Best Knife Steel
Ready to slice and dice your way into action? The best knives can cut through the toughest of materials like a hot knife through butter. It can provide you with the best defensive action. However, what makes a knife the best knife?
Well, the performance of your knife will drastically depend on the materials it's made from. And more specifically the steel used to create the blade. Think about it, a knife is nothing without its blade, so buy a knife with the best knife steel possible.
Easier said than done right, you might have noticed there are a ton of different blade options available. Some blades are super tough and difficult to sharpen, but will stay sharp for a long time. While others are softer and much easier to sharpen, but will dull much quicker.
So how do you know which to buy? We'll dive into some different blade types and hopefully clear up some of your confusion. It doesn't have to be a difficult decision, a few basics can help you make a quick decision on the best knife steel for your new pocket knife.
Why Does Blade Steel Matter
So, why exactly should you look at the blade steel when buying a knife? Well, to summarize it in a sentence: ‘Blade steel can make or break your knife.’ Here are a few reasons why blade steel is important.
1. Quality of Knife
The blade steel is one of the most dominant factors when it comes to determining the quality of the knife. Of course, there are other factors to consider as well, but blade steel is perhaps the most important one.
Let’s face it, no one will care if the knife is ergonomic or looks cool if it can’t cut. The blade steel determines whether the knife will have good edge retention or whether it will be tougher than other knives. Plus, the composition of the blade steel can actually determine whether the knife will be resistant to rust and corrosion as well. It can affect the edge geometry as well as the blade profile.
For example, a high carbon content steel will hold an edge for longer while one with a low content will result in a springy knife.
All in all, the blade steel can impact the quality of the life as well as how long it will last in your hands. However, beware! Most manufacturers come out every year with the most extravagant sounding names for blade steels. When in fact, the steel might not even be better than others.
Most of these manufacturers make use of the fact that users are unaware of blade steels and thus try to sell them their clever marketing ploys. So, we suggest that you look into these knives and blade steels yourself!
2. Purpose of Use
Another important reason to investigate blade steels is the purpose of use. You might be using the blade for some specific purpose such as hunting, camping or just for defense. In case you need one for camping or the outdoors, you might need a blade steel that sharpens easily. Since you will use the knife a lot, you need to ensure that it the steel is quite tough as well. In this case, knives with high carbon can help you.
On the other hand, if you are using knives for defense or combat purposes, then Steel with high Manganese and Carbon should be used. This tough steel makes for an excellent choice for heavy-duty tactical knives.
So, the blade steel can determine how well you can perform with the knife for certain uses!
Blade Steel Properties
As we already mentioned, the blade steel can heavily affect the quality of the knife and where you can use it. It depends on how well the blade steel can hold its edge and how easy it is to manufacture. To determine the quality and the different types of steels, we categorize the blades according to the following properties.
The hardness of a blade steel determines how easily it can resist any physical deformation. You can measure the hardness on a special scale called the Rockwell Scale. In fact, out of all the properties, hardness in the only one that can be measured with a number. Most manufacturers measure the Rockwell hardness by using a machine that exerts a lot of pressure on the steel until it dents.
They, then, measure the indent and determine the appropriate rating for the steel. The harder the steel, the tougher it will be to dent, and it will be able to resist pressure more. However, some steels can be treated so that they are tougher and more resistant to pressure and remain on the lower scale of Rockwell hardness.
Next, hardenability is a factor that manufacturers consider and not the buyers. It can determine how well the steel will harden when it goes through artificial treatments. Manufacturers prefer a steel which they can harden to an extent they like. Too much hardness can make the blade harder to sharpen. So, most companies want to set their own range of hardness to meet their own purposes.
Ductility is the ability of the blade steel to flex and bend when under pressure. This property can determine the major difference between brittle blades and flexible blades. If the blades are less ductile then they can easily fracture or shatter. On the other hand, if they are more ductile, they will just bend under pressure and will easily come back to their original position.
However, most folks mistake ductility with toughness. These are both independent properties. For example, a filet knife is flexible without the toughness.
We know it can get confusing to differentiate between hardness, toughness, durability, and ductility. Toughness is how much pressure the steel can handle before it fractures. In more basic terms, it determines how much time it takes for the steel to shatter, when under stress. If it takes a long time for the steel to shatter, this means, it is very tough.
It has nothing to do with hardness. In fact, the harder steels are more prone to fracturing easily while softer steels are much tougher. Plus, it can help you determine if your blade will chip well.
5. Edge Retention
One of the most important properties of blade steel must be the edge retention. The edge retention is how well the steel can hold an edge without the need to sharpen too often.
Softer steels are quite easy to sharpen; however, they cannot hold an edge for too long. On the other hand, harder steels have great edge retention but are harder to sharpen.
6. Resistance to Corrosion
Another important property of steel is how well it can resist corrosion. This is an important property to look for if you live in a more humid area or use it underwater. Also, the property is quite important to consider in survival knives. Since you might face different weathers, it is important your blade is corrosion resistant.
Of course, all blades will rust after some time. No blade can be absolutely rust-proof. Even stainless steel is resistant to corrosion at best. However, blades such as H1 steel or the X15TN might be considered somewhat rust proof.
However, it is also important to note that high corrosion resistance comes at the price of the edge performance.
This is yet another property that is important for manufacturers and not buyers. It defines how easily it can be ground, treated and machined. Manufacturers prefer steels that they can easily treat.
REMEMBER: You cannot find a blade steel that ranks high in all the properties. Even if you shell out a million dollars, you can never find a blade that is perfect in all aspects. These properties are traded off for others most of the time!
For example, steels that have high hardness may be less resistant to wear. Furthermore, harder blades tend to be more brittle, so they might not be as tough. On the other hand, a blade that has better edge retention will be quite hard to sharpen.
Furthermore, if a blade has a higher resistance to corrosion, it is bound to have poor edge retention. So, the main point is that you must find the perfect balance between these properties. Find properties that suit your purpose better.
Common Elements in Blade Steel
You might already be aware that steel is an alloy which means it was formed by fusing two different elements. Of course, the basic composition of the steel is an alloy of iron and carbon. Other elements are often added to it and the content may be varied to give birth to a steel with different properties. However, the basic composition will always be the same.
Steel is quite popular due to the fact that its composition can be varied to a large extent to end up with blades with different properties. Following are the elements most commonly found in steel.
Iron makes up the base of the steel. Most steels contain at least 85-90% of iron in it.
Carbon is also a base element to steel. All steels contain at least some amount of Carbon in them. However, high content carbon steels usually have about 3-4% carbon in them.
Chromium is found in stainless steel where the steel has about 10.5% chromium and an average of about 14%. Plus, t is used for martensitic stainless steels. Moreover, the corrosion resistance is highly dependent on the amount of the Chromium dissolved into the steel matrix.
Cobalt is a shiny and hard metal that allows you to work with metals as well as heat treat them.
Copper is a reddish-brown metal that is used in wiring and electrical cables. However, it is also used in steel.
Manganese is a hard-transitional metal that is used in steels to increase the hardness. It has no significant contribution though since it makes the steel brittle as well.
Molybdenum can improve the hardenability and is actually an alloy that is attractive to manufacturers. It tends to be quite brittle and reduces the overall durability of the steel.
Nickel is a silver-white metal that can help in increasing the toughness as well. It also helps improve hardenability. In fact, it is mainly used in Austenitic stainless steel.
Niobium is a silver metal that adds ductility as well as strength.
Nitrogen is used along with carbon to increase the hardness. However, it does not decrease the corrosion resistance like Carbon. It is not used more commonly because of difficulties in manufacturability.
Phosphorous mainly increases strength but compromises on it with reduced ductility and toughness.
Sulfur is a non-metal element such as phosphorous that can lower the toughness of the blade.
Tungsten is a metal that helps increase the toughness as well as hardness.
Vanadium is yet another common element found in most steels. It forms very strong carbides which are not dissolved during any heat treatment processes.
Knife Steel Treatments
Heat Treatment process basically helps blade steel garner special properties. This is mostly done by subsequently heating and cooling the metal. What this does is it changes the physical properties of the steel. It can help turn soft metal alloy mixtures into a hard, deep cutting blade.
However, the temperatures at which the physical properties are changed depends on the different types of metals involved in the steel. Since each metal has a different structure, it will respond differently to specific temperatures. Even if the metals are present in the smallest quantity, they will still dictate the heat and temperature that you can use in the heat treatment.
These physical changes can include changes in:
The cooling process can also affect the structural changes. An example would be high carbon steels. If these are cooled rapidly, they will be much harder, while if cooled slowly, they will result in softer steels.
Steps in Heat Treatment Process
In this step, the steel is heated to high temperatures of about 1500 deg F for a time of about 30-35 minutes. Then the steel is further heated to temperatures of about 1900 deg F for 60 minutes.
In this step, the steel is heated to high temperatures of about 1500 deg F for a time of about 30-35 minutes. Then the steel is further heated to temperatures of about 1900 deg F for 60 minutes.
The next step can either involve cooling down steel to room temperature or to super low/cryogenic temperatures. This helps by hardening the carbon in the steel.
Next, the steel is heated to a lower temperature this time! However, the temperature mainly depends on the composition of the steel. For low carbon stainless steels, the temperatures can reach up to 950 deg F while for high carbon steels, the temperature can be a mere 400 deg F.
The steel is heated at these temperatures for about 60 minutes or less. Industries often repeat the process if more strength must be imparted.
Types of Heat Treatments
There are various types of heat treatments depending on the type of properties you wish to impart. Toughness and Hardness are the most common properties for which steel is treated. The following types of heat treatments include.
Normalizing steel helps make it more uniform in terms of the grain size as well as the composition. Manufacturers can use it to produce martensite as well bainite. The process basically results in a less ductile steel that is strong and hard.
It acts like a hard reset and equally distributes the carbides. Otherwise, the carbides would bunch up and the blade would not have good edge retention. Normalizing happens by heating steel to 1500 deg F and then soaking it in water for 5 minutes before cooling it in the air.
Annealing means that you heat the metal and then cool it at slower rates to renew the structure of the alloy. It allows softening the metal which makes it easier to grind and machine.
Annealing is usually done by heating it above the critical temperature of steel and then cooling it very slowly, about 50 deg F for an hour. This is also very useful in repairing any damages caused by cold working.
Hardening is a process that, obviously, makes knives harder. The process involves heating the knife to high temperatures of 1900-2000 deg F and then cooling it. This way the knife becomes harder but also very brittle.
4. Cryogenic Treatment
This involves soaking or quenching the steel into very low temperatures of about -90 deg F and even -290 deg F. You can usually see the benefits of this treatment with super stainless steels.
Popular Knife Blade Steels
With everything we have covered your should be able to recognize some of the properties in these steels and identify how they impact performance on a blade.
American powder-made stainless steel developed by custom bladesmith Chris Reeves and Crucible Materials Corporation. CPM S30V is best known for its wear and corrosion resistance and is considered to be one the best blade steels ever made.
It's chemistry promotes the formation and even distribution of vanadium carbides which are harder and more effective at cutting than chromium carbides. Vanadium carbides give the steel a very refined grain structure which further contributes to the sharpness and toughness of the edge.
An American made, but less expensive version of CPM S30V. D2 is an outstanding high carbon, semi stainless steel tool steel that is used for steel cutting dies in nearly every tool and die shop in the US.
It's a popular choice because it can be hardened far beyond the favored 60-61 HRC. Consequently, this air hardening steel takes an excellent edge and holds it exceptionally well.
Although the first bladesmith to use this steel was Jimmy Lile, the strongest convert has been Bob Dozier who has made this steel popular by mastering the heat treating process.
The original 154-CM is a proprietary, American-made, high-carbon, high-alloy, space-age, stainless steel that was first used for knives in the early 1970's.
At that time it was a vacuum-melted steel, but after a few years the quality declined because the manufacturer ceased to vacuum-melt the steel. Eventually, bladesmiths moved away from 154-CM to the Japanese equivalent steel ATS-34.
However, today, CPM 154-CM is made by short-run blade steel manufacturer Crucible Industries and the quality has been restored.
American-made stainless steel that, until the discovery of 154 CM in the early 1970’s, was the single most popular, high-carbon, stainless steel among custom bladesmiths.
First used by Gil Hibben around 1966, 440C is a great steel when properly heat-treated. Its Molybdenum content allows it to take a fine edge, while its high carbon content lets it to do a good job of holding it.
Yet, its Manganese content also causes it to do an exceptionally good job of withstanding impact for a stainless steel and, its relatively high Chromium content causes it to be highly resistant to corrosion. It does a good job for not only hunting knives, but is also favored for large, heavy duty knives.
0.95 - 1.20% Carbon
16 - 18% Chromium
420HC is a somewhat less expensive American-made stainless alternative to 440C. While it is similar in composition to 440C, it neither withstands impact as well nor, does it take and hold as fine an edge and, it is not as corrosion resistant.
0.4 - 0.50% Carbon
12 - 14% Chromium
420J2 is an inexpensive American-made stainless steel typically reserved for very inexpensive production knives. It's an adequate blade steel when you need a knife, but it does not take a very fine edge nor does it hold it well. It also isn't nearly as resistant to corrosion as 440C.
12 - 14% Chromium
VG-10 is a proprietary Japanese stainless steel that was developed specifically for use in high end Japanese chef’s knives. Consequently, VG-10 stands for V Gold 10 ("gold" meaning high quality), or sometimes V-Kin-10 (kin means "gold" in Japanese) because this steel is of such high quality. It's considered to be the gold standard Japanese blade steel.
Due to its composition, which results in a very fine grain structure, it's able to take a very fine edge and, its high degree of abrasion resistance enable it to do an excellent job of holding it.
But, it is generally a more expensive steel, so sometimes it is laminated to a tougher stainless steel such as VG-1. so that the VG-10 forms the core of the laminate (called San Mai construction).
A high-carbon, high-alloy, Japanese copy of CPM 154-CM except for a 0.1% difference in Manganese content, ATS-34 is vacuum-melted steel that is widely considered to be the second best blade steel available after CPM-S30V.
AUS-10 is a tough, highly corrosion resistant, stainless steel that is commonly used in knives that will see hard use.
AUS-8, similar to AUS-10 is a tough, highly corrosion resistant, stainless steel that is commonly used in knives that will see hard use.
VG-1 is a less expensive Japanese stainless steel somewhat similar to 420HC but which is mostly used by Cold Steel on knives that require a tough blade steel composition. It has a Carbon content between 0.95-1.05%, a Chromium content between 13.0-15.0%, a Molybdenum content between 0.20-0.40% and, it contains less than 0.25% Nickel. Plus, it has a typical hardness of 58-61 HRC
8Cr13MoV is a Chinese equivalent to AUS8 and thus, it is a relatively tough stainless steel that holds an edge relatively well. Many budget pocket knives use this steel, some great examples would be the Spyderco Tenacious and the Kershaw Cryo. It contains 0.80% Carbon, 13% Chromium, 0.40% Manganese, 0.20% Nickel, 0.5% Molybdenum, and 0.10% Vanadium and, it has a typical hardness of 58-59 HRC.
Sandvik 12C27 is a Swedish stainless steel and is Sandvik's most well-rounded knife steel. It provides excellent edge performance allowing razor sharpness, high hardness, exceptional toughness and good corrosion resistance. It contains 0.60% Carbon, 13.5% Chromium and, 0.40% Manganese, and, it has a typical hardness of 57-59 HRC.
Bohler M390 Microclean
This is a high end, third generation, Austrian-made, powder metallurgy, stainless steel with a very small grain size that is equivalent to a super version of CPM S30V.
In fact, it was developed specifically for knife blades requiring good corrosion resistance and a very high degree of hardness for excellent wear resistance.
Uddeholm Elmax Superclean
A third generation Austrian, powder-metal stainless steel that is noted for its fine carbide distribution with extremely low inclusion content. Its an excellent balance between corrosion resistance and edge retention.
It contains 1.70% Carbon, 18% Chromium, 1.0% Molybdenum, 3% Vanadium, and 0.30% Manganese and, it has a typical hardness of 57-59 HRC and 60-62 HRC with deep freeze. For maximum toughness, it should be hardened to 57-59 HRC and, for maximum wear resistance, it should be hardened to 60-62 HRC.
Is a conventionally made Austrian stainless steel that is Bohler’s best value in a corrosion resistant blade steel with excellent edge holding capabilities. In fact, it will take as fine an edge as VG-10 and it will hold an edge as well as both ATS-34 or VG-10.
It contains 1.08% Carbon, 17.3% Chromium, 1.1% Molybdenum, 0.1% Vanadium, 1.50% Cobalt, 0.4% Manganese and, 0.40% Silicone and has a typical hardness of 58-60 HRC for maximum toughness and, 60-62 HRC with cryogenic treatment for maximum wear resistance.
An Austrian-made, conventionally produced, 440C stainless steel equivalent with a high degree of hardness and wear resistance. It has good corrosion resistance in the hardened and tempered condition. It contains 1.05% Carbon, 17% Chromium, 0.50% Molybdenum, 0.40% Manganese, and 0.40% Silicone and has a typical hardness of 57-60 HRC.
An inexpensive, fine-grained, German, stainless steel that is made by Thyssen Krupp, and is commonly referred to as “Solingen Steel”. Also, it is a medium carbon stainless steel commonly used for low-end factory knives where the blades are fine blanked because, if the carbon content were higher, the blade blanking dies would wear too fast.
However, the balance of carbon and chromium does give it a high degree of corrosion resistance and also impressive physical characteristics of strength and wear resistance.
Non-Stainless blade steels
Now let's take a quick look at some of the non-stainless blade steels often used. These steels with offer highest wear and impact resistance. They are often used wear chopping and hard use blades are required, such as axes and machetes.
An American-made, non-stainless, steel designed to provide maximum resistance to breakage and chipping in a highly wear-resistant metal.
It has an impact resistance greater than that of A-2, D-2, Cru-Wear or CPM-M4 and other shock resistance metals while providing excellent wear resistance and a high degree of hardness.
It contains 0.80% Carbon, 7.50% Chromium, 1.30% Molybdenum, and 2.75% Vanadium and, it has a typical hardness of 58-60 HRC.
An American-made, non-stainless, electric-furnace melted, oil-hardened, non-shrinking, general-purpose, tool steel that is popular with custom knife makers.
It's a highly versatile steel since it can be used for stock removal as well as forged knives and is often utilized for tomahawks and axes as well. With a proper heat treatment, O-1 will take and hold a very fine edge while remaining remarkably tough and durable.
O-1 is an ideal steel for edged weapons and tools because it is known for its ability to be differentially heat treated. It contains 0.95 percent Carbon, 0.6 percent Chromium, 0.6 percent Tungsten, 0.1 percent Vanadium, and. 1.1 percent Manganese and it has typical hardness of 53-54 HRC.
An SAE grade plain carbon steel commonly used for tools. The carbon content and lean alloy make it a shallow hardening steel depending on carbon content and, this combination of factors makes this one of the toughest steels available.
When quenched, it produces a near saturated lathe Martensite with no excess carbides; avoiding the brittleness associated with higher carbon materials. This steel is particularly well suited to applications where strength and impact resistance are valued above all other considerations and will produce blades of nearly legendary toughness. It contains 0.90% 1.03% Carbon and 0.30% - 0.50% Manganese and, it has a typical hardness of 56-58 HRC.
SK-5 is the Japanese equivalent of American 1080 and is a high carbon steel that combines a mixture of carbon rich Martensite with some small undissolved carbides. The excess carbides increase abrasion resistance and allow the steel to achieve an ideal balance of very good blade toughness with superior edge holding ability.
Due to these characteristics, this grade of steel has been traditionally used for making hand tools and has stood the test of time and use over many years in many countries. Last, it contains 0.80%-0.90% Carbon, 0.15% - 0.50% Manganese, 0.15% - 0.35% Silicone.
All in all, you can never get a knife that has all the properties. If it ranks higher in one area, chances are high that it will rank lower in the others. However, the main criteria for choosing the best knife should be the purpose of use.
If you plan to use it more frequently, then you might want a knife that is easier to sharpen. If you are going to be using it in water, then corrosion resistance should be the biggest factor here! So, it’s up to you to decide which ones hold a competitive ‘edge’ for you!
Resources & Further Reading
If you wish to dive deeper into the best blade steels, below are some of the best resources on the internet for this topic. I especially like A.G. Russell's charts and refer to them often.