M390 and S35VN are two of the most popular high-performance steels in the knife industry, widely used in premium knives for their excellent balance of properties. Both are produced through powder metallurgy, which ensures a fine grain structure and uniform carbide distribution.
However, they cater to slightly different needs, with M390 excelling in edge retention and corrosion resistance, while S35VN is known for its toughness and ease of sharpening.
This article provides a detailed comparison of these steels based on measurable scientific data such as chemical composition, edge retention (CATRA test results), toughness, hardness, and corrosion resistance. We will also explore their manufacturing processes, heat treatment requirements, real-world performance characteristics, and cost implications.
Composition Analysis
The chemical composition of a steel significantly affects its performance characteristics like hardness, toughness, wear resistance, and corrosion resistance. Below is a comparison of the compositions of M390 and S35VN:
| Element | M390 (%) | S35VN (%) |
|---|---|---|
| Carbon (C) | 1.90 | 1.40 |
| Chromium (Cr) | 20.00 | 14.00 |
| Vanadium (V) | 4.00 | 3.00 |
| Molybdenum (Mo) | 1.00 | 2.00 |
| Tungsten (W) | 0.60 | – |
| Niobium (Nb) | – | 0.50 |
Key Alloying Elements and Their Impact:
- Carbon: Higher carbon content in M390 (1.90%) contributes to its superior hardness and wear resistance compared to S35VN.
- Chromium: M390’s high chromium content (20%) gives it exceptional corrosion resistance, making it ideal for use in wet or salty environments.
- Vanadium: Both steels contain vanadium, which enhances wear resistance by forming hard vanadium carbides.
- Niobium: Unique to S35VN, niobium improves toughness by refining the grain structure and reducing carbide size.
Performance Metrics
Edge Retention (CATRA Test Results)
Edge retention is one of the most critical factors in knife performance, especially for tasks requiring prolonged cutting without frequent sharpening.
- M390: M390 has an excellent edge retention rating due to its high hardness and wear resistance from the fine distribution of vanadium carbides.
- S35VN: While S35VN also performs well in edge retention tests, it falls slightly behind M390 due to its lower carbon content and less aggressive carbide formation.
In CATRA tests (which measure the number of cuts a blade can make through a standardized medium before dulling), M390 consistently outperforms S35VN by approximately 10-15%, making it the better choice for users prioritizing long-lasting sharpness.
Toughness (Charpy Impact Values)
Toughness refers to a steel’s ability to resist chipping or breaking under impact.
- M390: Despite its high hardness, M390 has moderate toughness for a steel of its class but is more prone to chipping than S35VN under heavy use or lateral stress.
- S35VN: S35VN excels in toughness due to its refined grain structure and niobium content. It is less likely to chip or crack under impact, making it more suitable for applications where durability is crucial.
Charpy impact tests show that S35VN has up to 20% higher toughness than M390, making it more reliable for tasks involving prying or chopping.
Corrosion Resistance
Both steels offer excellent corrosion resistance due to their high chromium content; however, M390’s higher chromium percentage gives it an edge in more aggressive environments.
- M390: With 20% chromium, M390 excels in resisting rust and pitting even in saltwater conditions.
- S35VN: While still highly resistant to corrosion with 14% chromium, S35VN may require more care in extremely corrosive environments but will perform adequately for most everyday carry (EDC) applications.
Hardness Range (Rockwell C Scale)
Hardness directly impacts wear resistance and edge retention but can inversely affect toughness.
- M390: Typically hardened to between 60-62 HRC, M390 offers superior edge retention but can be more brittle.
- S35VN: Usually hardened to around 58-61 HRC, S35VN strikes a better balance between hardness and toughness, making it easier to sharpen while still holding an edge well.
Heat Treatment Considerations
The performance of both steels depends heavily on proper heat treatment protocols.
Optimal Heat Treatment Parameters
For both steels, heat treatment involves precise control over heating temperatures, quenching rates, and tempering cycles:
- M390:
- Austenitizing temperature: 2150°F (1177°C)
- Quenching medium: Oil or forced air
- Tempering temperature: Between 350°F – 500°F Proper heat treatment maximizes M390’s hardness while maintaining enough toughness to prevent chipping under normal use.
- S35VN:
- Austenitizing temperature: 1950°F – 2000°F (1065°C – 1093°C)
- Quenching medium: Oil or air
- Tempering temperature: Between 400°F – 600°F S35VN requires less stringent heat treatment compared to M390 due to its lower carbon content and simpler carbide structure.
Common Heat Treatment Challenges
M390’s high alloy content makes it more challenging to heat treat correctly; improper quenching or tempering can result in reduced toughness or excessive brittleness. In contrast, S35VN is more forgiving during heat treatment due to its balanced composition.
Real-World Performance Characteristics
Edge Stability
Edge stability refers to how well a steel maintains a fine cutting edge without rolling or chipping during use:
- M390: Due to its high hardness and fine carbide distribution, M390 offers excellent edge stability but may chip under heavy lateral stress.
- S35VN: With better toughness than M390, S35VN provides good edge stability with less risk of chipping during tough tasks like batoning or prying.
Sharpening Behavior
Sharpening difficulty is often cited as a drawback of harder steels:
- M390: Known for being difficult to sharpen due to its high wear resistance; diamond stones are recommended for best results.
- S35VN: Easier to sharpen than M390 thanks to its lower hardness and simpler carbide structure. It can be sharpened effectively with standard sharpening stones.
Wear Patterns
Wear patterns refer to how evenly a blade wears down over time:
- M390: Exhibits slow wear due to its extreme hardness but may develop micro-chips along the edge if used improperly.
- S35VN: Wears more evenly than M390 without developing chips as easily, making it ideal for tasks that involve repeated impact or rough use.
Practical Applications
Both steels are versatile but excel in different areas:
- M390:
- Best suited for applications requiring long-lasting sharpness such as professional kitchen knives or high-end EDC knives.
- Ideal for environments where corrosion resistance is critical (e.g., maritime settings).
- S35VN:
- Preferred for outdoor survival knives where toughness is essential.
- Suitable for users who value ease of sharpening over extreme edge retention.
Manufacturing Considerations
Production Method
Both steels are produced using powder metallurgy techniques:
- M390: Manufactured by Bohler-Uddeholm using advanced powder metallurgy that ensures uniform carbide distribution and minimal impurities[2].
- S35VN: Developed by Crucible Industries using similar powder metallurgy processes but with slightly simpler alloying elements[3].
Cost Implications
Due to the complexity of its composition and manufacturing process:
- M390 tends to be more expensive than S35VN by about 30%-50%, depending on the manufacturer[1][8].
This price difference makes S35VN a more cost-effective option for users who do not require the extreme performance characteristics of M390.
Direct Comparison Table
| Property | M390 | S35VN |
|---|---|---|
| Edge Retention | Excellent | Very Good |
| Toughness | Moderate | Excellent |
| Corrosion Resistance | Excellent | Very Good |
| Maximum Hardness | 60–62 HRC | 58–61 HRC |
| Ease of Sharpening | Difficult | Moderate |
| Cost Factor | High | Moderate |
Conclusion
Both M390 and S35VN are exceptional knife steels with distinct strengths:
- Choose M390 if you prioritize maximum edge retention and corrosion resistance at the expense of ease of sharpening.
- Opt for S35VN if you need a tougher steel that is easier to maintain while offering excellent overall performance at a lower cost.
For professional chefs or users who need extended cutting performance without frequent maintenance, M390 is the clear winner. However, for outdoor enthusiasts or those who value ease of sharpening alongside durability, S35VN may be the better choice.
Citations:
[1] https://damascussteelbillets.com/m390-vs-s35vn/
[2] https://nobliecustomknives.com/m390-steel/
[3] https://www.shieldon.net/s35vn-vs-m390-steel-which-one-is-better/
[4] https://www.reddit.com/r/knives/comments/ea15ow/s35vn_vs_m390/
[5] https://budgetlightforum.com/t/s35vn-m390/37463
[6] https://nobliecustomknives.com/elmax-steel/
[7] https://www.bladeforums.com/threads/s35vn-vs-m390.1538763/
[8] https://leeknives.com/s35vn-vs-m390/
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