Kolstål för knivar och rakblad - Sollex blogg
Johan Falk

Carbon steel for knives and razor blades

The number one ingredient to produce high quality blades and razor blades is high-quality material. Sollex manufactures knives, industrial razor blades and tools in the following materials: carbon steel, stainless steel, Bi-metal, high-speed steel, tool steel, ceramic materials, solid tungsten carbide and cemented carbide.

Extensive knowledge and experience of production, hardening and grinding results in industrial razor blades with sharpness and durability. Sollex blades have real sharpness and durability due to high-quality materials, proven and quality-assured hardening and precision grinding.

Blades in carbon steel

Carbon steel is a popular material for knives and razor blades because of its excellent hardness and edge retention properties. Carbon steel is an alloy of iron and carbon, with carbon content typically ranging from 0.5% to 1.5%. The higher the carbon content, the harder and more brittle the steel becomes. In addition to carbon, smaller amounts of silicon and manganese are usually added to the alloy.

Carbon steel is an excellent choice for knives and razor blades because it can be hardened to a high degree, allowing for a razor-sharp edge. Carbon steel knives and blades also tend to hold their edge longer than stainless steel counterparts. However, carbon steel is more prone to rust and corrosion, so it requires more care and maintenance.

There are several types of carbon steel that are commonly used for knives and razor blades. Some of the most popular include:

  1. 1095 Carbon Steel: This is a high-carbon steel that is known for its excellent edge retention and toughness. It is a popular choice for knives and razor blades.
  2. 1084 Carbon Steel: This is another high-carbon steel that is similar to 1095, but it has slightly less carbon content. It is also a popular choice for knives and razor blades.
  3. O1 Tool Steel: This is a low-alloy carbon steel that is known for its excellent edge retention and toughness. It is often used for high-end knives and razor blades.

Overall, carbon steel is an excellent choice for knives and razor blades if you are willing to put in the effort to maintain them properly. With proper care and maintenance, carbon steel knives and blades can provide excellent performance and durability.

Carbon content in carbon steel

Blades are made of different carbon steels due to different characteristics. The cutting characteristics is directly related to the carbon steel used. Many people talk about carbon content. In practice, this means a carbon content between 0.5 and 1%. The "eutectic" point for high carbon content is 0.76% and everything above is called high carbon. Carbon content higher than 2.1% causes carbon to crystallize to iron carbide or cast iron. Excessively high carbon content is thus unusable for making knives and razor blades.

Optimal carbon steel for industrial razor blades

Three-hole blade 2-013-X, 2-020-X, 2-030-X - Fully ceramic-coated razor blade for use in industrial plastic film production - SOLLEX.SESollex blades are, unless otherwise stated, made of carbon steel. We can manufacture blades and razor blades in a variety of carbon steels (or with a variety of DIN codes) but have a favorite steel with a very high carbon and chromium content. Adding chromium to the steel protects the steel from rust. The carbon steel used in Sollex blades is 95% made in Germany. Over the years, Germany has developed a particularly high level of competence and quality in the production of carbon steels with a high carbon and chromium content. Compared with cheaper steel German carbon steel performs better due to steel structure and the microstructure is more refined.

Hardening blades in carbon steel

Hardening carbon steel blades involves heating the steel to a critical temperature and then rapidly cooling it. This process, called quenching, transforms the steel's molecular structure, making it harder and more durable.

The first step in hardening a carbon steel blade is to heat it to a critical temperature. The critical temperature varies depending on the specific type of carbon steel used, but it is typically in the range of 1450°F to 1550°F (788°C to 843°C). At this temperature, the steel's crystal structure changes, allowing it to be hardened.

Once the steel has reached the critical temperature, it is quickly cooled by plunging it into a quenching solution, which can be oil, water, or a specialized quenching fluid. The rapid cooling causes the steel to become hard and brittle.

After quenching, the blade is typically tempered by reheating it to a lower temperature, usually between 350°F and 600°F (177°C to 316°C), for a specific amount of time. Tempering helps to reduce the blade's brittleness and increase its toughness and flexibility.

It is important to note that hardening and tempering a carbon steel blade requires skill and precision. Improperly quenching or tempering the blade can result in cracking, warping, or a blade that is too brittle or too soft. Therefore, it is recommended to leave this process to a professional or to have extensive knowledge and experience in metallurgy and blade making. When Sollex carbon steel blades are hardened, they have a constant and even hardness for optimal cutting work. Sollex blades made in such carbon steel can be extremely sharpened or given long durability.

Production process blades in carbon steel

We start with high quality carbon steel from Germany. Step one is that the carbon steel is rolled. Then we punch out the shape of the blade. During normal production, 600 punches are made per minute, which gives 1200 blades. Step three is to harden the steel which in German we call ”Eishardening” (German for our hardening process). The steel is then reheated to remove stress from the steel. The next step is marking and in some cases we do a surface treatment to protect our blades from rust. For industrial razor blades, this process is called oxidation. But in some cases we also choose to paint the blades to protect the carbon steel from rust. Now to Sollex's specialist competence: precision grinding. This is followed by us doing a second polishing to remove all possible burr from the grinding. At this stage the blade is finished.

Rust on carbon steel blades

How to prevent rust on industrial knives and blades - Sollex BlogCarbon steel rusts. So the blade needs to be lubricated. Well-oiled blades, on the other hand, can avoid rust for many years. But sooner or later, all steels rust. What you as a user can do to protect your blades from rust is to keep them well oiled and protect them from being exposed to oxygen. In addition, store the carbon steel blades in a dry place in a tightly closed package where the carbon steel blades are exposed to as little oxygen as possible. In Sollex stock we keep many blades well-oiled and in vacuum. 

Read more about how to prevent corrosion of industrial knives and blades in our other blog post.

Characteristics and advantages of carbon steel

Why is carbon steel used? An advantage of carbon steel is that it is easy to grind. Another advantage is that a blade in carbon steel can be sharpened sharper compared to stainless steel. The properties of the steel are evaluated in the form of hardness, toughness, wear resistance and edge sharpness. The blade should be hard enough to cut through the material. But not too hard as the blade toughness is lost. In such case the steel cracks or breaks. The resistance and edge sharpness gives the blade its cutting properties and durability.

Steel hardness is measured on a scale called Rockwell C or paraphrased HRC. The harder a steel is, the sharper it can be grinded. But a cutting edge in hard steel is more sensitive to deformation as the risk of chips being knocked out from the edge. A cutting edge in lower hardness can not be as sharp but on the other hand more durable. Knife and razor blade steels with HRC between 56 and 58 are called medium hard. HRC from 62 to 65 is called extremely hard. Sollex blades in carbon steel are in this definition extremely hard.





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