Types of Steel in Knives
A knife is only as good as the materials that comprise it, and an otherwise awesome blade can be held back if it’s built of cut-rate stuff. In this article, we will focus specifically on the different kinds of steel used in knives and how they affect their functionality.
What Materials Make Up Steel?
At its heart, steel is a relatively simple substance, comprised almost entirely of iron and a tiny percentage of carbon and some trace elements. However, it’s that little percentage that determines much of a steel’s character. The most important material in steel other than iron is by far carbon. Ranging from thousandths of percent to over two percent, it contributes hardness, tensile strength, and blade retention. Other common elements include the following:
Different amounts of these elements will alter the steel’s performance, making changes primarily in its hardness, toughness, corrosion resistance, ability to hold an edge, and ease of sharpening.
What Are the Four Main Steel Categories?
The different component parts of steel translate into four main categories. Please note, though, that chemical composition isn’t the determiner of steel type; the way in which the metal gets worked also plays a role in what kind of steel you’ll end up with. Keeping that in mind, the first and best-known kind of steel is stainless steel. Relatively inexpensive and the steel type with the greatest resistance to rust, it contains at least 10.5 percent chromium. In addition to resisting rust, it’s brilliantly shiny, more malleable than other steels, and easier to sharpen.
High-carbon steel gains its name from — you guessed it! — the relatively large amount of carbon it contains, usually anywhere from 0.6 percent to two percent. This offers several advantages, such as high strength and the ability to hold an edge. However, it is prone to rusting and may prove difficult to sharpen.
D2 steel most often ends up used in tools and machining equipment due to its inherent toughness. While it does have some rust resistance, it’s far more prone to oxidation than stainless steel and can prove difficult to sharpen.
Damascus steel is unique amongst all the different types of steel. This ancient formulation originated in the Middle East and even migrated to Japan hundreds of years ago. But as firearms supplanted swords, the mystery of its formulation was lost, only being recovered in the late 20th century. Today’s craftsmen have modified it slightly, which results in a technique that accurately mirrors its oil-slick appearance. Smiths begin with carbon-rich steel that usually contains not-insignificant amounts of nickel, silicon, manganese, sulfur, and phosphorous. This steel gets stacked with multiple layers of metal and heated at lower-than-normal temperatures, then hammered and folded multiple times. The result is an incredibly unique kind of patterned steel. The main use of Damascus steel is decorative.
Specific Steel Types
It’s one thing to speak about broadly about steel characteristics and how these categories perform in general. It’s quite another to show the ways in which individual steel types function, because each broad category contains a large number of specific steels that all work a little differently. In this section, we’ll explain the differences between common kinds of knife steel and into which category they fall. We will also focus primarily on stainless steel and carbon steel with a few examples in the D2 steel category. Read our article on Damascus steel patterns to learn more about that particular kind of blade. Finally, please note that these are far from exhaustive lists. The world of steel types is complex and always expanding!
Examples of Stainless Steel Types
420: One of the most common kinds of stainless steel, 420 is tough, easy to sharpen, corrosion resistant, and quite inexpensive. However, it doesn’t hold an edge for very long and will require regular sharpening.
440: An older stainless steel that was once considered a premium material, 440 steel comes in three different formulations: 440A, 440B, and 440C. All three exhibit slightly more edge retention thatn 420, but are also somewhat less tough.
ZDP-189: This type of steel primarily finds use in Japanese knives. It contains large amounts of carbon and also up to one-fifth of it is comprised of chromium. A truly premium steel, it carries with it a heft price tag to match.
VG-10: Combining some of the properties of carbon steel with stainless steel, VG-10 creates a hard, durable blade that won’t rust. It contains 15 percent chromium and one percent carbon, as well as significant amounts of molybednum, vanadium, and cobalt.
Examples of High-Carbon Steel
1095: This is the quintessential example of high-carbon steel. Its carbon and manganese content allows to hold an edge while remaining relatively easy to sharpen. It’s remarkably wear resistant, but it will rust if not cared for.
5160: This steel is very similar to 1095, but it also contains a fair amount of chromium. While it’s not particularly resistant to rust, it’s super tough and can stand up to a lot of abuse.
52100: A super-hard steel originally used for industrial equipment, it excels at holding an edge. Rust is an issue, though.
L6: A steel that exhibits the trademark hardness and sharpness associated with high carbon. Often found in cutlery.
D2 Steel and Examples of Industrial-Grade Steel
D2: Though it is sometimes used to describe an entire category, D2 is its own kind of steel. Added chromium protects against rust, and it stays sharp while resisting wear. Very difficult to sharpen.
A2: Super-tough steel with lower wear resistance. Typically used in fighting knives. Often coated to safeguard against oxidation.
CPM M4: High molybdenum (2.95 percent) and vanadium (3.85 percent) combined with 1.35 percent carbon and five percent chromium creates a metal that’s as appropriate for tools as it is for knives. Extremely durable.
TacKnives uses many different kinds of steel in our OTFs. Review our inventory to find the ideal blade for your use case.