When it comes to high-performance knife steels, S90V and S35VN are two of the most popular choices among knife enthusiasts, hunters, and outdoor professionals. Both steels are produced using Crucible’s CPM (Crucible Particle Metallurgy) process, which ensures a fine, homogenous microstructure with excellent properties.
However, despite their shared pedigree, these two steels offer significantly different performance characteristics in terms of edge retention, toughness, corrosion resistance, and ease of sharpening.
In this article, we will compare S90V and S35VN across several key parameters using scientific data and measurable properties. We will analyze their chemical compositions, performance metrics like edge retention and toughness, heat treatment requirements, and real-world performance. By the end of this comparison, you will have a clear understanding of which steel is better suited for specific applications.
Composition Analysis
The chemical composition of a steel alloy determines its hardness, toughness, wear resistance, and corrosion resistance. Both S90V and S35VN are stainless steels with high chromium content but differ significantly in other alloying elements.
| Element | S90V (%) | S35VN (%) |
|---|---|---|
| Carbon (C) | 2.30 | 1.40 |
| Chromium (Cr) | 14.00 | 14.00 |
| Vanadium (V) | 9.00 | 3.00 |
| Molybdenum (Mo) | 1.00 | 2.00 |
| Niobium (Nb) | – | 0.50 |
| Manganese (Mn) | 0.50 | 0.50 |
| Silicon (Si) | 0.50 | 0.50 |
Key Alloying Elements:
- Carbon (C): Carbon increases hardness and wear resistance by forming carbides with other elements like vanadium or chromium. S90V has a much higher carbon content (2.30%) compared to S35VN (1.40%), which contributes to its superior wear resistance but also makes it more brittle.
- Vanadium (V): Vanadium forms extremely hard vanadium carbides that enhance wear resistance and edge retention. S90V contains a whopping 9% vanadium compared to just 3% in S35VN, making it one of the best steels for edge retention.
- Niobium (Nb): Unique to S35VN, niobium helps improve toughness without sacrificing wear resistance or hardness.
- Molybdenum (Mo): Molybdenum enhances corrosion resistance and toughness. While both steels contain molybdenum, S35VN has twice the amount found in S90V.
Performance Metrics
Edge Retention
Edge retention is often measured using the CATRA test, which simulates cutting abrasive material to evaluate how long a blade stays sharp.
- S90V: Known for exceptional edge retention due to its high vanadium carbide content (~9%), S90V performs at the top tier in CATRA tests with results often exceeding steels like M390 or ZDP-189[1][2]. It can retain a sharp edge for extended periods even under heavy use.
- S35VN: While not as impressive as S90V in terms of edge retention, S35VN still performs well due to its balanced composition of vanadium and niobium carbides[3]. In CATRA tests, it holds an edge longer than many mainstream steels but falls short of ultra-premium options like S90V.
Toughness
Toughness is crucial for resisting chipping or breaking under impact or stress.
- S90V: Due to its high carbide volume (~17%), S90V sacrifices some toughness compared to other steels[2]. It is more prone to chipping when subjected to lateral forces or impacts.
- S35VN: Designed as an improvement over its predecessor S30V, S35VN has better toughness due to the addition of niobium carbides[3]. It is less likely to chip or fracture under impact, making it a more forgiving steel for heavy-duty tasks like chopping or batoning.
Corrosion Resistance
Both steels are classified as stainless due to their high chromium content (>10%), which provides good resistance to rust and corrosion.
- S90V: With 14% chromium and additional molybdenum, S90V offers excellent corrosion resistance[1]. However, due to its high carbon content and large carbide volume, it may not perform as well as some other stainless steels in highly corrosive environments.
- S35VN: Also containing 14% chromium but with lower carbon content and more molybdenum than S90V, S35VN offers slightly better corrosion resistance[3]. It is well-suited for use in humid or marine environments where rust is a concern.
Hardness Range
Hardness is typically measured on the Rockwell C scale (HRC), with higher values indicating harder steel.
- S90V: Typically hardened between 58-61 HRC, depending on the heat treatment[1][2]. This high hardness contributes to its excellent wear resistance but makes it more brittle.
- S35VN: Typically hardened between 57-59 HRC, making it slightly softer than S90V[3]. This lower hardness improves toughness while still providing good wear resistance.
Heat Treatment Considerations
Heat treatment plays a critical role in optimizing the performance of both steels by balancing hardness, toughness, and wear resistance.
Optimal Heat Treatment Parameters:
- S90V
- Austenitizing Temperature: ~2050°F
- Quenching: Oil or plate quenching
- Tempering Temperature: ~400°F for maximum hardness (~60 HRC)[2]
- S35VN
- Austenitizing Temperature: ~1950°F
- Quenching: Oil or air quenching
- Tempering Temperature: ~400°F for maximum hardness (~58 HRC)[3]
Real-World Performance
Edge Stability
Edge stability refers to how well a steel maintains its sharpness without deforming or chipping during use.
- S90V: Thanks to its high vanadium carbide content, S90V excels at maintaining a fine edge over time[1][2]. However, if subjected to lateral stresses such as twisting cuts or prying motions, it can be prone to chipping due to its brittleness.
- S35VN: With better overall toughness than S90V, S35VN offers superior edge stability when used in tasks that involve impact or lateral forces[3]. It is less likely to chip under heavy use but may dull faster than S90V when cutting abrasive materials.
Sharpening Behavior
One of the most commonly discussed drawbacks of high-performance steels is their difficulty in sharpening.
- S90V: Due to the large volume of hard vanadium carbides (~9%), sharpening S90V can be challenging without diamond abrasives[1][6]. However, once sharpened properly, it holds an edge for an exceptionally long time.
- S35VN: Easier to sharpen than S90V due to its lower carbide volume (~3% vanadium)[3], making it more user-friendly for those who prefer traditional sharpening stones or ceramic rods.
Wear Patterns
Wear patterns develop over time as a knife blade is used repeatedly for cutting tasks.
- S90V: Exhibits minimal wear over time thanks to its extreme wear resistance[1][2]. Even after prolonged use on tough materials like rope or cardboard, an S90V blade will show little sign of dulling.
- S35VN: While not as resistant as S90V when cutting abrasive materials[5], S35VN still offers good wear resistance for most everyday tasks like food preparation or wood carving.
Manufacturing Considerations
Both steels are produced using Crucible’s CPM process—a form of powder metallurgy that results in fine grain structures with uniform distribution of carbides.
Production Costs:
The CPM process itself adds significant cost compared to conventional steel manufacturing methods due to the complexity involved in producing fine powders from molten metal before compacting them into solid bars[4].
- S90V: More expensive than many other knife steels due primarily to its high vanadium content and complex manufacturing process[4].
- S35VN: Slightly less expensive than S90V because it contains fewer expensive alloying elements like vanadium[5].
Conclusion
In conclusion:
- If you prioritize edge retention above all else—such as for tasks involving repetitive cutting on abrasive materials—then S90V is one of the best choices available today.
- For users who need toughness and ease of sharpening—such as those using knives for outdoor activities like camping or hunting—then S35VN offers better all-around performance with fewer trade-offs in terms of durability under stress.
Both steels are excellent choices depending on your specific needs:
| Property | CPM-S90V | CPM-S35VN |
|---|---|---|
| Edge Retention | Superior | Good |
| Toughness | Moderate | Excellent |
| Corrosion Resistance | Good | Very Good |
| Hardness Range | 58–61 HRC | 57–59 HRC |
| Sharpening Ease | Difficult | Moderate |
Citations:
[1] https://blog.hdmdknives.com/s90v-steel.html
[2] https://knifesteelnerds.com/2020/09/28/s90v-and-s125v-knife-steel-history-properties-and-how-to-heat-treat/
[3] https://www.tuofa-cncmachining.com/tuofa-blog/s35vn-steel.html
[4] https://forum.spyderco.com/viewtopic.php?t=94034
[5] https://www.shieldon.net/s35vn-vs-m390-steel-which-one-is-better/
[6] https://forum.spyderco.com/viewtopic.php?t=92560
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