CPM S35VN vs M390 Knife Steel Comparison

Below is a comprehensive look at CPM-S35VN and M390, two popular premium steels in the knife world. Whether you are into bushcraft, EDC (everyday carry), kitchen tasks, or tactical applications, understanding the nuances of these steels will help you choose the best option for your needs. In discussing both steels, we’ll also touch on additional context (such as CPM-S35VN’s evolution from S30V, similar steels to M390, and recommended sharpening tips) to give you a complete picture.

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1. INTRODUCTION

Both CPM-S35VN and M390 are high-end, powder metallurgy steels known for their well-rounded performance characteristics. They have become favorite choices among custom knife makers and production brands alike, including popular names like Chris Reeve Knives (often using S35VN) and Benchmade or Zero Tolerance (well-known for M390). In this article, we will delve into their chemical composition, typical hardness ranges, heat-treatment intricacies, performance attributes (edge retention, toughness, corrosion resistance, and more), as well as practical usage scenarios and cost considerations.

Note:
• CPM-S35VN was developed as an improvement over CPM-S30V, with the addition of niobium to enhance toughness and ease of manufacture.
• M390 has near equivalents in steels like CPM 20CV and CTS-204P, which offer very similar chemical compositions and performance.

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2. CPM-S35VN STEEL OVERVIEW

2.1 Chemical Composition

CPM-S35VN is a stainless steel produced by Crucible Industries using powder metallurgy. It was designed to improve upon CPM-S30V by adding niobium, which refines the steel’s grain structure and increases overall toughness. Its approximate composition is:
• Carbon (C): 1.38% – Contributes to hardness and edge retention.
• Chromium (Cr): 14% – Responsible for corrosion resistance and added wear resistance.
• Molybdenum (Mo): 2% – Helps with hardness, toughness, and pitting resistance.
• Vanadium (V): 3% – Aids in edge retention and wear resistance.
• Niobium (Nb): 0.5% – Refines grain structure by forming niobium carbides, improving toughness and hardness.

2.2 Typical Hardness (Rockwell C) Ranges and Practical Implication

CPM-S35VN is commonly hardened to around 58–61 HRC, though some makers may push it as high as ~62 HRC. At this range:
• The steel maintains “good” toughness, capable of resisting chipping under normal use.
• Edge retention remains “good” and consistent over various cutting tasks.
• The steel is not overly difficult to sharpen at home or in the field, particularly if you use quality sharpening stones.

2.3 Key Performance Characteristics

• Corrosion Resistance: CPM-S35VN has very good corrosion resistance, making it suitable for humid or wet environments.
• Toughness: Recognized as having “good” toughness; it is less prone to chipping than some other high-carbide steels.
• Edge Retention: Provides a long-lasting edge—rated as “good” in this domain.
• Ease of Sharpening: Considered “good”; most users can re-sharpen this steel effectively with standard or ceramic sharpening stones.

2.4 Detailed Alloy Element Effects

• Carbon: Enhances hardness and contributes to edge-holding ability.
• Chromium: Boosts corrosion resistance and forms chromium carbides, which improve wear resistance.
• Molybdenum: Further improves hardness and corrosion resistance.
• Vanadium: Helps create small, hard vanadium carbides that increase wear resistance and refine grain structure.
• Niobium: Improves ductility and grain refinement, contributing to overall toughness and forming niobium carbides, which add a modest wear-resistance boost.

2.5 Heat Treatment Nuances and Forging

CPM-S35VN is relatively more forgiving than some highly alloyed steels during heat treatment. However, consistent temperatures and soak times are still critical for maximizing its properties. While not typically prone to severe warping or cracking, a proper normalizing cycle or careful temperature control is recommended for custom makers who forge or do differential heat treatments.

2.6 Patina Formation and Protective Coatings

As a stainless steel with “very good” corrosion resistance, CPM-S35VN does not easily form a patina. In normal use, it typically remains shiny and is unlikely to darken significantly through oxidation. Protective coatings (such as PVD or Cerakote) are uncommon because the steel itself is quite resistant to rust; however, some makers still use coatings for aesthetics or extra corrosion resistance in extreme environments.

2.7 Ideal Uses and Why Pick CPM-S35VN Over Others

If you want a steel that balances good edge retention with ease of sharpening and decent toughness, CPM-S35VN is an excellent choice. It is well-suited for EDC knives, bushcraft tasks that require a sturdy edge, or even kitchen knives where moderate toughness and corrosion resistance are valuable. CPM-S35VN appeals to those who need a do-it-all steel without worrying about constant maintenance or specialized sharpening equipment. Major brands like Chris Reeve Knives often use CPM-S35VN for its reliable performance.

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3. M390 STEEL OVERVIEW

3.1 Chemical Composition

M390 is a third-generation powder-metallurgy “super steel” produced by Böhler-Uddeholm. Its approximate composition is:
• Carbon (C): 1.9% – Contributes to high hardness and excellent edge retention.
• Chromium (Cr): 20% – Provides outstanding corrosion resistance and significant wear resistance.
• Molybdenum (Mo): 1% – Improves hardness and pitting resistance.
• Vanadium (V): 4% – Boosts wear resistance and edge stability.
• Tungsten (W): 0.6% – Adds hardness at high temperatures and further refines grain structure.
• Silicon (Si): 0.7% – Aids deoxidation during steelmaking and can add toughness in small amounts.
• Manganese (Mn): 0.3% – Minor contribution to hardenability.

(Note: M390 is closely related to CPM 20CV and CTS-204P, which have nearly identical chemical compositions.)

3.2 Typical Hardness (Rockwell C) Ranges and Practical Implication

Knife makers usually harden M390 between 60–62 HRC, though specialized protocols can push it to ~63–64 HRC. At that range:
• It excels in wear resistance—the steel is known for holding a sharp edge longer.
• Toughness is “fair”; while not prone to catastrophic failure at normal use, it is less tough than more shock-resistant steels.
• Harder edges demand a bit more care when sharpening but reward the user with exceptional cutting longevity.

3.3 Key Performance Characteristics

• Corrosion Resistance: M390 offers “excellent” corrosion resistance, among the highest in stainless cutlery steels.
• Toughness: Regarded as “fair” in the toughness department—adequate for common cutting tasks, though not the best for repeated, heavy-impact chores.
• Edge Retention: Known for “very good” (often top-tier) edge retention, M390 stands out in holding a keen edge for a long time.
• Ease of Sharpening: Generally “good.” Though it is a high-carbide steel, modern sharpening stones (especially diamond or ceramic) handle it well—use these tools for best results.

3.4 Detailed Alloy Element Effects

• Carbon: Primary driver of hardness and longevity of the cutting edge.
• Chromium: Extremely high content offers top-tier rust resistance.
• Molybdenum & Vanadium: Create multiple carbide types, increasing wear resistance significantly.
• Tungsten: Enhances grain refinement and high-temperature strength.

3.5 Heat Treatment Nuances and Forging

M390 requires precise temperature control to achieve its full potential. The steel is best processed in a vacuum or with protective atmospheres to reduce decarburization and ensure even carbide distribution. It is not commonly hand-forged by custom makers (due to its extreme alloy content), but if forging is attempted, it requires carefully monitored normalizing cycles and ramped heating to reduce the risk of warping or cracking.

3.6 Patina Formation and Protective Coatings

For practical purposes, M390 will not develop a patina in normal usage because of its “excellent” corrosion resistance. If you desire a darker finish for aesthetic reasons, you can opt for coatings like DLC (Diamond-Like Carbon) or Cerakote, but these are typically not required for rust prevention.

3.7 Ideal Uses and Why Pick M390 Over Others

For users who demand outstanding edge retention and corrosion resistance, M390 is a standout choice. This steel is popular in premium folders, tactical blades, and high-end kitchen knives, especially for those who want minimal maintenance and industry-leading sharpness retention. M390 also appears in brands like Benchmade or Zero Tolerance. It is a favorite among collectors who appreciate “super steels” with advanced properties.

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4. SIDE-BY-SIDE COMPARISON

Below is a quick reference summary of CPM-S35VN vs. M390:

	CPM-S35VN	M390
Corrosion Resistance	Very Good	Excellent
Toughness	Good	Fair
Edge Retention	Good	Very Good
Ease of Sharpening	Good	Good (best with diamond/ceramic)
Typical Hardness (HRC)	~58–61 (up to ~62 possible)	~60–62 (up to ~63–64 possible)
Patina Formation	Highly unlikely	Highly unlikely
Cost & Availability	Slightly lower cost, widely available	Usually higher cost, widely available

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5. REAL-WORLD PERFORMANCE SCENARIOS

5.1 Bushcraft and Survival

• CPM-S35VN: With good toughness and ease of sharpening, it is well-suited for batoning wood, carving, and bushcraft chores where you might not have specialized sharpening tools.
• M390: Excellent edge retention is beneficial for extended wilderness outings, but the comparatively lower toughness means you should be mindful of hard impacts on the blade’s edge.

5.2 EDC (Everyday Carry)

• CPM-S35VN: An outstanding general-purpose EDC steel. Easy to touch up on a pocket stone, resistant to rust from sweat or humidity, and tough enough for daily tasks.
• M390: Ideal if you want a pocket knife that remains razor-sharp for weeks of typical usage without frequent honing.

5.3 Kitchen Use

• CPM-S35VN: Very good for home kitchen knives—less risk of micro-chipping and simpler to sharpen.
• M390: Superior for professional settings or heavy kitchen use where you need extended edge life but can still handle specialized sharpening methods (diamond or ceramic stones).

5.4 Tactical or Defensive

• CPM-S35VN: Good choice if you need a robust blade that can handle unexpected impacts.
• M390: Offers incredible sharpness and corrosion resistance; just be cautious of potential brittle spots if heavily impacted.

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6. COST, AVAILABILITY, AND MAINTENANCE

CPM-S35VN typically commands a premium price over more basic steels, but it is still somewhat more affordable than M390. M390 often comes in at a higher cost, reflecting its specialized powder metallurgy formulation and advanced properties. Both steels have broad availability in the knife market, from custom blades to mid-range and high-end production knives.

Maintenance for both is relatively straightforward. A light coat of oil or a quick wipe-down after use will keep rust at bay, though M390 is less prone to corrosion than CPM-S35VN due to its higher chromium content. Routine honing will help maintain the blade’s edge, but when you do need a full sharpening session—especially with M390—diamond or ceramic stones are strongly recommended to expedite the process and handle the steel’s higher carbide volume efficiently.

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7. PROS AND CONS

7.1 CPM-S35VN

Pros:
• Good balance of toughness, corrosion resistance, and edge retention
• Easier to sharpen compared to many other premium steels
• More forgiving in heat treatment and usage
• Typically lower cost than M390

Cons:
• Edge retention is “only” good, not at the extreme end of super steels
• Still costlier than entry-level stainless steels

7.2 M390

Pros:
• Superb edge retention and excellent corrosion resistance
• Crisp cutting performance for a prolonged period
• Widely respected as one of the top “super steels”
• High hardness potential without excessive brittleness

Cons:
• Fair toughness means caution with very hard impacts
• More expensive and requires more specialized sharpening tools (diamond, ceramic)
• Heat treatment can be more complex to perform correctly

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8. CONCLUSION AND RECOMMENDATIONS

CPM-S35VN and M390 are both stellar performers in the knife steel arena, but they cater to slightly different user preferences:

• CPM-S35VN:
– Ideal for users seeking a solid balance across toughness, corrosion resistance, edge retention, and ease of sharpening.
– Great for bushcraft, EDC, and general-purpose blades where you cannot always access specialized sharpening equipment.
– Offers affordability relative to other premium steels while still providing excellent performance (often showcased by brands like Chris Reeve Knives).

• M390:
– Perfect for those who prioritize “very good” edge retention and “excellent” corrosion resistance and who are willing to invest in higher cost and more involved sharpening methods.
– Excels in EDC, professional kitchen settings, or tactical knives that demand minimal maintenance and top-tier performance (as seen with brands like Benchmade or Zero Tolerance).
– The steel of choice for collectors who want the absolute best in modern metallurgy for their blades.

Ultimately, the decision comes down to personal preference, anticipated use, and budget. If you place a premium on toughness and simpler sharpening but still want a high-end steel, CPM-S35VN is a great pick. If extreme edge retention and corrosion resistance outrank other concerns (and you have a diamond sharpening setup on hand), M390 is likely your go-to. Both are excellent steels that should satisfy enthusiasts and collectors alike for years to come.

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9. FREQUENTLY ASKED QUESTIONS (FAQ)

Q1. Is M390 harder to sharpen than CPM-S35VN?
M390 often contains more and harder carbides, making it slightly more challenging to sharpen. Using diamond or ceramic stones helps mitigate this difficulty. CPM-S35VN is generally easier to sharpen in the field with standard sharpening tools.

Q2. Can CPM-S35VN or M390 rust?
Both are stainless steels, but M390’s higher chromium content (around 20%) generally gives it superior corrosion resistance. CPM-S35VN will not rust easily, but if you neglect basic maintenance (cleaning and drying), it’s slightly more prone to rust than M390.

Q3. Are there steels equivalent to M390?
Yes. CPM 20CV and CTS-204P are very close in composition and performance. They are sometimes used interchangeably with M390 by different knife manufacturers.

Q4. Can CPM-S35VN or M390 be forged by custom makers?
CPM-S35VN is somewhat more forgiving and can be forged by experienced smiths with proper controls. M390’s extreme alloy content makes it significantly more challenging to forge, so it’s more commonly stock-removal rather than forged.

Q5. Which steel should I choose if I’m on a budget?
CPM-S35VN knives are typically a bit more affordable among premium steels, making them a solid choice if you want great performance without the higher cost of M390.

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By keeping these considerations in mind and aligning them with your specific needs—be it everyday carry, bushcraft, or professional culinary use—you’ll be well-prepared to invest in a blade that offers long-lasting satisfaction.