CPM S60V vs CPM S90V Knife Steel Comparison

Introduction

When it comes to premium knife steels, enthusiasts often find themselves comparing various high-end alloys to see which best meets their needs. Two popular options are Crucible Industries’ CPM-S60V (historically referred to as CPM-440V) and CPM-S90V, both of which are powder metallurgy steels known for their remarkable performance. In this comprehensive guide, we’ll explore critical aspects—chemical composition, hardness ranges, heat-treatment nuances, and real-world performance (edge retention, toughness, corrosion resistance, and ease of sharpening). We’ll also address practical usage scenarios such as everyday carry (EDC), bushcraft, kitchen, survival, or tactical applications, helping you decide which steel aligns with your requirements.

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1. Chemical Composition and Detailed Alloy Element Effects

Understanding the alloy elements in CPM-S60V and CPM-S90V is crucial to appreciating their performance. Although both originate from Crucible Particle Metallurgy (CPM) processes, each has a distinct chemical profile that influences hardness, wear resistance, and corrosion resistance.

CPM-S60V (CPM-440V)

• Carbon (~2.15%): Contributes to hardness and edge retention.
• Chromium (~17%): Elevates corrosion resistance and helps with hardness.
• Manganese (~0.4%): Assists in achieving hardness and improves hot workability.
• Molybdenum (~0.4%): Adds strength at high temperatures and improves hardenability.
• Silicon (~0.4%): Slightly increases toughness and helps deoxidize the steel during production.
• Vanadium (~5.5%): Significantly enhances wear resistance and edge retention through the formation of vanadium carbides.

CPM-S90V

• Carbon (~2.3%): Supports higher achievable hardness and excellent edge retention.
• Chromium (~14%): Supplies very good corrosion resistance and hardness properties.
• Molybdenum (~1%): Improves strength at elevated temperatures and aids hardenability.
• Vanadium (~9%): Further boosts wear resistance and edge retention, making it one of the top performers in this category.

Element Effects Explained

• Carbon: Higher carbon content increases hardness and edge retention but can lead to brittleness if heat treatment is not spot-on.
• Chromium: Primary factor for stainless capability (13%+). In these steels, it also promotes hardness and durability.
• Vanadium: Forms extremely hard carbides that significantly enhance wear resistance and edge retention. However, the higher the vanadium, the more challenging it becomes to sharpen.
• Manganese, Silicon, and Molybdenum: Support toughness, refine grain structure, and strengthen the steel, especially under high temperatures.

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2. Typical Hardness (Rockwell C) Ranges and Practical Implication

Both CPM-S60V and CPM-S90V are usually hardened to the high 50s or low 60s on the Rockwell C scale:

• CPM-S60V: Commonly in the 59–61 HRC range.
• CPM-S90V: Typically in the 60–62 HRC range.

Practical Implications

• High Hardness: Contributes to excellent wear resistance and prolonged edge retention.
• Potential Brittleness: As the hardness level rises, toughness can decrease if the heat treatment isn’t tuned carefully.
• Sharpening Difficulty: Harder steels demand higher-quality sharpening equipment and more skill—often diamond or ceramic stones.

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3. Heat-Treatment Nuances and Forging

Both CPM-S60V and CPM-S90V are advanced stainless steels high in carbon and vanadium, requiring precise and carefully managed heat-treatment protocols.

• Heat-Treatment Complexity

  • Best performed in well-controlled furnaces using inert atmospheres or vacuum conditions to minimize oxidation.
  • Critical steps include accurate austenitizing, cryogenic quenching to transform retained austenite, and one or more tempering cycles.

• Warping and Cracking Risks

  • Although catastrophic warping is not common, uniform heating and cooling are crucial due to the steels’ high wear resistance.
  • Extended soak times and multiple tempering cycles often help reduce internal stress.

• Forging

  • As powdered metallurgy steels, both are more frequently approached via stock removal rather than forging.
  • If forging is attempted, it must be done at strictly controlled temperatures to avoid micro-cracking, given the steels’ high carbide content.

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4. Performance Comparison: CPM-S60V vs. CPM-S90V

Below are the key performance factors that knife enthusiasts usually consider:

4.1 Corrosion Resistance

• CPM-S60V: Excellent corrosion resistance due to ~17% chromium. It’s particularly well-suited to humid or wet environments.
• CPM-S90V: Very good corrosion resistance, though slightly lower chromium (14%) means it’s a notch below S60V in extremely harsh or salty conditions.

4.2 Toughness

• CPM-S60V: Fair toughness. Heat-treatment optimization is critical since higher carbon and vanadium can reduce impact resistance.
• CPM-S90V: Also fair, designed more for wear resistance than impact absorption.

4.3 Edge Retention

• CPM-S60V: Very good edge retention. It holds a keen edge for extended periods thanks to its vanadium carbides.
• CPM-S90V: Excellent edge retention—one of the best among popular stainless powders. Its higher vanadium (~9%) really elevates its wear resistance.

4.4 Ease of Sharpening

• CPM-S60V: Fair. It still needs quality abrasives but is somewhat more forgiving than ultra-hard modern steels.
• CPM-S90V: Poor in terms of ease, as it’s notoriously tough to sharpen. Premium diamond or ceramic stones and a solid sharpening technique are a must.

Comparison Table

Property	CPM-S60V	CPM-S90V
Corrosion Resistance	Excellent	Very Good
Toughness	Fair	Fair
Edge Retention	Very Good	Excellent
Ease of Sharpening	Fair	Poor
Typical HRC Range	59–61	60–62

Note: Blade geometry (e.g., thinness behind the edge, edge angle) also plays a critical role in both performance and sharpening difficulty.

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5. Real-World Applications

• Bushcraft and Survival
  Neither steel is ideal for heavy-impact tasks like repetitive batoning or chopping. However, for carving, feather-sticking, and other standard bushcraft needs, both perform well. S90V will hold its edge longer, but S60V is easier to maintain in the field.

• Everyday Carry (EDC)
  Excellent for those who frequently cut cardboard, rope, or other fibrous materials. S90V is appealing if you don’t mind less frequent but more challenging sharpening sessions. S60V offers easier field touch-ups and may be more forgiving in wet or humid locales.

• Kitchen Use
  In a moisture-heavy environment, both steels shine. S60V’s higher chromium content makes it slightly more corrosion-resistant. However, the repetitive resharpening often required for kitchen knives can be more demanding with S90V.

• Tactical and Military
  Corrosion resistance and long-lasting edges are usually paramount. Both steels fit, though S90V demands advanced sharpening know-how. In wet, corrosive environments, S60V’s slightly higher rust resistance can be beneficial.

• Collector’s Pieces
  CPM-S60V and CPM-S90V are highly regarded in custom or limited-edition collections. S90V in particular draws attention from enthusiasts seeking a top-tier edge-holding solution.

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6. Patina Formation and Protective Coatings

Due to their high chromium content, these steels are categorized as stainless and rarely develop a patina.

• Patina Formation
  Virtually nonexistent under normal conditions. If any discoloration occurs, it’s usually surface-level oxidation rather than a true patina.

• Protective Coatings
  Largely unnecessary. Some manufacturers do apply coatings for aesthetic reasons or for additional safeguarding in saltwater environments, but the base steels already offer outstanding corrosion resistance.

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7. Cost, Availability, and Maintenance Considerations

• Cost

  • CPM-S90V tends to be pricier because of its higher vanadium content and extreme performance.
  • Both are premium options, so more budget-oriented buyers might look to steels like 154CM or S35VN for a balance of price and performance.

• Availability

  • CPM-S90V is less common than some other Crucible favorites like S30V or S35VN, partly due to its challenging working properties and higher material costs.
  • CPM-S60V (CPM-440V) is somewhat older and overshadowed by modern steels (e.g., S30V, S35VN) and can be harder to source. That said, it still appears in select production models and custom pieces.

• Maintenance

  • Both steels require diamond or high-quality ceramic abrasives for sharpening.
  • You may need professional sharpening services if you lack the right tools or training.
  • Regular cleaning and drying is still advisable, even though rust spots are unlikely.

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8. Pros and Cons

CPM-S60V

Pros

• Excellent corrosion resistance
• Very good edge retention
• Slightly more forgiving during sharpening compared to S90V
• Can be less expensive than S90V

Cons

• Fair toughness—not ideal for heavy impact tasks
• Still more challenging to sharpen than simpler steels like 440C
• Less commonly found in newer production knives

CPM-S90V

Pros

• Outstanding edge retention—among the best in stainless steels
• Very good corrosion resistance
• Highly regarded by collectors and performance enthusiasts

Cons

• Difficult to sharpen (diamond stones recommended)
• Fair toughness—risk of chipping under severe abuse
• Commands a premium price and not as widely available

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9. Why Pick CPM-S60V or CPM-S90V Over Other Options?

Knife users gravitate toward these steels for their elite blend of wear resistance, corrosion resistance, and overall performance. They make sense if you:

• Want a blade that stays sharp through extensive cutting tasks (e.g., working with cardboard, rope, or fibrous materials).
• Operate in wet or humid conditions and require strong stainless properties.
• Seek a premium metallurgical pedigree that performs and also holds prestige in high-end or collectible knives.

If you need extreme toughness for continuous impact or easier sharpening, steels like CPM-3V, AEB-L, or well-known balanced options (like S30V, S35VN, or even S45VN) might be more suitable. For those curious about going beyond S90V in edge retention, CPM-S110V or S125V offer even higher wear resistance—though they are more challenging to work with and maintain.

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10. Conclusion and Recommendations

Both CPM-S60V and CPM-S90V belong to the upper echelon of stainless steels, offering superb edge retention, fair toughness, and excellent corrosion resistance. Your choice depends on budget, sharpening skills, and the environment in which you’ll use the knife.

• CPM-S60V

  • A strong pick if you value extra corrosion resistance and a more approachable sharpening experience than S90V.
  • Ideal for users who frequently encounter humid or wet conditions but still desire long edge life.

• CPM-S90V

  • Renowned for its industry-leading wear resistance and exceptional edge retention.
  • Perfect if you’re prepared to tackle the greater challenge of sharpening or have professional sharpening services at your disposal.

Ultimately, you can’t go wrong with either steel if you’re aiming for high performance. CPM-S60V offers a balanced path to excellent stainless properties with slightly less sharpening difficulty, while CPM-S90V stands out for its virtually unmatched edge-holding capabilities in a stainless platform. Choose the one that best fits your lifestyle, sharpening skills, and budget, and you’ll be rewarded with a top-tier blade that can handle demanding tasks without missing a beat.