Overview of Knife Blade Steels

Choosing the best knife for yourself and your task at hand can feel overwhelming when looking at all of the options that there are. You have to decide between steel types, blade shapes, and what the knife’s purpose is. To make this process easier for everyone, I have decided to do a beginner’s series. To start off with, I am going to define the different terms used in ranking knife steels and then go into the different popular types of steels and dig deep into their details to help you figure out which knife is your perfect option. 

Basic Terms

For starters, there are a few different terms that I should define. First off, the Rockwell Hardness Scale, this is a scale that determines the hardness of a material by a series of tests. The lower the number of Rockwell Hardness, the softer the steel. The higher the number, the harder the steel. Often times, these numbers are paired with either “HRC” or “RC”. These terms just say that the number is on the Rockwell Hardness scale, just two different ways of saying that. With steel, the hardness is often described as the strength of the steel.

Another important aspect is toughness. Often times, hardness and toughness are used as synonyms, however there is a difference.  The toughness of a knife is referring to how much force the blade can endure before chipping, cracking, or breaking during heavy use. The thing about toughness and hardness is that the harder a knife is, the less tough it will be and vice versa.

The third main factor in steel is corrosion resistance. Corrosion resistance is how well the knife holds up to rust and other discolorations of the steel.

While hardness, toughness, and corrosion resistance are the three main factors in steel, there is another factor in choosing which steel to purchase. The edge retention of a knife’s steel. This is used when describing how long the blade will stay sharp after a period of usage.

Before we dive in, let’s go over the most common elements present in steel and the properties they give it.

  • Iron is the main ingredient in steel.
  • Carbon is one of the most important factors, as it functions as a hardening element and makes the iron stronger. Every type of steel will have some amount of carbon, and oftentimes the amount can be telling of the quality of a blade. Low carbon means there is 0.3 percent or less carbon in the alloy, medium carbon is typically between 0.4-0.7 percent, and high is generally considered 0.8 percent and above.
  • Chromium is what makes stainless steel stainless. Technically all steel can rust, but types with more chromium (usually around 12-13 percent) are much less prone to it.
  • Cobalt adds strength to the blade.
  • Manganese hardens the blade, but also makes it brittle if added in high quantities.
  • Nickel adds toughness to the blade.
  • Molybdenum helps a steel maintain strength at high temperatures.
  • Tungsten increases wear resistance.
  • Vanadium increases wear resistance and makes the blade harder.

Different Types of Steel

Now that we all understand the basic terms used to describe the steels, let’s focus on the individual types of steel that can make up a knife blade.

AUS 8

Another popular steel used in knives is AUS 8 steel. This steel is also referred to as 8A steel.  The Rockwell Hardness level is 57-58. One of the biggest pros about AUS 8 steel is how well it can hold an edge. It is also extremely easy to sharpen. This type of steel has .75% carbon, so this means that it is a relatively hard knife. This is a cheaper knife and for the price, it has great corrosion resistance capacities. Overall, this type of steel has a good balance of toughness, strength, edge holding, and resistance to corrosion, especially for the price. Because of its lower price, it won’t hold up forever, but is great if you are looking for a cheaper option.

VG-10

VG-10 steel was originally used for kitchen cutlery, because it is one of the highest levels of stainless steels. This is also because this steel holds a great edge and has a fantastic anti-rust property. The carbon content in this steel is around 1%. This steel is one of the hardest steels and because of this, it can get brittle and chip. VG-10 steel contains vanadium which is what gives it the extra toughness. Because of the high quality of its stainless properties and its strength, VG-10 is sometimes known as a super steel. This steel is very similar to ATS-34 and 154CM steel. The Rockwell Hardness is 60. VG-10 steel originated in Japan and was first introduced in America by Spyderco. While the cost might seem steep when first looking at it, you get what you pay for and it is well worth the extra money.

Damascus

While Damascus steel is a popular steel, it is very different than any of the other steels that we’ve been discussing. This steel is made out of two or more layers of different types of steel and “folding” them together. Folding, is just a specific type of welding, where the different layers of steel are fused together. After these layers are fused together, the steel is etched with acid. Because the acid reacts differently to the two different types of steel, it reveals a striped pattern out. Knives with Damascus steel has a high toughness, but the process is long and the cost of production is high. This means that Damascus blades are usually just used for the aesthetic in decorative blades. Damascus is actually considered a precious metal. These knives are usually collector’s knives. The Rockwell Hardness level of Damascus steel is a little bit trickier because there are different types of steels in it, but they usually range from a 53 to 62.

VG-1

VG-1 is also known as V Gold 1 steel and is a high Carbon (C) Molybdenum (Mo) stainless steel manufactured by Takefu Special Steel Co.,Ltd.[1] It is not the same steel as VG-10.

VG-1 has a Carbon (C) content between 0.95-1.05 %, Chromium (Cr) content between 13.0-15.0 %, Molybdenum (Mo) content between 0.2-0.4 % and contains less than 0.25 % of Nickel (Ni).[2] During forging, Mo and Cr form hard double carbide bonds, which help improve the abrasion and corrosion resistance of the steel.[3] It is usually heat treated to reach hardness of 58-61[4]

Claims are made that VG-1 has better sharpness, edge retention, point strength, shock and strength characteristics than 440C, VG-10, or ATS 34 stainless steels, though any of those alloys may be better than VG-1 in individual categories.

VG-1 is also used in hairdresser’s scissors, kitchen knives and blades for food-processing machines.

440A, 440B and 440C Stainless Steels

Grade 440C stainless steel is a high carbon martensitic stainless steel. … Grade 440C is capable of attaining, after heat treatment, the highest strength, hardness and wear resistance of all the stainless alloys.

Cromova
Cromova is the name Global use for their stainless steel. It is steel with 0.8 % carbon and added chrome, molybdenum and vanadium. Cromova steel has a fine grain structure and can be sharpened very sharp. It combines good cutting characteristics with good rust resistance.

Hyper Molybdenum Vanadium

This is a stain resistant steel blades that is bacteria resistant. This steel gives the blade incredible strength, toughness, and corrosion resistance. Korin Masamoto are the main manufacturer using this steel for kitchen knives. HRc: 58-59.

154 CM Steel: This is high quality steel — arguably one of the best available for knives. It has a carbon content of 1.05 percent, it holds an edge well, and has  pretty good toughness for how hard the steel It is tougher than 440C and is often compared to ATS 34 because the two are so similar.

M390 Steel: M390 as 1.9 percent carbon, is very stain-resistant, and has excellent wear resistance. It has vanadium as an additive, and consequently is a popular hard steel. This is also the type of steel used most often for surgical applications.

N680 Steel: Last but not least, N680 has .54 percent carbon. This is another very hard steel that is highly stain resistant, making it good for saltwater applications.

Carbon Steel

General features of carbon steel make it perfect for Japanese blacksmiths as this steel is often used for Traditional Japanese knives. The only downside is that it’s not rustproof so a higher maintenance skills are needed.

The Japanese company Hitachi Metals makes special cutting steels which represent the highest global standard and are used for almost all the knives we offer. These Yasugi Special Steels , named after their place of origin, are produced from iron sand, the same material that was used to make the legendary Samurai swords. They have a highly pure structure and thus offer the best achievable sharpness for cutting.

Blue Paper Steel (Aogami)
High carbon steel is specifically developed for tools and knives. This one has highest wear resistance and lowest toughness. Very good steel and a very popular choice for high end Japanese kitchen knives. A lot of Japanese custom makers use it. Easy to sharpen, even high hardness. Edge holding is just outstanding. Original Japanese knives made from these materials are treated with non-corrosive, food-safe oils (e.g. camellia oil) to prevent oxidation.

White Paper Steel (Shirogami)
Identical to Blue Paper Steel (Aogami) , except for the absence of Cr and W. It’s very pure carbon steel. Very popular knife steel for high end Japanese cutlery and especially with Honyaki type blades.

Very good edge holding, very high working hardness. This means you can grind it to exceptional sharpness, which retains it for a long time. These blades are particularly suitable for the gentle preparation of foods – but they are prone to oxidation, which means your knife will rust if not taken care of.

Yellow Paper Steel (Kigami)
Better steel compared to SK series, but worse than both, Aogami and Shirogami. Used in high end tools and low/mid class kitchen knives.

SK Steel series
Solid performer as a cutlery steel. Low grade steel, mainly due to impurities. Used mainly in hand tools like axes, hammers and cheap kitchen knives.

Japanese Steel (Nihonko, Hagane, Virgin Carbon Steel)
Important steel that has been used to produce knives in Japan since ancient times, providing better sharpness than common stainless steel. The Japanese steel is a premium grade of steel that boasts extremely high carbon content. It is manufactured in limited quantities in Japan. The steel is harder than German steel and has a greater sharpening potential. It also maintains an edge longer than other lower-carbon steel formulae. These features make Japanese steel the ideal material for manufacturing high performance cutlery.

Ceramic

Although very sharp and durable, they are brittle and do not stand sideways pressure. NOT suitable.