Types of Steel
As you can imagine, there are many different types of steel available, and each can be used for a variety of purposes. When it comes to creating quality knives and axes, there are a few popular choices that are utilized by plenty of well-known knife/axe manufacturers on the market. This guide will help you understand the qualities, properties, and ideal uses of each kind of steel.
I’m going to explain the differences in various types of popular steel choices. Custom creations can use specialty steels if desired, but here we are only going to focus on the more widely used types.
Each steel type has its pros and cons, and the areas in which it performs best. It is important to remember that when utilized for its primary and intended reason, your knife should perform excellently. That being said, when a tool is abused or used improperly, it is unlikely you’ll see positive results regardless of the quality of the steel. Be sure you know exactly what you intend to use your knife or an axe for.
Stainless steel is often better for outdoor use because it withstands the elements and does not corrode easily, but carbon might be better if you are planning to be doing heavy work and need your edges to stay sharp longer. Also, steel does not work the same way with axes, hatchets, and larger tools as it does with knives. Certain desired properties in knives are considered undesirable or unnecessary in axes.
Carbon Steel (SAE 1050-1090, 5150, 5160, 52100)
Plain carbon steel is one of the most popular materials used in forging knives and axes. It is easy to sharpen and remain sharp. It is harder than other steels, like stainless for example, so it will maintain its edge better when exposed to hardened materials. Of course, all steel has a bit of carbon in it.
However, plain carbon steels contain a mixture of primarily carbon and steel, while other types of steel contain compounds of various other alloys and compositions. Carbon is the most important hardening element in all steel types and can help extend the life of your blade, although too much can reduce the toughness in the material, making it more susceptible to shock and damage.
Carbon can be classified into three sub-categories: low, medium, and high-level carbon. Medium and high are what you will most commonly find in many axes. Medium-level carbon has between 0.4 – 0.6% Carbon while high-level carbon has about 0.7 or 0.8% and above and used for knife blades. As per the naming system developed by the SAE (Society of Automotive Engineers), plain carbon steel is encompassed in the 10xx number series.
The last two numbers indicate the percentage of carbon included in the steel. Most axes use medium-carbon steel, most commonly around 1050 – 1060. This is because this steel is the best for honed edged weapons, and it is heat-tempered to diminish the risk of breakage and splintering.
Sometimes a high carbon 1070 or above is used. A high-quality steel that you can acquire is 1080 Carbon steel, or it’s Japanese counterpart, SK5. The metals in these materials are high quality, hardened with an RC level of up to 65. Blades of this material are a suitable choice for rugged, rough tasks, though they do demand a bit more care, as the presence of carbon makes the blade more susceptible to corrosion.
Another popular type of carbon steel is 5150 and 5160. The 50xx group of steel is classified as alloy steels in the SAE, and the last two digits determine the percentage of carbon, just like the above. At 0.5% and 0.6%, this is a medium-level carbon with enough chromium to significantly increase its overall performance, though not enough to consider it a stainless steel.
Due to its similarly low carbon content, this steel has increased toughness, hardenability, and shock resistance as compared to other materials. Easily one of the more durable and impact enduring of the steels, because of it’s outstanding toughness and hardness it is best suited for larger blades and makes for an excellent blade on a throwing axe or Siberian Batiya blade.
More on this steel is available here: https://www.azom.com/article.aspx?ArticleID=6704
The certified chemical composition of SAE52100 is:
The following table shows the chemical composition of SAE/AISI 52100 alloy steel.
|Iron, Fe||96.5 – 97.32|
|Chromium, Cr||1.30 – 1.60|
|Carbon, C||0.980 – 1.10|
|Manganese, Mn||0.250 – 0.450|
|Silicon, Si||0.150 – 0.300|
|Sulfur, S||≤ 0.0250|
|Phosphorous, P||≤ 0.0250|
The physical properties of AISI 52100 alloy steel are listed in the following table.
|Density||7.81 g/cm3||0.282 lb/in³|
The mechanical properties of AISI 52100 alloy steel are outlined in the following table.
|Bulk modulus (typical for steel)||140 GPa||20300 ksi|
|Shear modulus (typical for steel)||80 GPa||11600 ksi|
|Elastic modulus||190-210 GPa||27557-30458 ksi|
|Hardness, Knoop (converted from Rockwell C hardness)||875||875|
|Hardness, Rockwell C (quenched in oil from 150°C tempered)||62||62|
|Hardness, Rockwell C (quenched in water from 150°C tempered)||64||64|
|Hardness, Rockwell C (quenched in oil)||64||64|
|Hardness, Rockwell C (quenched in water)||66||66|
|Hardness, Vickers (converted from Rockwell C hardness)||848||848|
|Machinability (spheroidized annealed and cold drawn. Based on 100 machinability for AISI 1212 steel)||40||40|
Russian Yakut Knives steels.
U8 (GOST – U8) Carbon Steel. vs X12MF (Х12МФ Rus)
Many Russian Yakut knives saturating the market these days are made of poor grade quality carbon steel such as U-8 углеродистая сталь. The soviet industry used to make files out of this steel, and the old files are now available in abundance and used by craftsmen to make chip blades. If considering purchasing your knife from an unknown craftsmen confirm the type of steel used to forge your blade. Of cause there is no guaranty you will get an honest answer, but at least you do a due diligence.
With hardness of up to 64 HRC the Russian X12MF is a much better option than U8 in terms of corrosion resistance. Steel X12 MF is alloyed Tool steel, the composition of which determines its excellent technical characteristics. This brand has proved itself well both in the manufacture of household tools and stamped parts in machine building and other industries.
While compared to SAE52100 steels 66 HRC) or (O1 Steel 67 HRC) it performs better in terms of resistance to corrosion, but gives way in terms of maximum achievable hardness (X12MF 64 HRC max).
Further we will discuss the pros and cons of steel X12 MF for knives.
Characteristics of knives from steel Х12МФ
The trick to any steel is not in presence of alloy of iron with carbon, but their percentage ratio, as well as the presence of other components which will determine the properties of the finished product. This variety is produced by repeated welding, and alloys include vanadium, copper, silicon, manganese, molybdenum, phosphorus, nickel and sulfur. They determine the strength of all-metal knives made of steel X12MF and other products, resistance to corrosion, durability and cutting ability. The production of alloyed stamped steel is carried out in strict accordance with GOST and TU. Tempered at 950 ° C, which provides a hardness of up to 64 units of HRC.
Forging it is incredibly hard, and heat treatment,including setting the exact temperature, holding, tempering and other parameters, is incredibly complex. Nevertheless, there are master blacksmiths who make knives from this steel.
- The first requirement for knives is sharpness, but the easier it is to sharpen the tool, the faster it will get dull. X12MF is a hard steel to sharpen. The concentration of carbon in this alloy is 14.5-16.5%, which provides increased wear resistance, while also reduces the resistance to corrosion. This steel can not be called stainless, but also will not rust at the “sight” of water, like many Damascus steels. X12MF is still not maintenance free and needs to be properly taken care of.
The huge advantage of steel X12MF for knives is that even with hardness of 50 units it remains sharp event after extensive use.
- Molybdenum in its composition provides an alloyuniformity and homogeneity, which is very important for the cutting tool. Vanadium improves the hardness and strength of steel, increases its durability, and silicon provides a special strength. During numerous tests it was found that even after numerous bones cutting, opening of dozens of metal cans and hundreds of oak bar cuts, the blade of the knife remains sharp, without serifs and even able to cut the newspaper under its own weight.
- But all these advantages are opposed to one single drawback – fragility. Therefore, such knives should not be thrown, tested for bending, etc.
- Most often knives made from such an alloy have small blades. They are popular with hunters of Siberia and the Far North, because in such extreme climatic conditions it is simply vital to have a good knife with you. At competent processing and sharpening its quality surpasses quality of the cutting tool from other kinds of steel. Therefore, the demand for them in recent years, as well as the level of sales, has grown significantly.
Stainless Steel (400 series, 2Cr13, 3Cr13)
Stainless steel is another vastly popular and commonly used material as it is easy to maintain and withstands corrosion effectively. The major ingredient in this material is chromium and at least 12% of it must be present to be considered stainless steel. At this level, the chromium oxidizes, giving the steel its underlying properties, which include improved resistance to wear and tear but on the other hand reducing its hardness.
Nevertheless, in order to be hardenable, as stainless steel is known to be a particularly soft metal, it can contain limited chromium, lowering its resistance to corrosion. Stainless steel is found in a vast array of products and tools available in various markets, such as cutlery, surgical tools, jewelry, and more. It is generally inexpensive, cheap steel, but it is regularly combined with quality materials like nickel to increase its effectiveness.
The most popular type of this steel found amongst knives axes and hatchets is 420 Stainless Steel. Harder than 410 but softer than 440 (as the number order would suggest), this material only has about 0.3% – 0.4% carbon, meaning that is a fairly soft steel, and has moderate edge retention.
Conversely, it is incredibly corrosion resistant, and stands up well to the elements, making it ideal for tools that are exposed to water for long time (in Marine applications) or minor chemicals often. It has above average ductility when hardened, and can reach up to RC53. 2Cr13 and 3Cr13 stainless steel are the Chinese equivalent of 420 Stainless Steel.
They reach up to RC50 and RC52, respectively. This is a steel that is ideal for mildly to moderately sized workloads that require prolonged exposure to water, snow, chemicals, dirt, and the like. They are easy to polish and maintain and sharpening is a short, manageable task.
Another commonly used type of 400 series stainless steel that is used when making commercial axe heads is 420HC, which is High Carbon 420 Stainless Steel, and should not be confused with the aforementioned 420. Because of its higher level of carbon, it has increased hardness and edge retention, giving it a considerable boost in strength compared to its counterpart.
This version of the steel unites the edge holding, wear resistance of the high carbon steels with the corrosion battling properties of chromium alloys. It is considered quality steel, as it combines a complimenting combination of desirable characteristics, ideal for tools that you expect to be used often.
Stainless Steel (AUS 6, 8, 10)
AUS-6, AUS-8, and AUS-10, also known as 6A, 8A, and 10A in that order, are stainless steels produced by Japanese steel maker Aichi Steel Corporation. Their carbon content can be compared to steels such as 440A, 440B, and 440C, respectively. 6A has an average of 0.65% carbon content, and usually competes against steels like 420 stainless steel when it comes to weapon making. 8A holds a carbon content of about 0.75% and is considered moderately tough middle-level steel. 10A has a carbon content of around 1.10%. It is often compared to 440C though their biggest difference is the slight decrease of chromium in 10A.
Blades forged with AUS steel are usually hardened to RC 55 – 58 on the Rockwell Scale. This stainless steel is designed and to have a sharp, biting edge. However, with its ability to hold a sharper, finer edge comes the need to sharpen more often, so it’s a bit of a trade off. Sharpening will result in an easily and accurately achieved razor-sharp edge, but you will find yourself maintaining the blade frequently.
The biggest difference and a major benefit in the AUS series is the addition of vanadium. The addition of this alloy gives the already corrosion resistant stainless steel enhanced erosion protection and increased toughness. In addition, it makes maintaining the blade a breeze. Cleaning, sharpening, and polish are effortless thanks to the advanced characteristics of the metal. Overall, these blades tend to be great quality, rust-resistant, tough, and durable and are generally available inexpensively.