Knife Steel – Hold an Edge Verses No Rust – Have Both!
Knife steel is a critical component of the custom knife. Making a good homemade knife is a job of patience and dedication to precision craftsmanship. A custom knife maker must understand the science of metallurgy when choosing a suitable knife steel.
To rust or not to rust, that is the question. In fact, that’s just one of the questions. Keeping a big lead or not keeping a big lead is another important matter! Many custom knife makers are finding a middle ground for those two questions.
High carbon steels and stainless steels are acceptable if properly alloyed. High carbon steels are typically forged steels. They can be differentially tempered. This property gives the knife maker more options. You can better control the hardness of the edge and still have a sturdy knife with an elastic back.
Let’s first consider some of the most common carbon knife steels available.
10xx series
1095 is the most popular knife steel. It is a simple steel consisting of 95% carbon and 4% manganese. Other 10 series steels are used to make knives, such as 1084, 1070, 1060 and 1050, etc. Each of these steels is decreasing in carbon content and therefore also decreasing in wear resistance. At the same time, as the carbon content decreases, the toughness increases. As such, some of the lower carbon designations are more commonly used for swords.
O-1
O-1 steel is another high carbon steel that gives razor sharp edges but dulls faster than A2 steel. O-1, like A2, has a carbon content of 1%. It has 1.35% manganese, 0.5% chromium, 0.35% silicon, and 5% tungsten. O-1 steel is more forgiving of those who fail to get a decent head start. In short, it’s easier / faster to hone to a sharp edge than some of the other options, but it doesn’t stand up to abuse either. 0-1 is very popular with smiths and blacksmiths. It’s tough, though not as tough as the 5160.
L-6
L-6 is very similar to O-1. It’s basically bandsaw steel. Possibly the best steel for a knife if maintenance is not an issue. It rusts very easily, but holds the edges very well. It is also very hard. It is a favorite of counterfeiters.
W-2
W-2 is reasonably strong and has a good edge due to its 25% vanadium. It is also 25% manganese and silicon. It is not that common or popular.
A2
A2 steel is almost a stainless steel. Al (5%) does not have enough chromium. It has 1% carbon, 0.6% manganese, 1% molybdenum, and 2% vanadium. It is not prone to rust. A2 steel is popular for combat knives due to its toughness. The edge toughness of A2 steel is improved by cryogenic treating the blades to -320 degrees Fahrenheit. A2 steel is much harder than 0-1 carbon steel, and although it is more difficult to sharpen, it stays sharp longer. Works best between 30 and 35 degrees. The problem with A2 steel is that it tends to fracture more easily when the bevel is ground to less than 30 degrees. A2 is stronger than D2 and M2, but has less wear resistance.
M2
M2 Steel is a fine grain moly / tungsten high speed tool steel. It has 85% carbon, 0.25% manganese, 4.2% chromium, 0.30% silicon, 5% molybdenum, 6.35% tungsten, and 1.9% vanadium. It is an excellent choice for high temperature applications. For example, the annealing temperature of M2 steel is approximately 1000 ° F. It is slightly harder and more resistant to wear than D2, however M2 rusts more easily.
D2
The “D” series steels are classified as cold work tool steels. D2 steel is a premium quality tool steel. With a carbon content of 1.5%, it is better at holding edges than less exotic stainless steels. D2 has a fairly high chromium content (11.5%) and is sometimes referred to as “semi-stainless”. It is a highly respected, air-hardened, high-carbon, high-chromium tool steel. It has 1% molybdenum and 9% vanadium. It has extremely high wear resistance properties. D2 steel is one of the strongest knife blades you can get and is a favorite of the best custom knife makers. Anyone who has ever used a good D2 steel blade in the field is raving about the steel’s cutting ability, durability, and edge holding properties. Simply put, D2 steel can produce one of the best blades available for a work knife.
5160
5160 steel is a common spring steel. It’s basically 1060 with 1% chromium added to deep harden it. It is used in swords, axes or other high impact tools. 5160 steel is popular now for a variety of knife styles, but is generally used for larger blades that need more toughness. It’s quick and easy to sharpen, and when lateral force resistance comes into play, the 5160 is a champ.
50100-B
50100-B is the AISI designation for the same steel as 0170-6. The B indicates that vanadium has been added. This steel is a good chromium-vanadium alloy that has similar properties to 0-1, but is much less expensive. It is essentially 52100 with 1/3 less chromium.
52100
52100 is often compared to 5160. It has a bit more carbon content than 5160 and therefore has a better edge. However, it is not that difficult. The trade-off is in wear resistance. Many hunting knives are now made from this steel.
Now let’s consider stainless steel blade alloys.
Stainless steel is designated as such if it has more than 13% chromium. However, the ASM Metals Manual says it should only be greater than 10%. There are also different numbers. However, this difference is likely due to the amount of free chromium available. There are many stainless steel alloys with different corrosion resistance properties that make it a good material for knife blades.
420 and 420HC
420 is an extremely soft steel because it has less than 5% carbon content. It does not hold the edges well, but it is very resistant to stains and is often used for less expensive knives. It is also often used to make diving knives. 420 HC is designed to be more like 440A by including more carbon.
440A, 440B and 440C
This series of steels increases its carbon content from A -.75%, to B -.9%, to C – 1.2%. 440C steel, if properly hardened, is an excellent blade steel. It is very strong and has good edge holding qualities. It does not have as good an edge as the ATS-34, but it is more resistant to stains. This complete series is very resistant to oxidation. The 440A is the most resistant to rust and the 440C the least.
AUS-6, AUS-8 and AUS-10
This is a Japanese series of steels that roughly compares to the previous 440 series. The carbon content increases from AUS-6 -.65%, to AUS-8 -.75%, to AUS-10 – 1.1%. AUS-6 would be more closely compared to the cheaper low-end 420. AUS-8 is a mid-level steel like GIN-1 or ATS-55. AUS-10 competes with higher end steels and generally compares well to 440C. It has slightly less chrome than 440C, but all three steels in this series have vanadium added. Vanadium improves wear resistance and grain, which gives these steels the ability to sharpen to a very fine edge. Vanadium also improves wear resistance. These steels are often referred to as 6A, 8A, and 10A.
GIN-1
GIN-1, also known as G-2 is generally compared to AUS-8 and ATS-55. It has less carbon and much less moly than ATS-34. It has a little more chrome and is generally used for less expensive knives.
ATS-34
ATS-34 steel is universally recognized for its clamping and edge-taking capabilities. It is a Japanese steel that compares favorably with the American version, 154CM, which is not that popular. ATS-34 is definitely stronger than 440 steel, so the tip of this steel is less likely to break, but it is not as resistant to rust. ATS-34 is usually hot or cold rolled depending on its thickness, but both are likely annealed (heat treated).
ATS-55
ATS-55 is one notch behind ATS-34, because it is moly free. Without the moly, it also does not hold the edges, is not as resistant to rust, and has less resistance to wear. Compares favorably with GIN-1 and AUS-8
BG-42
BG-42 is becoming more popular. It is also more expensive than the ATS-34, which can limit its popularity. Due to the addition of vanadium and twice as much manganese as ATS-34, it will hold a significantly better edge and also have better toughness than ATS-34. It is a bit more difficult to work.
S30V, S60V and S90V
This series of steels is packed with a higher number of alloys due to the particle metallurgy process which is very different from conventional steel making methods. These are high vanadium knives and compare favorably to BG-42. They are probably more resistant to wear and tear than any other stainless steel. However, they are even more expensive than the BG-42 and even more difficult to work with. This primarily relegates them to the realm of experienced custom knife makers. S60V is often referred to as CPM T440V and S90V as CPM T420V.
Whether you’re looking for an easy-care knife or a knife that has a great edge, learning about the options available can give you the best of both worlds.