K390 Steel: Is it a Good Knife Steel?

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If you are looking for high-end steel with high resistance to wear and abrasion, K390 can be your best choice. Spyderco has many EDC models in their Signature series made of this steel. Let’s look at its properties and benchmark its performance against other steels.

What is K390 Steel?

Spyderco Endura 4 Lightweight Folding Knife with K390 Premium Steel Blade and Blue Durbale FRN Handle - PlainEdge - C10FPK390

K390 is German steel developed by Bohler for use in cold work applications and parts subjected to abrasive wear at the time of processing plastics. It refers to a type of advanced tool steel that Bohler makes using its exclusive particle metallurgy process, also known as the MicroClean technology.

This modern alloy mix was formulated to ensure high compressive strength and extreme wear resistance required in blanking, cutting, and punching industrial operations.

Unusually, its fine and homogeneous microstructure is responsible for its great machinability and ease of heat treatment. These properties contribute to great toughness and outstanding edge retention in terms of blade steel.

Chemical Composition

The K390 tool steel contains less amount of chromium and is not stainless. It is too less than the threshold level required to make it stainless. Following are the elements that make up this tool steel:

  • 2.47% Carbon: For better hardness as well as resistance to wear as well as corrosion
  • 4.20% Chromium: For improved tensile strength, edge retention, wear resistance, and corrosion resistance
  • 3.80% Molybdenum: For more strength, hardness, and machinability
  • 9.00% Vanadium: For improved hardenability as well as wear resistance
  • 2.00% Cobalt: For the boosted effect of each element that makes up this steel
  • 1% Tungsten: For improved hardness as well as wear resistance
  • 0.55% Silicon: For boosted strength
  • 0.40% Manganese: For reduced brittleness and better hardness as well as forgeability

In terms of composition, K390 is a modified form of A11, another tool steel made for cold work applications. However, the major difference is that the Bohler steel is tougher than the A11.


On the Rockwell scale of hardness, K390 has a 64-65 HRC rating, which means that it is very hard steel. However, if you compare this rating range with options such as Maxamet, it will seem to be a bit low. Despite this, the German steel has some great properties based on this hardness level, due to which it is ideal for designing high-quality knives.


Spyderco Endura 4 Lightweight Folding Knife with K390 Premium Steel Blade and Blue Durbale FRN Handle - PlainEdge - C10FPK390

  • Good Toughness: The harder the steel, the less is its ability to keep lateral forces and impacts at bay. So, based on this fact, you will infer that K390 is less tough steel, as it has a high hardness level. While it is technically correct, it does not mean that K390 is less reliable in terms of toughness. It is still tough enough to endure the impact of most tough cutting tasks. The credit for this goes to the third-generation particle metallurgy of Bohler. Still, you need to ensure that you do not use your K390 knife for tougher tasks such as batoning. Otherwise, it will break or deform.
  • Excellent Edge Retention: It can hold a sharp edge for a longer period than usual. This is expected from any hard steel and boasts high carbon and vanadium contents. In addition, it contains a large amount of vanadium carbides that directly contribute to improved edge durability. Thus, a K390 blade holds its edge better and for longer.
  • Terrific Wear Resistance: The hardness level of any steel contributes to its edge retention ability and wear resistance power. The higher the hardness, the better are both abilities. As this Bohler steel has a high hardness level, it resists wear well. This is also attributed to a high quantity of vanadium in the alloying mix. As a result, your K390 knife will not get damaged or show any signs of wear and tear for years to come.
  • Okay Corrosion Resistance: Due to the lack of enough chromium, K390 is not great in resisting stains, rust, or corrosion. Nevertheless, 4.2% chromium still gives some considerable resistance power. That said, you are required to take good care of this steel knife to keep rust and corrosion at bay. If stainless steel and corrosion resistance are what you are looking for, this tool steel is not what you want.
  • Ease of Sharpening: The harder the steel, the more difficult it is to sharpen. If this is what you are thinking for K390, you are right. It is not easy to sharpen any edge made using this steel. However, this does not mean that you will be unable to sharpen it well once it becomes dull. To gain a super-sharp edge, you need to use a more advanced sharpener, and we recommend diamond stone.

Comparison With Other Knife Steel Options

Let’s now compare K390 tool steel with its peers based on its ease of sharpening, toughness, and resistance to corrosion and rust.

K390 vs. S90V

K390 is considered equivalent of S90V, as both offer similar properties such as great toughness, high hardness, and terrific edge retention. This is attributed to the high vanadium amount of 9% in both grades. Even the price range for both is the same. However, S90V is stainless, as it has enough and higher chromium content. So, you can expect better corrosion resistance.

K390 vs. VG10

VG10 wins over K390 in better corrosion resistance, ease of sharpening, and toughness. However, the Bohler steel is better at resisting a sharp edge.

K390 vs. M390

M390 is stainless, which means better corrosion resistance than the tool steel. M390 is also tougher and easier to sharpen. However, K390 wins in terms of edge retention and wear resistance.

So, is K390 Steel Good?

K390 is a good knife steel option, as it will retain its cutting edge and continue to cut for longer without wear and tear. However, the corrosion resistance isn’t great, and you will need to take good care of it if you are planning to use it in humid environments.