Steel is a very popular material. There is not, however, one single style. Countless variations with different chemical formulas exist. The result is that each has unique material properties, as well as weaknesses. Plenty of steel varieties are favorable for creating high-quality kitchen knives.
Good choices for stainless steel in a kitchen knife include the 400 series, which has a shiny finish, is cost-effective, and is very tough. The ATS-34 alloy is more expensive and has added molybdenum to raise its hardness.
Non-stainless steels that perform well in kitchen knives include the 10 series steels that can have very sharp edges at low prices. The 52100 variety is versatile, plus both hard and corrosion-resistant.
Although the names of those and other types of steel are certainly confusing, we will explain the naming conventions and compositions in detail. We will also cover the main kinds of steel found in kitchen knives.
What are the elements of steel?
Steel is not a material that occurs naturally in nature. It has been purposefully made for many generations for humanity’s benefit and has many uses. Steel is a metal alloy meaning it contains numerous chemical elements, though not all are metals themselves. Here is a breakdown of the elements that might exist within a piece of steel:
Iron (Fe)
Without iron, there could be no steel. Iron makes up the biggest component in all forms of steel. It is a magnetic metal element and is the most common metal on Earth. It exists everywhere, from the Earth’s core to the blood in our bodies. Iron by itself is soft and prone to rusting. Hence you will not find pure iron kitchen knives. Iron is combined with other materials to form steel, a much more appropriate choice for knives.
Carbon (C)
The second mandatory element in steel is carbon. This is what truly separates steel from plain iron. By weight, the amount of carbon in a steel alloy can be anywhere from under 0.1% to over 2%.
A content of less than 0.3% is considered low, while a number above 0.5% is called high-carbon steel. Over 1.5% carbon is very high content. The amount of carbon has a huge impact on the material properties of a steel alloy ― specifically, how hard it is.
Other elements
Chromium (Cr)
This is another natural earth metal. While many alloys contain chromium, steel only becomes “stainless” above a certain percentage of chromium. Stainless means the steel does not easily degrade due to rusting.
Definitions vary, but stainless steel must, in general, have over 10% free chromium atoms. This means that the chromium atoms do not combine with carbon to produce chromium carbide. Free chromium atoms create chromium oxide on the steel surface to protect against corrosion. The overall chromium percentage can be 18% or more.
Cobalt (Co)
By adding cobalt to steel, it can stay harder at higher temperatures. This is especially useful for tools that operate in hot environments because they remain effective in more extreme conditions.
Tungsten (W)
This element is most famous for its use in light bulbs. It is sometimes useful for steel manufacture thanks to its high strength and melting point. Tungsten makes steel more wear-resistant and strong at high temperatures. This property is important for drills because they generate lots of heat.
Molybdenum (Mo)
Molybdenum has the benefit of decreasing steel’s brittleness and like cobalt, it keeps steel strong at hotter temperatures.
Phosphorus (P)
This is an unwanted impurity because small quantities can make carbon steel even more brittle. However, it is occasionally added on purpose to improve the strength of some steel varieties.
Sulfur (S)
Sulfur is another impurity that appears during steel manufacture. Like phosphorus, it can make steel more brittle than intended. On the flip side, adding small amounts to a steel alloy makes it easier to work with and machine into shape.
The most common steel types in kitchen knives
You have probably noticed from the above list that “steel” is not such a simple term. If you are searching for a kitchen knife made from steel, you should be aware of the main types on sale. We will now take a closer look at the pros and cons of each steel variety.
Carbon steel
Composition
Obviously, carbon steel contains some amount of carbon, but how much? All steels contain some carbon, and if less than 0.3% of the weight is carbon, then it is mild or low-carbon steel. Medium carbon steel has 0.3-0.5% carbon as its weight, while any number above this indicates a high or very high carbon steel.
Carbon steel does not just have to contain iron and carbon ― it can include any of the other elements from the previous section (and more). However, quantities of those elements cannot be large enough to make it another kind of steel. For example, too much tungsten in the steel would make it tungsten steel and not carbon steel.
Properties
Adding carbon into steel affects the material by altering the lattice structure of the metal. More carbon causes more structural changes, the main benefit of which is increased hardness. Hard materials have high scores on the Rockwell scale, which means they resist scratching well. Knives made of carbon steel are also very strong so that they do not deform under large forces.
The downside of having a hard carbon steel blade is that it is quite brittle, and therefore, not very tough. A brittle knife is at risk of cracking or chipping from a sudden impact, i.e. hitting the ground. There is a trade-off between hardness and toughness. Increasing the carbon content of steel achieves a hard, scratch-resistant blade, but this sacrifices some toughness.
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Manufacture
Carbon steel knives are hand-forged which can raise the price of some models. Expert blacksmiths manufacture high-end Japanese kitchen knives by hand. Decades of knowledge and practice go into producing each knife.
Crafting knives by hand also has the advantage of differential hardening. This process allows different parts of the blade to have different heat treatments and therefore take on varying levels of hardness. You can have a hard cutting edge with a softer core. Such a design is a good compromise because the blade can better absorb energy while maintaining a wear-resistant surface.
Stainless steel
Composition
The decisive ingredient for stainless steel is, of course, chromium. Chromium content does not guarantee that steel is stainless until it exceeds 10% of the overall mass. Some manufacturers define stainless steel as having 10% of its mass as free chromium atoms.
Stainless steel alloys can contain other metals and varying amounts of carbon (some variants have a large portion of nickel). The key for steel to be stainless is that chromium should be the 2nd largest substance.
Properties
Stainless steel has a shiny, silvery appearance due to large amounts of chromium. The chromium oxide on the knife’s surface acts as a barrier to prevent moisture and air from penetrating the blade and causing surface or internal rust. This property is important for a knife since it is frequently in contact with water and salty or acidic foods that could corrode the blade.
Stainless steel is softer and weaker in comparison to carbon steel. On the other hand, stainless steel knives are less brittle.
Manufacture
This is rarely forged by hand. A lot of Western stainless steel knives are produced in large quantities in factories. The knife shapes are cut out of stainless steel sheets and then sharpened and fitted with handles. Each knife does not get nearly as much attention as a handmade high-carbon steel knife, hence they tend to be more affordable.
Powdered steel
Composition
Powdered steel contains a range of metals just like any other type of steel. It does not have any special components compared to other forms of steel. What makes this type of steel special are its manufacturing process and microscopic structure.
Properties
Compared to standard casting methods, the production of powdered steel yields a more uniform material with smaller grains and a very strong structure. With all the metal grains firmly bonded, this material achieves a good combination of both hardness and toughness. The edge of a powdered steel knife is easy to sharpen and stays sharp for a long time.
Manufacture
The technique of manufacturing powdered steel is at the forefront of metal technology. Instead of happening on an assembly line or in a blacksmith’s shop, this process currently takes place in laboratory environments. As such, the price of powdered steel knives is substantial.
Making powdered steel starts with atomizing molten steel with a liquid or gas spray. The liquid steel drips out of a large container and is immediately sprayed by a fluid. This solidifies the steel into tiny droplets. The solid droplets all collect at the bottom of a chamber and are ready for the next stage.
The tiny steel particles are then mixed and sintered (below their melting point) at high pressure to close any gaps. This forms a single ingot (a block of steel) in the shape of a knife.
Damascus steel
Composition
Damascus is of course the capital of modern-day Syria. The name originates from metal tools that used to be made in the city during the 4th century. Those tools were produced with a type of steel known as wootz that was imported from India.
Although tools made with original wootz steel exist, the exact process to create more wootz steel has been lost. Efforts to recreate the same recipe have so far been unsuccessful. Damascus steel itself consists of two or more types of metal (originally wootz steel) and sometimes iron.
Properties
Damascus steel is renowned for being very beautiful thanks to its wavy surface finish. Like the advanced powdered steel knives, Damascus steel knives are hard yet flexible and keep their sharp edges very well. This is a remarkable fact considering how much older this technology is than the manufacture of powdered steel.
Manufacture
Today, Damascus-style steel is made by hammering together many layers of steel and iron (sometimes over 50) at high temperatures in low oxygen. This is called forge welding.
Unfortunately, low-quality Damascus steel also exists, whereby a blacksmith only welds a few layers of metal. They will then treat the surface of the blade with acid to mimic the finish of a true Damascus blade.
What factors affect the performance of a steel knife?
Now we know what kinds of steel are used in kitchen knives, the next step is to understand what specifically makes a steel knife perform well. No knife can achieve perfection in every category, so a chef will have to make some compromises.
The advantage of steel is that numerous alloys exist so that knife makers can always try a new material to improve a knife’s properties.
Strength
This is a knife’s ability to resist permanent deformation due to applied forces. There are a few kinds of strength, namely, tensile, compressive, and torsional. In the case of knives, you want the blade to be strong enough to avoid bending or twisting while you cut with it.
You need to know the strength of the blade steel. If a knife is made from ductile steel, pushing it too hard could bend it significantly. This damage will need specialist repairs. Some knives are made from more brittle steel. Brittle knives can be strong, but once you exceed a certain force, the blade will snap completely rather than bend.
Toughness
Generally speaking, a tough material can absorb large amounts of energy without significant structural damage. That could mean a crack or dent in the blade. For a chef, this is relevant in case they drop the knife.
A tough knife will perform well as it frequently hits the cutting board while you chop. If a knife is swiftly cutting through meat and it strikes a hard bone, it could crack if it lacks toughness.
Hardness
Hard materials are difficult to scratch or engrave, so they score highly on the Rockwell scale. A hard knife blade will keep its finish for longer because most foods are too soft to scratch the surface. Hard blades are also some of the strongest. Yet, they are the most brittle too. Prioritizing hardness means that toughness is lost.
Softer knives can be scratched, though they can better absorb impacts. The most common method to harden steel is by adding carbon to the alloy. Carbon percentage in steel is proportional to the hardness and, unfortunately, the brittleness.
Rust resistance
All metal and steel knives are at risk of corrosion. This is a process every knife owner should try to avoid. The formation of rust not only spoils the beautiful silver finish of a steel knife but can also blunt the blade’s edge. Rust can potentially contaminate the food you prepare.
As we know, chromium is a substance that can give knives more stain resistance. Including this material in steel comes with a cost of decreased strength.
Blade geometry
A sharp knife is a useful knife. Some steel knives can be manufactured with particularly sharp edges. Companies can machine fine-grain steels (like powdered steel) more thinly than standard forms of steel.
You ideally want your steel knife to have a sharp edge that will stay sharp. Hard materials will naturally hold an edge for the longest, yet it takes more effort to sharpen them once they become blunt. This is another dilemma for knife owners.
The blade bevel and shape are other important factors, though they do not depend on the type of steel in a knife.
How is steel graded & classified?
Steel classification systems aim to group different steel alloys based on their constituents and material properties. This process is complicated by the fact that major Asian and European countries have established their own classifications, as well as America.
In America, the widely recognized grading system is called SAE. SAE assigns carbon and alloy steels a 4-digit code, while stainless steels have a 3-digit code. In the 4-digit code, the first number denotes the main alloy element and the last two describe the carbon content.
- 1XXX is some form of carbon steel (for example 1085)
- 4XXX is a molybdenum steel (e.g. 4030)
- 7XXX is a tungsten steel
- 304 is a common stainless steel
An alternative system is the Unified Numbering System (UNS). This covers all metal alloys, including steel. The format of these grades is a letter followed by a 5-digit code. The letter is symbolic and describes the main characteristic of the alloy. “T” stands for tool steels, “A” stands for aluminum alloys, and “E” indicates rare earth metals.
- G00001 – G99999 is the range of carbon and alloy steels (as per SAE)
- S00001 – S99999 is the range of stainless steels
- T00001 – T99999 is the classification for tool steels
The most common steels for kitchen knives
Stainless
Based on the SAE classification, the 400 series is a very common grade of stainless steel for kitchen knives. These kinds of steel have a higher proportion of chromium than the 300 series, but not so much as to weaken the blade.
The 420 grade of stainless steel is perhaps the best steel for cutlery and cheaper kitchen knives. 420 steel knives can be polished thoroughly and are highly rust-resistant, though, because of the low carbon content, they are quite soft and will blunt with frequent use.
440 steel is available in a few varieties (440A, 440B, and 440C). All have a higher amount of carbon than the 420, but 440C is the most desirable alloy. Despite its higher carbon content, it is still a type of stainless steel and so is not very brittle.
One other popular stainless steel knife grade is ATS-34. An ATS-34 knife has large portions of carbon and chromium and contains molybdenum to further raise the blade’s hardness. This is a premium steel alloy.
Non-stainless
Moving away from stainless steel knives, the 10 series includes 1060, 1084, and 1095 (based on SAE), and is a good choice of carbon steel for cutlery. Steels from this series are not too expensive, yet are tough and hard, plus they take on a sharp edge
W2 steel contains vanadium so is very hard and fairly tough. It is useful for creating outdoor and tactical knives.
52100 steel’s original use is in ball bearings. 52100 is a form of chromium steel that has both anti-rust and scratch-resistant properties. This alloy is effective in a range of both domestic and wilderness knives. Unfortunately, it is not the toughest option.
CPM 10V is another alloy consisting partly of vanadium. This material offers a practical combination of high wear resistance and toughness but is not cheap.
No kitchen knife steel is “the best”
The previous list only showed a handful of the steel alloys used for knife manufacture. You could spend time comparing the apparent strengths of each steel, but you will never find the best. Depending on whether you are a blacksmith, an amateur cook, an advanced chef, or an explorer, your personal preferences will vary.
If you hope to find a long-lasting, and sharp chef knife, your best option may be a high-carbon steel knife. You should be sure to visit our store since we offer expertly forged high-carbon knives at fantastic prices.
