Types of steels in knives
Types of steels in knives
When choosing a pocket knife, you need to pay attention to the type of steel from which the blade is made. Steel is the essence of the blade and is primarily responsible for how the knife functions. Steel is an alloy (i.e., a mixture) of carbon and iron that is enriched, often, by other elements, to improve certain properties depending on the use required of the knife.
In the knife industry, different types of steel are created by diversifying the types of additional elements, as well as the way the blade is rolled and heated (i.e., the finishing process). See our knife steel composition table to read more details on these elements.
Finally, the different types of steel used to make knife blades present varying levels of these five key features:
Hardness is the ability to withstand shape distortions in situations of stress and force. Knife steel hardness is often referred to as strength and is usually measured using the Rockwell C ("HRC") index.
Toughness is the ability to withstand damage such as cracks and crevices when metal is used in harsh working conditions. Stiffness also defines the ability of the metal to flex without breaking. Cracks are the biggest enemies of the knife, and it is never easy to repair them. Note that the stronger or harder the steel, the less rigid it will be. Also, hardness measurement has much less understandable standards than hardness measurement.
Abrasion resistance is the ability of steel to bear damage due to adhesive and abrasive. Abrasion occurs when soft surfaces meet hard surfaces. Adhesion erosion occurs when debris is displaced from one surface and adheres to another. Abrasion resistance usually corresponds to the hardness of the steel, but it is also greatly affected by the specific chemical compound of the steel. In steels that exhibit an equal level of hardness, the steel that has the greatest number of carbides (think microscopic, hard, abrasion-resistant particles) will generally withstand abrasion better.
Corrosion resistance is the ability to resist corrosion such as rust caused by external elements such as moisture, humidity, and salt. Note that high corrosion resistance does not require the proximity of the entire tip performance.
Preservation of the tip
The tip retention represents the period in which the blade maintains its sharpness during the period of use. Everyone is talking about tip retention these days, but unfortunately, there is no set of standards for measuring tip retention, and much of the data is subjective. For me, tip retention is a combination of abrasion resistance and a warp-resistant tip.
Unfortunately, to get to the "best knife steel" one must, very simply, maximize each of the features we mentioned above ... This is a compromise. The greatest compromise is the balance of strength or hardness with stiffness. Some of the blades can be made to be particularly hard, but they will crack if you drop them on a hard surface. Alternatively, a blade can be particularly stiff and flexible, but will have difficulty maintaining its sharpness. Also, note that the term "stainless steel" is, often, confusing, as all types of steel will change color to one degree or another if exposed to the forces of nature for a long enough time. If you know how you plan to use the knife, you can, in general, determine what is the best steel for you.
Knife steels are popular today
These are the most common steels from which knife blades are made today. Do not get carried away with the approximate ratings, this is not an exact science, and this is simply my way of categorizing the types of steel into general performance categories based on a variety of factors.
Common types of steel
The most common types of steel are usually included in the following categories:
Tool steel - These are mainly hard steel alloys, which are used to make cutting tools. Some of the popular steels in this group are D2, O1, Crucible CPM series knives (for example, CPM 3V), and other high-speed steels such as M4 or A2.
Carbon steel - in general, produced for rough use, for which the hardness and durability are important. This steel is commonly used in the manufacture of survival knives and machetes. They have a sharp edge and relatively, it is easy to sharpen them again. The compromise is that they are more prone to corrosion, due to the low amount of chromium in them. The most common carbon steel for knife use is 1095, but 1075 (Condor Condor) as well as steels such as 1060 are also widely used.
Stainless steel - basically carbon steel, to which chromium is added so that it can withstand corrosion and other elements that increase performance levels, usually at the expense of hardness. This is by far the most popular category today, and it includes the 400, 145CM, AUS, VG, CTS, MoV, Sandvik and Crucible SxxV series of steels. Note that in order it to form stainless steel, the steel must contain at least 13% chromium.
What is the matter with CPM steels?
CPM stands for "Crucible Particle Metallurgy" - Crucible's particle metallurgy, which is a process for producing high quality tool steels. The American company Crucible Industries is the only manufacturer of CPM steels, formed by casting the molten metal through a small nozzle, in which high-pressure gas splits the liquid stream into a spray of tiny droplets. The drops are cooled, solidified into a powder, and then undergo a process of hot isostatic pressing (HIP), in which the powder coalesces and is compressed. The trick is that the HIP process ensures that each of the fine particles will have a uniform compound, without separation in the alloy. The result of the process is steel with better rigidity and abrasion resistance, which can be ground, and heat treated for maximum impact.
What about Damascus steel?
Damascus steel originates from the Middle East, from countries such as India and Pakistan where it was first used before BC. It can be easily identified because it is characterized by a swirling pattern caused by combining two types of steel and is therefore often referred to as "welded" steel (it should not be confused with Wootz steel, which is similar only in its exterior). There are many myths regarding the strength and capabilities of Damascus steel, but today it is popular mainly due to its aesthetic beauty. It is mostly sold to collectors.
Remember, blade steel is not everything. Knife buyers should be careful not to dwell on research into the perfect type of steel, as on its own, it does not dictate how the knife will function. Steel analysis has become scientific, to some extent, so it is easy to get lost in the maze of statistics. Note that just because a blade is made of premium steels or of the highest range I mentioned above, it will not necessarily be better than inferior steels. The heat treatment techniques used by the manufacturer, as well as the design of the blade, play a significant role in the result of the knife performance!
In practice, all modern steels will function quite well for most users, so you may want to consider spending more time examining other aspects of the pocket knife, such as how the knife functions and other characteristics.