. | 1.05. | 14. | 4. | —. | 0.5. | —. | 0.3. | —. | —. | —. | —. | —. | —. |
| Cronidur-30 | 58-60. | Germany | 0,25-0,35 | 14-16. | 0,85-1,1 | —. | 0-1. | 0-0.5. | 0-1. | —. | —. | —. | 0,3-0,5 | —. | —. |
| CTS 204P | USA. | 1.9. | 20. | 1. | 4. | 0.3. | —. | 0.6. | —. | —. | —. | —. | —. | —. | |
| CTS 20CP | USA. | 2.2. | 13. | 1.3. | 9.3. | 0.5. | —. | 0.9. | —. | —. | —. | —. | —. | —. | |
| CTS 40CP | USA. | 1.7. | 18. | 1. | 3. | 0.3. | —. | 0.8. | —. | —. | —. | —. | —. | —. | |
| CTS B52 | USA. | 0,98-1,1 | 1,3-1,6 | —. | —. | 0,25-0,45 | —. | 0,15-0,3 | —. | —. | —. | —. | —. | —. | |
| CTS B75P | USA. | 1,1-1,2 | 14-15. | 3,8-4,2 | 1-1.5. | 0.5. | —. | 0.3. | —. | —. | —. | —. | —. | —. | |
| CTS BD-1 | USA. | 0.9. | 15.5. | 0.3. | 0.1. | 0.6. | —. | 0.37. | —. | —. | —. | —. | —. | —. | |
| CTS BD-30P | USA. | 1.5. | 14. | 2. | 4. | 0.5. | —. | 0.3. | —. | —. | —. | —. | —. | —. | |
| CTS XHP | USA. | 1.6. | 16. | 0.8. | 0.45. | 0.5. | 0.35. | 0.4. | —. | —. | —. | —. | —. | —. | |
| D2. | 59-61. | USA. | 1.5. | 12. | 1. | 1. | 0.6. | 0.3. | 0.6. | —. | —. | —. | —. | —. | —. |
| Elmax. | USA. | 1.7. | 18. | 1. | 3. | 0.3. | —. | 0.8. | —. | —. | —. | —. | —. | —. | |
| GIN-1. | 56-58. | Japan | 0.9. | 15.5. | 0.3. | —. | 0.6. | —. | 0.37. | —. | 0.03. | 0.02. | —. | —. | —. |
| H1. | 58-59. | Japan | 0.15. | 14-16. | 0,5-1,5 | —. | 2. | 2023-08-06 00:00:00 | 3-4.5. | —. | —. | 0.04. | 0.1. | —. | —. |
| N690. | 58-60. | Austria | 1.07. | 17.3. | 1.1. | 0.1. | 0.4. | —. | 0.4. | 1.5. | —. | —. | —. | —. | —. |
| N695. | 57-58. | Austria | 0,95-1,2 | 16-18. | 0.75. | —. | 1. | —. | 1. | —. | —. | —. | —. | —. | —. |
| Niolox (1.4153) | 58-62. | Germany | 0.8. | 12.7. | 1.1. | 0.9. | —. | —. | —. | —. | —. | —. | —. | 0.7. | —. |
| Nitro-B (1.4116N) | 59-60. | Germany | 0.5. | 14.7. | 0.6. | 0.15. | 1. | —. | 1. | —. | —. | <0.04. | 0.15. | —. | —. |
| Nitro-V | 60-63. | Germany – USA | 0.68. | 13. | —. | 0.08. | 0.65. | —. | 0.4. | —. | —. | —. | 0.11. | —. | —. |
| O1. | 61-63. | USA. | 0.95. | 0.5. | —. | 0.2. | 1.2. | —. | 0.4. | —. | —. | 0.3. | —. | —. | 0.5. |
| S70. | 60-62. | USA. | 0,45-0,55 | 3-3.5. | 1,3-1,8 | 0,2-0,3 | 0,2-0,8 | —. | 0.2-1. | —. | —. | —. | —. | —. | —. |
| SGPS. | 62. | Sweden | 1.4. | 15. | 2.8. | 2. | 0.4. | —. | 0.5. | —. | —. | 0.03. | —. | —. | —. |
| SK-5. | 57-60. | Japan | 0.9-1. | —. | 0.3. | —. | —. | —. | 0.3. | —. | —. | —. | —. | —. | —. |
| SK-85. | 57-60. | Japan | 0,8-0,9 | 0 -0,3 | —. | —. | 0,1-0,5 | 0-0,25 | 0,1-0,35 | —. | 0-0,25 | 0.03. | —. | —. | —. |
| Sleipner | >60. | Sweden | 0.9. | 7.8. | 2.5. | 0.5. | 0.5. | 0.9. | |||||||
| T6MoV. | 54-56. | France | 0.6. | 14.2. | 0.65. | 0.1. | —. | 0.23. | —. | —. | —. | —. | —. | —. | —. |
| VG-10. | 58-60. | Japan | 0,95-1,05 | 14,5-15,5 | 0,9-1,2 | 0,1-0,3 | 0.5. | —. | 0.6. | 1,3-1,5 | —. | 0.3. | —. | —. | —. |
| VG-2. | 57-58. | Japan | 0,6-0,7 | 13-15. | 0,1-0,2 | —. | 0.5. | 0.15. | 0.5. | —. | —. | 0.03. | —. | —. | —. |
| X-15T.N. | 58. | France | 0.4. | 15.5. | 2. | 0.3. | —. | —. | —. | —. | —. | —. | 0.2. | —. | —. |
| X50CrMoV15 | 55-56. | Germany | 0,45-0,55 | 14-15. | 0,5-0,8 | 0,1-0,2 | 0. | —. | 0. | —. | —. | —. | —. | —. | —. |
| ZDP-189 | 65-67. | Japan | 3. | 20. | —. | —. | —. | —. | —. | —. | —. | —. | —. | —. | —. |
Some types of steel used for kitchen knives
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Steel for Japanese kitchen knives
Various manufacturers produce steel for Japanese kitchen knives. Currently, VG-10 steel is the most widely used in the high-end segment, but several other steel grades from the following manufacturers have also gained popularity:
Takefu Special Steel (Japan)
- VG-MAX (60-62 HRC) — stainless steel
- VG-10 (60-61 HRC) — stainless steel
- VG-5 (60HRC) — stainless steel
- VG-2 (59-60 HRC) — stainless steel
- VG-1 (59-60 HRC) — stainless steel — (similar to VG-10, but without vanadium and cobalt)
- V2 (58-61 HRC) — stainless steel
- V1 (58-59 HRC) — stainless steel
- SG-2 or R2 (62-63 HRC) — stainless steel
Hitachi Steel Ltd (Japan) (“Yasuki Hagane” YSS (Yasuki Specialty Steel))
Not resistant to rust.
- Aogami Super (63-65 HRC)
- Aogami Blue #1 ( Aoko.or Ao ichi ko ) (62-64 HRC)
- Aogami Blue #2 (Ao ni ko) (61-63 HRC)
- Shirogami White #1 (Shiro-Ko 1 or Shiro ichi ko) (60-64 HRC)
- Shirogami White #2 (Shiro-Ko 2 or Shiro ni ko) (60-63 HRC)
- Shirogami White #3 (58-62 HRC)
- Kigami Yellow #1 (60-62 HRC)
- Kigami Yellow #2 (60-62 HRC)
- Kigami Yellow #3 (59-60 HRC)
Rust-resistant:
- ATS-34 (60-61 HRC)
- ZDP-189 (64-67 HRC), 3% carbon and 20% chromium (analogous to Cowry X)
- SLD Magic (60-62 HRC)
- SLD or SKD11 (60-64 HRC)
- Gingami No. 1 to No. 5 (also known as GIN-1 or G1) (58-61 HRC)
As a rule, Shirogami steel can be sharpened to a finer edge, while Aogami steel retains its sharpness longer. For traditional Japanese knives (like Yanagiba, Deba, etc.), Shirogami White #1 is highly recommended. Aogami is the best type of steel for more versatile use. Aogami is somewhat more expensive than Shirogami. In fact, Aogami steel is similar to Shirogami but with some added elements, such as tungsten and chromium. Aogami is known for its high sensitivity to rust, so it’s important to clean and dry knives made from it after each use. Aogami Super, in addition to having a higher carbon content, also contains more tungsten and chromium than Aogami #1, as well as molybdenum and vanadium, making this steel extremely hard yet durable. This steel (along with ZDP-189) can be considered one of the best types of steel for use in kitchen knives.
Types of steelKigami is a bit cheaper thanAogamiили.Shirogami, it is well-suited for kitchen knives.Kigami #2 due to its higher carbon content.
The colors used (white, blue, and yellow) do not indicate the color of the sample. This terminology comes from the manufacturer Hitachi, which supplied steel billets wrapped in paper of different colors to forges. Hence the term “Blue Paper Steel,” or in Japanese “Aogami,” which means nothing more than “steel wrapped in blue paper.”
Often, the manufacturer indicates the type of steel on the blade, and you can check what is specified on your blade.
Daido Special steel
- The relatively soft steel Daido 1K6 (57-58 HRC) is used in budget knives, such as the Kai Wasabi series.
- Cowry-X powdered steel (64-65 HRC) – 3% carbon and 20% chromium, is similar to ZDP-189.
JFE-steel corp.
- SK-5 (57-65 HRC) in kitchen knives is usually around 60 HRC.
- S55C (58-61HRC)
Other Japanese steels
- SRS-15 (63-65 HRC)
- AUS-8 (57-58 HRC)
- AUS-8A (57-59 HRC), also known as “molybdenum-vanadium steel,” is similar to the steel used in the best German knives.
- Chromova 18 (56-58 HRC) (used only for Global knives)
Western steels
- Sandvik 19C27 (Swedish) (60-62 HRC), depending on the heat treatment method.
- Sandvik 13C26 (Swedish)
- MC66 (German) (This is actually Japanese steel ZDP-189)
- S30V (USA)
- CPM™ 154 (USA)
A list with descriptions of commonly used steel grades:
Surgical steelSurgical steel).— is also often referred to asstainless surgical steelThis is steel that is best avoided by taking a long detour. Official grade.there is no surgical steel,It relates to soft steels used in medicine, consisting of alloys such as 17-4, 17-4 PH, stainless steel 455, and implant materials like 316L or titanium 6AL4V (which is not officially classified as steel). None of these steels have the proper properties for knife manufacturing. However, they are very resistant to rust. From a marketing perspective, the term “surgical steel” is used to denote a high-quality product, but in practice, knives labeled as “surgical steel” (420 steel or worse) are the cheapest Chinese junk. Don’t buy them, and if you have any at home, just throw them away.
Series 420— Very wear-resistant and highly rust-resistant, it’s a good choice for use as a diving knife, but not for the kitchen. Its very low carbon content, less than 0.3%-0.5%, makes it too soft for a useful cutting tool in the kitchen. It is mainly used in very cheap kitchen knives.
440A/440BMany of the inexpensive basic kitchen knives (Blokker, Kwantum, etc.) are made from these or similar steels. There are well-known knife manufacturers (Cutco) that use 440A steel in their kitchen knives, but this steel is not strong enough to be used as a cutting material.
440C.— It was once considered a good type of steel (20 years ago), but now this type is outdated and can no longer compete with more modern steels. Nevertheless, there are still many manufacturers that use this type of steel in kitchen knives. If 440C steel is properly heat-treated, it is an excellent type of steel for kitchen knives. If this steel does not undergo good heat treatment, it is completely unsuitable for kitchen knives. Generally, it has good strength and decent rust resistance.
Bohler N690— martensitic, cobalt-alloyed steel produced by Böhler-Uddeholm AG, a metallurgical group and one of the leading global suppliers of high-quality tool steel. They manufacture sheet steel, pipes, wire, forging equipment, gas turbine components, and “FOX” brand welding electrodes. The company has factories in Austria, Germany, North and South America, and sales offices on all continents. It is a joint-stock company, with 25% of the shares owned by the state (Austrian Industrial Holding). It was formed in 1991 as a result of the merger between the state-owned company Böhler Ges.m.b.H. and the Swedish company Uddeholm AB.
The addition of cobalt makes the alloy structure uniform, and this is further enhanced by a unique technology for rolling steel sheets in both longitudinal and transverse directions. The alloy has excellent cutting properties, resists impact loads well, and sharpens beautifully.
In composition, this steel is approximately equivalent to 440C, but it contains more molybdenum and cobalt. It is sometimes referred to as Austrian 440C or Austrian cobalt stainless steel. It is distinguished by its very high corrosion resistance and the ability to be hardened to 60 HRC.
It is considered a good steel for outdoor long knives and tactical knives, which need not only a durable edge but also the ability to withstand impact and lateral loads (during twisting and bending). Many European companies make knives from this steel.
A close equivalent, or analog, of this steel grade is the Japanese VG-10. However, it contains more molybdenum and chromium compared to N690C. Similar compositions and properties can be found in AUS-10 (Japan), French Z100CD17, Swedish Sandvik 12C27, X102CrMo17 (Germany), as well as the Russian steel 95X18. However, all of them fall short in quality compared to Bohler N690 steel.
12С27.— Sandvik production. This is a well-known type of steel that was highly valued in the past. It is Swedish stainless steel that is often used for making razors. The steel can be sharpened to a very fine edge and retains its sharpness well (the duration for which the blade remains sharp). It is an excellent type of steel, but it is not particularly special.
19C27.— it is similar to steel 12C27, but with a higher content of carbon and manganese. This steel is hardened to 60-62 HRC, depending on the manufacturer. Kagemitsu hardens this steel to 61-62, andSuisin tempers.this steel up to 60 HRC. This steel can be sharpened to a very fine edge and retains its sharpness well (the duration for which the blade remains sharp). This steel is used by various Western and Japanese manufacturers, including Kagemitsu and Echizen.
13C26.— similar to 12C27, but contains less chromium (Cr) and more carbon (C). It is analogous to Böhler-Uddeholm AEB-L steel (see below).
1.4116— the standard designation W-Nr for steel X50CrMoV15 (DIN designation). See steel X50CrMoV15.
154CM or ATS-34— 154CM (not to be confused with the higher quality CPM154 steel) is original American steel. ATS-34 from Hitachi is the Japanese version of this steel. Known as a high-quality stainless steel, it is not used in mass-produced kitchen knives because it is an expensive material. However, there are manufacturers who work with this type of steel in small batches for kitchen knives. It is hard to find and very costly (the price of kitchen knives starts at 300 euros). The steel has very high wear resistance but can be brittle at higher hardness levels. It is a good steel for kitchen knives, but there are better options available for a slightly higher price. The table below shows some differences between these types of steel.
| Steel. | C. | Si. | Mn. | P. | S. | Cr. | Mo. | Cu. | Co. |
|---|---|---|---|---|---|---|---|---|---|
| ATS-34 | 1.03. | 0.25. | 0.41. | 0.026. | 0.001. | 13.74. | 3.56. | —. | —. |
| ATS-55 | 1. | 0.35. | 0.5. | 0.03. | 0.002. | 14. | 0.6. | 20. | 40. |
| 440-C. | 1.04. | 0.74. | 0.36. | 0.003. | 0.003. | 16.92. | 0.46. | —. | —. |
| 154-CM | 1.05. | 0.3. | 0.5. | 0.03. | 0.03. | 14. | 4. | —. | —. |
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AEB-L.— Swedish stainless steel. A very pure fine-grained alloy. It is almost identical to 13C26 Sandvik Steel, with slightly less manganese (Mn) and 0.01% more sulfur (S). When this steel undergoes proper heat treatment, it achieves a very fine-grained structure, which is beneficial for wear resistance and edge retention. Devin Thomas uses it in his kitchen knives with very good results. For kitchen knives, this type of steel is hardened to a Rockwell hardness of 61-62.
AUS-8A— (57-59 HRC), also known as “molybdenum-vanadium” steel, similar to the steel used in the best German knives. It is excellent steel, with good rust resistance and an affordable price.
Cowry-X— Modern powder metallurgy steel, with particularly high carbon and chromium content. C — 3%, Cr — 20%. Cowry-X can be hardened to a very high hardness, and some manufacturers can achieve hardness levels of 65 or even 67 HRC. Consequently, it is also a very expensive steel. ZDP-189 and MC-66 are very similar to Cowry-X, as they have the same amounts of C and Cr. Unfortunately, I do not know the exact composition. Cowry-X has very good edge retention and exceptional strength. The steel is very difficult to sharpen compared to other types of steel, but it is not impossible. Hattori is currently the only manufacturer of Cowry-X kitchen knives. This series from Hattori starts at around 600 euros.
CPM™ 154— Modern Crucible’s powdered metallurgy version of steel 154CM. Significantly better than its predecessor. It is a much purer steel with finer carbides. The composition is identical to 154CM, but CPM154 apparently contains a small amount of vanadium, which makes it more wear-resistant. Strength and technological properties have significantly increased, making it easier for manufacturers to work with. Users may find it difficult to sharpen this steel, but it is very wear-resistant and can be honed to a very sharp edge. There are several manufacturers of “custom” knives that use it for kitchen knives. Factory knives made from CPM154 steel do not exist. Phil Wilson uses it to make fillet and chef’s knives. Hardness can reach 61 HRC, although this level of hardness is not often chosen.
CPM S90V™ (CPM420V)— CPM S90V (formerly known as 420V) is a highly alloyed steel produced by Crucible Particle Metallurgics (powdered steel). It offers very high wear resistance combined with excellent corrosion resistance. Due to its very high vanadium content, it can be challenging to work with. The upper hardness limit is 61 HRC. Only Phil Wilson has a kitchen knife made from this steel.
CPM™ S110V— CPM S110V is a highly alloyed steel produced by Crucible Particle Metallurgics (powdered steel). This steel also combines very high wear resistance with exceptional corrosion resistance. A unique feature is the addition of niobium (Nb). The recommended hardness by Crucible is 61-63 HRC. Since Crucible supplies this type of steel in very limited sizes, few knife manufacturers use it. Thanks to the addition of 3.5% niobium, the steel exhibits excellent wear resistance. (The Nb carbides are very hard, harder than vanadium carbides, and the overall carbide content in this steel is quite high).
CPM™ S30VIt was developed to offer a “balanced” stainless steel that could provide good edge retention, impact toughness, corrosion resistance, and sharpenability. It was created in collaboration with knife companies, knife manufacturers, and heat treatment specialists to achieve the properties they desired from knife steel. The lead metallurgist was Dick Barber, who used his experience in developing stainless steels at Crucible to build on proven designs, including important factors such as the amounts of chromium and vanadium used to achieve the right balance of properties. Molybdenum and nitrogen were added to balance corrosion resistance along with edge retention and impact toughness. A good response to heat treatment was achieved, allowing for processing in various furnaces. As a result, edge retention is better than that of steels like Elmax, S35VN, CPM-154, and BG42, although slightly worse than S90V and M390. Measured impact toughness was good, although it could potentially be improved with more optimized heat treatment. Corrosion resistance is “above average” and sufficient for many knives produced over the nearly 20 years of S30V’s existence.
CPM. S35VN.It was released in 2009 as a modification of S30V, featuring increased strength and workability. S35VN has good potential hardness, impact toughness, edge retention, and corrosion resistance. It doesn’t particularly stand out in any category, but it isn’t terrible in any of them either.
CPM S45VNdemonstrates improved impact toughness and corrosion resistance compared to S30V, while maintaining similar edge retention. It has slightly reduced impact toughness compared to S35VN, but with enhanced corrosion resistance and edge retention. S45VN is a good upgrade from S30V or S35VN. Alternatively, S35VN can be used for slightly higher impact toughness, but if impact toughness is a limiting factor, there are steels with significantly higher values. S45VN represents a kind of gradual step forward, but overall it seems to be an improvement over the earlier S30 series steels.
More details about some types of steel.
CROMOVA 18Yoshikin uses this stainless steel for its global brand. Cr stands for chromium in the alloy, Mo stands for molybdenum, and Va stands for vanadium. The chemical composition is unknown, except that the steel contains 18% chromium. It is a superior steel compared to X50CrMoV15 (commonly used in German knives) because it is a stronger steel. It has high rust resistance and is easy to sharpen due to its relatively low hardness of 58 HRC (which is low for Japanese steel).
Gingamifrom No. 1 to No. 5 (also known as GIN-1 or G1). Stainless steel, widely used as a substitute for VG-10 in kitchen knives. In fact, it is a variant of Hitachi VG-10. In kitchen knives, you will mostly find the GIN-3 variant, while in pocket knives, the GIN-2 or G2 variant is often used. This steel has slightly lower carbon content, a bit more chromium, and much less molybdenum than ATS-34. The steel does not contain nickel, tungsten, or vanadium. In short, it is an excellent stainless steel.
| Steel. | C. | Cr. | Mn. | Mo. | P. | Si. | S. |
|---|---|---|---|---|---|---|---|
| GIN-1. | 0.9. | 15.5. | 0.6. | 0.3. | 0.02. | 0.37. | 0.03. |
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MC66.— the equivalent of Henkel for Japanese steel Hitachi ZDP-189 PM. MC stands for Micro Carbide, and 66 refers to the (desired) hardness on the Rockwell scale. Henkel uses this in its Twin Cermax and Miyabi 7000MC lines, but it is produced in Japan (the Twin Cermax and Miyabi knives are also made in Japan. So there is little “German” in them).
R2.— identical to SG-2
SRS-15— Japanese powder metallurgy (PM) steel. An excellent choice for kitchen knives. It has a very high carbon content, and when combined with tungsten and vanadium, this steel achieves exceptional wear resistance. Overall, this steel can be easily hardened to a hardness of 64-65 HRC. Akifusa is one of the few manufacturers that produces knives from SRS-15 steel.
SG-2.— Japanese powdered metallurgy (PM) steel. Created by the steel company Takefu. It is also known as R2 steel. An excellent choice for kitchen knives. Fallkniven uses this steel under the name SGPS. SG2 stands for “Super Gold,” but that doesn’t mean there is gold in the steel. Kai Shun uses SG2 steel in their Elite line. It’s great steel, but according to the stated technical specifications, it is inferior to SRS-15 steel. Opinions on Fallkniven U2 knives vary; the steel may be less suitable for short pocket knives. Kai Shun Eline knives have received high praise. The steel can achieve high hardness. Shun Elite knives are officially hardened to 64 HRC, but there are also indications that they are hardened to 62 HRC.
SLD-Magic—Japanese steel from Hitachi Steel Ltd (Japan) (“Yasuki Hagane” YSS (Yasuki Specialty Steel)). This is an “upgrade” of the standard SLD (SKD11) steel, which is prone to chipping. This steel can be hardened to between 60 and 62 HRC. It is widely used by Tadafusa in their S series knives, with Tadafusa hardening this steel to a hardness of 62 HRC. This steel is already considered to be particularly good for kitchen knives, but due to its limited availability (and high price), you won’t often see it in kitchen knives.
SKD11.— Japanese tool steel. It is identical to AISI D2, DC11, and SLD. It is one of Hitachi’s special steels from the same family as SLD. It is resistant to rust, but not excessively so. This steel can be sharpened to a very fine edge, but it is sensitive to chipping (pieces can break off the edge during use), which may be related to too narrow a sharpening angle; generally, high-speed and tool steels should not be sharpened at too narrow an angle. The ideal angle is between 22 and 24 degrees. Yoshikane uses this steel for some of its kitchen knives, hardened to a hardness of 64 HRC. Some other manufacturers harden this steel to 62 HRC. Opinions about this steel are mostly positive.
C30B.— CPM S30V was specifically developed for kitchen knives by Crucible Metallurgy, and it’s something special. Aside from Shirogami and Aogami steels, there are no other steels specifically designed for kitchen knives. It is based on a very strong and wear-resistant steel, CPM3V. Chromium (Cr) is added to this mix. Due to the high amounts of added chromium and carbon, it is a very tough steel that is quite difficult to harden (maximum 62 HRC). As a result, it has better wear resistance than 154CM steel. The steel was very popular in the early 2000s when it first appeared, but proper heat treatment is not easy, and several manufacturers, even specialized knife makers, produce knives that are either too soft or chip too easily. This has negatively impacted the reputation of S30V. Compared to many other alloys, S30V is harder to work with. Therefore, many knife manufacturers prefer to harden the steel to a hardness of 58-60 HRC. Phil Wilson is one of the few knife makers using this steel.
VG-MAX.VG MAX is an optimized version of VG-10 steel with a higher content of chromium and vanadium.
VG-10.— Very good and highly rust-resistant steel. V Gold 10 steel is also known as VG-10 or sometimes V-Kin-10 (kin means “gold” in Japanese). This is a high-quality stainless steel produced exclusively in Japan. The “Gold” designation indicates high quality; there is no actual gold in the steel. The VG-10 alloy was originally developed by Takefu Special Steel Co., Ltd in Takefu, Fukui Prefecture, Japan. VG-10 was specifically designed for use in Japanese kitchen knives, but other manufacturers, such asSpyderco, AL-Marи.FällknivenThey also discovered this steel. The steel is used in well-known pocket knives, such asDelica, Endura, and Policeот.Spyderco, as well as inFällknivenA1 and K2 — White Whale. Most Japanese knives made of VG-10 steel are hardened to 60-62 HRC, Fällknivens.hardenedat 59HRC.
VG-10 steel is a unique alloy with a high carbon content, incorporating various concentrations of other metals such as chromium, vanadium, molybdenum, and cobalt. This steel was specifically designed for use in high-quality kitchen knives and is often referred to as “super steel” due to its exceptional hardness and long-lasting sharpness without becoming brittle. While there are many types of steel with extreme hardness (over 60 HRC), they often lack the desired impact toughness. Thanks to the addition of certain components, VG-10 steel is highly resistant to chipping without compromising its hardness and durability. VG-10 is similar to 154CM steel in terms of composition but retains its sharpness better and is more resistant to corrosion. This well-known steel has been around for several years and has fully proven its qualities. VG-10 requires minimal maintenance to prevent corrosion, is very sharp (sharper than Chromova18), and is easy to sharpen even at a hardness of 62 HRC.
X30CrMoNi1-5-1— also known as Cronidur 30. Stainless steel. Widely used in the aerospace industry. Henckel uses it in some of their “limited edition” knives. The nitrogen content in the alloy is quite high (0.40%), and overall, the blade gains improved properties due to the high carbon content, in addition to good wear resistance and relatively good impact toughness. The price tag (over €800) is very high for a knife made from this steel. Similar steels, such as Bohler-Uddeholm Vanax 35 and Vanax 75, have much higher nitrogen content (1.35% and 4.20%), and knives made from these steels are significantly cheaper. Additionally, vanadium is added to Vanax steel, which enhances wear resistance.
X45CrMoV15— German steel. It is similar to steel X50CrMoV15. The steel contains 0.45% carbon. It is not a special steel, relatively inexpensive, and is used by several Western manufacturers, including F. Dick.
X55CrMoV14— The steel used for Swiss Army knives, also known as Krupp 4110 or 1.4110, is part of the CrMoV steel family.
X50CrMoV15— German steel. It is very resistant to rust, but nothing special. X50CrMoV15 means 0.5% carbon, while the other part consists of 15% chromium, molybdenum, and sometimes vanadium (V). In this steel, X stands for carbon, which is a bit strange since carbon is usually known as C. The carbon content of 0.5% is low; however, knife manufacturers sometimes have different requirements for this steel. In fact, it has even less carbon compared to 440C steel! Nevertheless, it is much stronger and more resistant to corrosion. This steel has very low sharpness, so you will need to sharpen it very often to keep it sharp. It is a very poor choice for kitchen knives.
Nitro-BNitro-B stainless steel/1.4116N:
Nitro-B stainless steel (1.4116N) can be seen as an improved version of the X50CrMoV15 grade, which is already well-known for its qualities in knife making. Nitro-B is a variant of X50CrMoV15, containing a relatively high percentage of nitrogen. It was developed by the German holding company Buderus Edelstah, which is why this alloy is sometimes referred to as Buderus Nitro-B. The high nitrogen content in this case serves to replace carbon, which in iron alloys is responsible for strength and sharpness of the cutting edge. Blades made from this material undergo hardening with liquid nitrogen at temperatures as low as -80 degrees Celsius. In addition to other beneficial properties, this type of treatment provides the products with unparalleled hardness of up to 60 HRC on the Rockwell scale. The addition of nitrogen to its composition allows Nitro-B stainless steel to achieve even greater hardness while maintaining resistance to rust. This relatively new type of stainless steel for kitchen knives combines quality and versatility.
Nitro-V— this is stainless steel sold by New Jersey Steel Baron and first released in 2017. The steel was developed and produced in collaboration with Buderus Steel as a version of Uddeholm AEB-L, modified with nitrogen and vanadium.
Composition of Nitro-V steel
| Steel. | C. | Cr. | Si. | Mn. | N. | V. |
|---|---|---|---|---|---|---|
| Nitro-V | 0.68. | 13. | 0.4. | 0.65. | 0.11. | 0.08. |
| AEB-L. | 0.68. | 13. | 0.4. | 0.6. | ||
| 14C28N | 0.62. | 14. | 0.2. | 0.6. | 0.11. |
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Nitro-V is indeed very similar to AEB-L, having the same levels of C, Cr, and Si, with only a slight difference in Mn. The nitrogen content is the same as that of 14C28N, which may simply be related to limitations on nitrogen additions during standard steel production. The addition of vanadium is very small, likely too small to contribute to wear resistance and edge retention. Typically, such small vanadium additions are intended for grain refinement in low-alloy steels. In low-alloy steels, all the carbide dissolves at forging temperatures and high heat treatment temperatures, allowing for rapid grain growth. However, the high chromium content in stainless steels means that more vanadium is required for grain refinement.
4116 Krupp— German steel that undergoes cryogenic hardening during the hardening process. Variant X50CrMoV15. It is used in many entry-level knives from Henkels, Wusthof, and other German manufacturers, with a hardness of 54-56 RC. It has high stain resistance but mediocre edge retention. The composition includes 0.45-0.55% carbon, 0.1-0.2% vanadium, 14-15% chromium, and 0.5-0.8% molybdenum. In 2017, this steel began to be used in the production of mid-range knives of Chinese origin (between 7Cr17Mov and 440C San Mai), typically larger 9-12 inch chef’s knives and cleavers, hardened to RC 56-60 with improved edge retention. It is sometimes referred to as 1.4116. According to the DIN system, this steel is designated as X50CrMoV15. Other sources describe it as nearly identical to X50CrMoV15, with a chromium content that differs by about half a percent. Another name for this steel is 5Cr15MoV, thus it belongs to the CrMoV steel family, with this specific steel having characteristics similar to AUS-8, but possibly with slightly better corrosion resistance. (The alloy 5Cr14MoV is also essentially identical, with a slightly lower chromium content. In this naming format, the number to the left of Cr indicates the carbon content in tenths of a percent, while the number to the right of chromium indicates the percentage of chromium rounded to the nearest whole number.) Western-style fillet knives (i.e., flexible) made from 4116 steel are specifically marketed as intended for saltwater fish due to the corrosion resistance of this steel.
Friodur— this is stainless steel X50CrMoV15, primarily used by J.A.HenkelIn Zwilling kitchen knives, a distinctive feature of this type of steel is the heat treatment it undergoes. The steel is first heated to a high temperature and then cooled to -94 degrees Fahrenheit. This process makes the knife slightly harder and more resistant to rust.
X55CrMoV15— a type of steel 1.4116. Approximately the same, except for a slightly higher carbon content — 0.55%. Used by Messermeister.
ZDP-189— A very modern Japanese PM steel from Hitachi, with an extremely high content of carbon and chromium (C — 3%, Cr — 20%), but also includes molybdenum, vanadium, tungsten, manganese, and silicon. It has a very high hardness, with some manufacturers even hardening this steel to 65 or even 67 HRC. This is a very expensive alloy; Cowry-X and MC-66 are very similar to ZDP-189, mainly because these two have the same content of C and Cr. A representative from Henckel in Tokyo confirmed that MC66 steel is identical to ZDP-189. The exact composition is unknown. Unlike Cowry-X, ZDP-189 contains molybdenum, tungsten, and vanadium. In short, it has excellent edge retention and very high impact toughness. It is very difficult to sharpen compared to other steels and is relatively sensitive to “chipping” due to its extreme hardness.
6A/1K6Recently developed steel (56 ± 1 HRC). Blades made from this material are particularly resistant to corrosion due to the high chromium content. This is a very pure type of stainless steel. A higher carbon content provides better edge retention.
SUS420J2(56 ±1 HRC) — corrosion-resistant stainless steel with a high chromium content (14%) and a medium carbon content (0.3%).