When choosing the best handmade knives you should pay particular attention to the type of steel used in the knife. In addition to the geometry and design of the edges, blade steel is a critical element that determines how a knife performs. Steel is essentially an alloy (i.e., a mixture) of carbon and iron that is often enriched with other elements to improve certain properties depending on the desired application.
In the knife industry, different types of steel are made by varying the types of additive elements and also how the blade is rolled and heated (i.e., the finishing process). Consult our Knife Steel composition for more information about these elements.
Ultimately, the different types of steel used in knife blades each have a different degree of these five main characteristics:
Hardness is the ability to resist deformation when exposed to stress and applied forces. Hardness in knife steel is directly correlated to strength and is generally measured using the Rockwell C scale (also known as “HRC”).
Toughness is the ability to withstand damage such as cracks or chips in the event of impact or “sudden loads”. Chipping is the biggest enemy of a knife and never easy to repair. There are a number of different ways to measure toughness (i.e., Charpy, Izod), so it is less standardized than the hardness when it comes to blades. In general, the harder the steel, the less likely it is.
Abrasion resistance is the ability of the steel to resist damage due to abrasion and abrasion wear. Abrasion wear occurs when harder particles pass over a softer surface. Adhesive wear occurs when dirt is detached from one surface and attached to the other. Abrasion resistance generally correlates with the hardness of the steel but is also strongly influenced by the specific chemistry of the steel. In steels of equal hardness, the steel with larger carbides (think of microscopic, hard, wear-resistant particles) will typically resist wear better. However, hard metal can become brittle and crack, which reduces toughness.
Corrosion resistance is the ability to resist corrosion, such as rust caused by external elements such as humidity, moisture and salt. Note that high corrosion resistance means sacrifice in overall edge performance.
Edge retention indicates how long the blade retains its sharpness when exposed to periods of use. This is what everyone is talking about nowadays, but unfortunately edge retention measurement does not have any defined set of standards and so much of the data is subjective. For me, edge resistance is a combination of wear resistance and an edge that is resistant to deformation.
Unfortunately, the “best knife language” is not simply a matter of maximizing each of the above properties … it’s a tradeoff. The biggest consideration is balancing strength or hardness with toughness. Some knives can be made exceptionally hard, but will shatter or crack if dropped on a hard surface. Conversely, a blade can be extremely strong and able to bend, but will have difficulty keeping it sharp. In short, the stuff that makes steel strong (high amount of carbon / carbides) generally lowers toughness. Also note that the term “stainless steel” is generally misleading, since most types of steel will show some sort of discoloration if they are exposed to the elements long enough. By knowing how to use the knife, you can generally determine the best sample for your situation.
Common Knife Steel Types
The most common types of sheet steel generally fall into the following categories:
Tool Steel – mainly hard steel alloys used in cutting tools. Some popular steels in this group include the CPM series from D2, O1 and Crucible (i.e., CPM 3V) plus more advanced HS steels such as M4.
Carbon Steel – generally made for rough use where toughness and durability are important. Common in survival knives and cutting blades. They take a sharp edge and are relatively easy to sharpen. The interaction is more susceptible to corrosion due to the low chromium content. The most popular carbon knife steel is 1095.
Stainless Steel – basically carbon steel with added chromium to resist corrosion and other elements that increase performance, but usually at the expense of inferior toughness. Easily the most popular category today for EDC knives and includes the steels 400, 154CM, AUS, VG, CTS, MoV, Sandvik and Crucible SxxV. Note that in order to qualify as a genuine stainless steel, there must be at least 13% chromium.
What about Damascus steel?
Damascus steel comes from the Middle East from countries such as India and Pakistan, where it was first used in good old “BC” times. It is immediately recognizable because it has a swirling pattern caused by the welding of two different steels and so often referred to as “pattern welded” steel (not to be confused with Wootz steel that only looks in appearance). There are many myths about the power and potential of Damascus steel, but nowadays it is largely popular because of its aesthetic beauty. Usually only for collectors.
Remember, blade isn’t everything. Knife buyers have to be careful that they get caught up in researching the perfect steel type, because this is not the only thing that determines how a knife will perform. Steel analysis has become somewhat scientific, that you can easily get caught in the maze of statistics. Please note: just because a knife is made from the premium or high-end steels above does not automatically mean that it is “better” than the lesser steels. The heat treatment techniques used by the manufacturer, as well as the design of the blade itself, play a major role in the final result of the blade performance!