K390 Steel: The Best Steel for High-Performance Knives?

If you are looking for premium quality Spyderco knives, you are likely to come across the K390 steel. It was developed as an alternative to Crucible’s CPM-10V. But, it has gained huge popularity for its outstanding properties and overall performance. Let’s explore the characteristics and properties of K390 steel and determine whether it is a good choice for the knife.

What is k390 Steel?

K390 steel is a  High-end Cold work tool steel developed by the German steel production BohlerUddeholm following the powder metallurgy process. It is a high-alloy, high-carbon steel known for its exceptional wear resistance and toughness. It is not stainless steel as it contains little amount of chromium in its composition. However, it has high amounts of Vanadium that contribute to its excellent toughness and incredible wear resistance. So it is commonly used in the knife industry for making cutting tools, barrels, slitters, coining, screws, and cold-forming operations.

Chemical Composition:

  • 2.47% of Carbon (C): Increases the edge retention, hardness and strength.
  • 4.20% of Chromium (Cr): Increases the hardness, tensile strength and corrosion resistance.
  • 3.80% of Molybdenum (Mo): Improves machinability and hardness.
  • 9.00% of Vanadium (V): Increase wear resistance and toughness and improves corrosion resistance.
  • 1.00% of Tungsten (W): Improves wear resistance and hardenability.
  • 2.00% of Cobalt (Co): Enhances the individual effects of other components.
  • 0.55% of Silicon (Si): Increases strength and heat resistance.

Physical Properties:

Hardness: On the Rockwell scale, its hardness rating is around 64-65 HRC which is considered very hard steel. However, that doesn’t mean it is not the hardest steel. There are so many other steels with better hardness available in the market. Its high amount of carbon, vanadium, and molybdenum helps this steel exhibit excellent hardness. Toughness: As we all know harder steel has lower toughness than others. However, it has decent toughness that is still tough enough to withstand high impact forces of most tough cutting tasks without chipping or breaking. In fact, it has better toughness than steel like K110, k340 and D2. All the credit goes to the compositions and third-generation particle metallurgy of Bohler. Edge Retention: Due to its high carbon and vanadium contents, it offers excellent edge retention. Moreover, it also contains a large amount of vanadium in its compositions which also boosts its edge retention. So knives made from this steel can hold a sharp edge for a long time without compromising its performance. Wear Resistance: This steel is also renowned for its exceptional wear resistance. Since its hardness level is extremely high, it also exhibits great wear resistance. The high vanadium content in the steel enhances its ability to resist wear and abrasion. Corrosion Resistance: While it is not considered stainless steel, it still offers a good level of corrosion resistance. It contains a sufficient amount of chromium that forms an oxide layer on the blade and prevents corrosion and maintains the steel’s longevity. Ease Of Sharpening: As already mentioned, it is extremely hard steel. So it is quite tough to sharpen the knives made from this steel. However, this doesn’t mean it can’t be sharpened at all. With the right technic and sharpening tools, you can sharpen it.

Advantages of K390 steel:

  • Optimal hardness: It exhibits a high level of hardness that is perfectly suitable for making different types of knives.
  • Superior Wear Resistance: It has outstanding wear resistance that maintains its sharpness for extended periods.
  • Impressive Toughness: Despite its high hardness, it also possesses impressive toughness. It can endure high-impact forces without chipping or breaking.
  • Fine Grain Structure: As it is produced through powder metallurgy, possesses a fine and homogeneous grain structure.

Disadvantages of K390 steel:

  • Difficult to sharpen: Due to its hardness, it is more challenging to sharpen compared to softer steels.
  • Expensive: Due to its superior performance and relative scarcity, you find it more expensive compared to other knife steels.

Heat Treatment of K390 Steel:

  • Preheating: Begin the process by preheating the steel to a temperature of around 1500-1550°F.
  • Austenitizing: Then heat the preheated steel to the austenitizing temperature.  Soak for 5 to 15 minutes at 2,150°F to get optimum wear resistance. Soak for 15 to 30 minutes at 2,050°F for the balance of wear resistance and toughness.
  • Quenching: Once the steel reaches the austenitizing temperature, perform a rapid quenching process to cool it down rapidly. Plate, air or medium oil quench to 125°F.
  • Tempering: After quenching, the steel is generally too hard and brittle for practical use. Temper it immediately at 1,000-1100°F. Hold at temperature for two hours before repeating the process three times for maximum results.

Is S90v Steel Sharper Than K390 Steel for Knives?

When comparing S90v VS M390 Steel Knives, one aspect to consider is sharpness. While both steels are highly regarded, S90v is known for its exceptional edge retention, making it a popular choice among knife enthusiasts. On the other hand, K390 steel is also renowned for its outstanding edge stability and toughness. Ultimately, the sharpness of a knife depends on various factors, including its geometry and the sharpening techniques used.

Applications and uses of K390 steel:

Due to its exceptional properties, it is commonly used for manufacturing a wide range of applications. Here are some common applications and uses:
  • Knives: It is used in various types of knives, including fixed-blade knives, folding knives, hunting knives, survival knives, and tactical knives.
  • Industrial Knives: This steel is also demanded for manufacturing industrial knives such as paper and pulp, plastic, packaging, textile, and woodworking.
  • Cutting Tools: Tools like saw blades, shearing blades, milling cutters, drills, punches, and dies are also made from this steel.
  • Blades for Power Tools: It is utilized in the production of blades for power tools such as circular saws, reciprocating saws, and bandsaws.

Comparison With Other Knife Steel Options:

K390 Steel Vs M390

Both steels are manufactured by the same company, but M390 Steel is stainless steel that offers slightly higher wear resistance and outstanding corrosion resistance. Moreover, it is easier to sharpen due to its hardness level. On the other hand, K390 is non-stainless steel that generally has higher toughness and better edge retention due to its higher vanadium carbide content.

K390 Steel Vs VG10

K390 steel offers significantly higher wear resistance, edge retention and toughness compared to VG10 steel. So it is commonly used to make pocket knives. On the other hand, VG10 steel has better corrosion resistance as it contains more chromium in its compositions. Moreover, it is slightly easier due to its lower hardness level. Not only that, it is relatively easier to maintain. So most users like this steel as their kitchen knife.

K390 Vs ZDP189

As ZDP189 steel contains higher amounts of carbon in its composition, it offers higher hardness and wear resistance. Both steels are renowned for their exceptional wear resistance. However, K390 offers higher toughness. So it can withstand heavy cutting tasks without chipping or breaking. Additionally, it contains a higher percentage of chromium that offers better protection against corrosion than ZDP189 steel.

K390 Steel Vs S30V

K390 steel exhibits higher wear resistance compared to S30V steel. This steel outperforms S30V steel in terms of toughness and edge retention. So knives made from this steel are more resistant to chipping and breaking under high-impact forces and maintain a sharp edge for an extended period. However, S30V steel offers better corrosion resistance and is slightly easier to sharpen due to its lower hardness level. Final Words: In conclusion, K390 steel has proven itself to be an excellent knife steel, offering exceptional wear resistance, impressive toughness, and long-lasting edge retention. Yes, it is true that it has a few potential drawbacks.  But despite all of this, it is highly demanding in the knife and tool industry. Whether you’re a professional chef or a knife enthusiast like me, you should try this knife steel. Then you can’t resist yourself to praise its outstanding performance.

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