What’s the best material for your knife blades? Are you still wondering whether you should get an alloy or stainless?
Knives are not as simple as they look. While their blades seem to look the same, they are actually made of different materials. Yes, knives use different types of steels and choosing the best one may depend on various factors.
If you are into steel for knives, then you are just on the right page. We will be discussing this in detail in the next sections.
Common Elements of Steel
Steel is not on the periodic table because it’s a man-made substance created from a combination of elements mostly iron and carbon. Steel is an alloy made up of iron with a few tenths of a percent of carbon making it stronger and more fracture resistant than regular iron.
More elements may be added for better properties. For instance, stainless steels that are corrosion- and oxidation-resistant usually need 11% chromium.
Due to its high tensile strength and being low cost, steels have become very popular in buildings, infrastructure, tools, ships, trains, cars machines, electrical appliances and weapons like knives!
Aside from the two, there are many other elements added to the mix to give the steel other properties.
Here are the common elements in steel.
Iron– The main ingredient in steel.
Carbon – One of the most critical elements present because it makes iron stronger. Every type of steel will have some amount of carbon present.
Chromium – Makes stainless steel stainless. Technically all steel can rust but those with more chromium around 12% to 13% are much less prone to it.
Cobalt – Adds strength to the blade.
Manganese– Hardens the blade but it can also make it brittle if added in high quantities.
Nickel– Makes the blade tougher.
Molybdenum– Helps steel maintain strength at high temperatures.
Tungsten– Increases wear resistance.
Vanadium– Increases wear resistance and makes the blade harder.
Main Types of Steel
Steel is a powerful element and it is used in most things you come into contact with every day. Steel comes in several grades and holds unique chemical compositions.
According to the World Steel Association, over 1.8. million tons of steel was produced worldwide in 2020 with over 3,500 different grades. Although there are countless types of steel, most fall into one of four categories.
1. Carbon steel
Carbon steel makes up most of the steel production worldwide by about 90%. Most knives are made of carbon steel because of their high durability.
There are three levels of carbon steel — low (.30%), medium (between .30% and .60%) and high (between .60% and 1.5%). Considered to be strong, but carbon steel needs to be clean as it’s prone to corrosion.
2. Alloy Steel
Alloy steel is a mixture of several different metals including nickel, copper and aluminum. They tend to be cheaper and more resistant to corrosion.
Alloys are the preferred material for some car parts, pipelines, ship hulls and mechanical projects.
3. Stainless Steel
Stainless steel is probably the most popular and it is used around a lot, which makes it hard to know if one is actually referring to real stainless steel. Real stainless steel is shinier than the others due to high levels of chromium, which makes it highly resistant to corrosion.
Stainless steel knives are typically a combination of high carbon and chromium between 11% to 17%. Also, since it is flexible, easy to manipulate and of very good quality, it can be found in surgical equipment, home applications, silverware and exterior cladding for commercial and industrial buildings.
4. Tool Steel
Tool steel is famous for being hard and both heat and scrape resistant because it contains durable elements like tungsten, molybdenum, cobalt, and vanadium.
5. Other steel types
There are also powdered steels and Damascus steel. Crucible Industry’s CPM stands for Crucible Particle Metallurgy also known as powdered steel is produced using fine powder of carbide particles and allows for a very uniform distribution of carbide. With finer-grained powder steels, your knife can take a sharper edge.
Damascus steel is a pattern-welded steel that is a result of combining two steels together. The performance of the steel is dependent on the steels being utilized and the vivid patterns that come from the acid etching process.
Carbon Steel vs Stainless Steel
Carbon steel and stainless steel are the most popular types of steel. Each of them has offers an advantage not present from the other.
Basic steel is simply iron and carbon. Eventually, steel makers learned to add more elements like a pinch of cobalt or a dash of chromium.
The addition of more elements like vanadium or molybdenum changes the steel’s character.
Here’s a tip, the higher the carbon content, the harder the blade and the better edge retention. However, it should not be overdone because too much carbon can also make the blade brittle and reduce its toughness.
So, should you get a carbon steel blade or a stainless steel blade? All steels contain carbon. However, the defining difference between the two is that stainless steel blades typically contain between 10.5 percent and 16 percent chromium in the alloy.
Carbon steel often includes various additional elements to give steel specific properties but it doesn’t include chromium or it’s too low. Carbon steel is popular for its ease of sharpening, edge retention ability and flexibility.
Meanwhile, there is no such thing as stainless steel. An alloy is absolutely impervious to rust and it would have to contain so much chromium, so it would be rust-resistant and would not be as useless as a knife. The addition of chromium to a steel alloy and when the metal is heat treated, its protective chromium oxide turns back crud making stainless blades easier to care for.
Below are the carbon steels and stainless steels available in the market.
• 1095 Steel
• 0-1 Steel
• D-2 Steel
• 52100 Steel
• 5160 Steel
• AUS-6 and AUS-8 Steel
• 8Cr13MoV Steel
• Sandvik 12C27 Steel
• 154 CM Steel
• ATS-34 Steel
• VG10 Steel
• CPM S30V Steel
• CPM S35VN
• ZDP-189 Steel
• Elmax Steel
• M390 Steel
• H-1 Steel
How is Steel Graded and Classified
Steel grading is often used by engineers, scientists, architects and even government agencies to boost their confidence in the consistency and quality of materials. However, grading steel is not easy because steel is made worldwide and every country has its own classification system.
For instance, the ASTM Grading System assigns each metal with a letter prefix based on its category. For example, the letter “A” is for steel and iron materials. It will then assign a sequential number that reflects that metal’s specific properties.
Meanwhile, the SAE Grading System utilizes a four-digit number for classification. The first two indicate the steel type along with the alloying element concentration and the last two reflect the carbon concentration of that specific metal.
Factors that Determine Steel Quality
Now that you are already aware of the various elements that make up steel, it’s time to look into the characteristics that make one a quality knife steel.
Here’s a checklist of the things to consider when looking at the steel’s quality.
1. Initial Sharpness
Knives are popular for their sharpness, after all, that’s what they are used for. Whether it’s a kitchen knife or hunting knife, we want a sharp edge or sharp knife blades so they could cut through our ingredients or any material quickly and effectively. Its initial sharpness is the sharpness of the blade “out of the box.”
This goes hand in hand with blade geometry (which you will find below). Certain angles make a knife sharp.
For instance, a 30-degree inclusive edge means that each side of the blade is sharpened 15 degrees. A more acute sharpening angle gives better cutting performance compared to knives with more obtuse angles.
However, the more obtuse the angle, the more stable and durable the knife. There are certain blade steels that are more stable at highly acute angles.
Edge retention represents how long the blade will retain its sharpness when subject to periods of use. It is a combination of wear resistance and an edge that resists deformation. It’s the ability of the steel blade to hold an edge without frequent resharpening.
Hardness is often interchanged with toughness with many thinking they are just the same thing. However, hardness and toughness are not necessarily the same, but they are dependent on one another.
Hardness is the ability of steel to resist deformation when subjected to stress and applied forces. It is directly correlated to strength. You can use Rockwell Hardness Scale to familiarize the hardness in steel.
High carbon steel content combined with elements like manganese will make the steel very hard but brittle. This is the reason some knives are rigid but brittle and they tend to chip and break easily.
Toughness is the blade’s resistance to chipping, cracking, or breaking from impacts and torsion pressure. Steel is tough when it survives sudden load.
Elements that rank mid-range on the Mohs Scale of Mineral Hardness like nickel will add toughness to the steel. Sporting and combat knives with shorter, thicker blades typically have high ratings in the hardness and toughness departments.
5. Water Resistance
This refers to the blade’s ability to keep its edge through rigorous use in multiple applications. Hardness and wear resistance go hand in hand because steel with high levels of carbides are more wear-resistant and high carbon steel is some of the hardest. But then again, a knife that is too hard can easily chip or break. So, it has to have elements within the steel to make it tough.
6. Corrosion Resistance
Any steel can rust under the right conditions. But some steels with high levels of corrosion-resistant elements like chromium makes it that much harder for them to rust.
However, steel strength and wear resistance are often sacrificed for anti-corrosive properties.
7. Ease of sharpening
One of the most frequently overlooked aspects of blade steel is its sharpenability. No matter how sharp your knife is, it will eventually become dull after years or usage or maybe sooner depending on the materials
If your knife gets dull easily, it is very important that it is easy to sharpen. Sharpening should be an easy and pain-free process, not an all-day affair just to bring them back to sharp.
However, an easy to sharpen knife generally does not exhibit excellent edge retention. Those with better edge retention don’t need to be sharpened frequently.
8. Heat Treat
Heat Treatment is the process of hardening and tempering the blade steel using heat. The process increases the strength of the edge tremendously. When done correctly and consistently, a heat treat goes a long way towards the performance of a knife.
High hardness increases the edge retention but at the cost of brittleness. Meanwhile, the low hardness increases toughness at the cost of the edge strength. Also, the effects of heat treat vary based on the composition of the steel.
Blade geometry affects the performance of the knife. When the thickness behind the edge decreases, its cutting and slicing performance improves.
Knives like Spyderco Chaparral have a very thin edge at only 0.14″. Meanwhile, knives from Ka-Bar Becker BK2 tend to have thicker blades which makes them tougher but less slicey compared to thin knives.
10. Cutting task
Yes, it is given that knives are used for cutting, but it depends on what material you cut. Knife steels with extreme hardness and edge retention work well at cutting through warehouses full of cardboard but when it hits a staple, the knife may suffer a chip.
Tough steels excel at camp chores and batoning wood but don’t work at very thin edge profiles while maintaining edge stability. There is no perfect blade, no perfect knife. So when buying or making a knife, make sure it’s perfect for its job.
Best Knife Steels
At this point, you already have enough ideas about steel for knives. So, I’ll be sharing with you the various steels that are within your options. To give you an overview of their prices and quality, I will categorize them in various ranges.
• 400 Series
• Sandvik Series
If there is a particular application you have in mind, then you should use the steel popularly used for that. For example, for outdoor or tool knives, the blade should be tough, hard and wear-resistant. A2 Steel, D2 Steel and M2 Steel are highly recommended.
For kitchen knives, high carbon steel, stainless steel or a combination of both is most preferred. The popular steels are 400 series, AUS series, ATS series, and SXXV series
There are so many varieties of steel available for pocket knives and kitchen knives, so choosing the best knife can be confusing and a bit challenging. If you are among the knife makers or buyers and still weighing on what steel to choose, hopefully, the article above is helpful to you.
Knife steels vary depending on the materials or elements used. There are also several factors that will help you identify quality knife steels but you can’t find one that has it all. For instance, a thick knife is tough but it is not the best for cutting and slicing. Meanwhile, thin blades are best for cutting and slicing, but they are not tough.
So, when choosing the best knife steels consider the edge retention, sharpness, toughness, and more based on the application or how you will use your knife. Make up your mind on whether you want to have one with excellent corrosion resistance, decent edge retention or slightly better edge retention. Familiarizing the types of steel to use will surely help you easily sharpen and hone kitchen knives for superior edge.