The evolution of high-performance knife steels has led to remarkable advancements, with CPM S90V and S110V representing the pinnacle of wear-resistant stainless steels. Both developed by Crucible Industries, these steels offer exceptional edge retention and corrosion resistance, though with distinct characteristics that set them apart.
Chemical Composition and Structure
| Element | CPM S90V | CPM S110V |
|---|---|---|
| Carbon | 2.30% | 2.80% |
| Chromium | 14.00% | 15.25% |
| Vanadium | 9.00% | 9.00% |
| Molybdenum | 1.00% | 2.25% |
| Niobium | – | 3.00% |
| Cobalt | – | 2.50% |
The key distinction lies in S110V’s addition of niobium and increased chromium content[4]. This modification results in approximately 25% greater volume of wear-resistant carbides, with 50% more of the highly desirable MC-type carbides[4]. The higher chromium content in S110V provides enhanced corrosion resistance compared to S90V[1].
Carbide Formation and Microstructure
S90V’s high vanadium content promotes the formation of hard vanadium carbides instead of chromium carbides, leaving more free chromium for corrosion resistance[1]. S110V builds upon this foundation with its niobium addition, which creates an even finer carbide structure:
- S90V: ~21% carbide volume
- S110V: ~27% carbide volume[5]
The niobium in S110V contributes to a finer overall carbide structure, which is remarkable given its higher total carbide volume[5]. This refinement in microstructure impacts several performance characteristics:
- Better edge stability
- Improved toughness despite higher carbide content
- Enhanced corrosion resistance due to more free chromium[5]
Performance Metrics
Edge Retention
S90V demonstrates superior edge retention compared to most commercial steels, while S110V pushes these boundaries even further[2]. In CATRA testing, both steels consistently rank among the highest performers, with S90V showing slightly better results in some cases[8].
Corrosion Resistance
| Steel | Relative Rating (1-10) |
|---|---|
| S90V | 5 |
| S110V | 6 |
| 440C | 4 |
S110V exhibits better corrosion resistance due to:
- Higher chromium content (15.25% vs 14.00%)
- More efficient carbide formation leaving additional free chromium
- Enhanced molybdenum content[5]
Heat Treatment Parameters and Optimization
The heat treatment process significantly impacts the performance of both steels, with specific requirements for optimal results:
S90V Heat Treatment
- Austenitizing temperature: 2050°F (1120°C)
- Double tempering required at 400-750°F (200-400°C)
- Minimum 2 hours per temper cycle[1]
- Freezing treatment may be necessary between tempers to minimize retained austenite
- Optimal hardness range: HRC 56-59[1]
S110V Heat Treatment
- Higher austenitizing temperature: 2150°F (1175°C)
- Triple tempering required with complete cooling between cycles
- Tempering options:
- 400-750°F (200-400°C) for maximum corrosion resistance
- 975-1000°F (525-540°C) for peak hardness
- 1025-1050°F (550-565°C) for stress relief[2]
Manufacturing Considerations
Both steels are produced through Crucible’s Particle Metallurgy (CPM) process, which results in several manufacturing implications:
Machinability and Grinding
- S110V exhibits slightly more challenging machining characteristics compared to S90V
- Both require specialized grinding equipment:
- SG type alumina wheels recommended
- CBN wheels provide optimal performance[2]
- Higher wear on tooling during manufacturing
- Increased production costs due to:
- Extended machining time
- More frequent tool replacement
- Higher energy requirements for heat treatment
Size Changes During Heat Treatment
Both steels experience similar dimensional changes:
- +0.03 to +0.05% size increase for fully martensitic structure
- Retained austenite may reduce net growth[1][2]
Real-World Performance
Edge Stability
Surprisingly, testing has shown that S90V can outperform S110V in certain edge retention tests, despite S110V’s higher alloy content[3]. This unexpected result may be attributed to:
- Carbide size and distribution differences
- Optimal balance of vanadium carbides in S90V
- More efficient chromium utilization in S90V’s matrix
Wear Resistance Comparison
| Property | S90V | S110V |
|---|---|---|
| Total Carbide Volume | 21% | 27% |
| MC-type Carbides | Base | +50% |
| Relative Wear Rating | 35/40 | 40/45 |
Practical Applications and Use Cases
Kitchen Cutlery
S90V demonstrates better characteristics for culinary applications due to:
- Superior edge stability in protein-rich environments
- Better resistance to acidic food reactions
- More predictable sharpening behavior
- Lower tendency for microchipping during board contact
Outdoor and Hunting Applications
S110V excels in demanding outdoor scenarios:
- Extended field use without maintenance
- Superior wear resistance in abrasive environments
- Enhanced resistance to natural elements
- Better performance in high-humidity conditions
Sharpening Characteristics and Maintenance
S90V Sharpening Profile
- Requires diamond or CBN abrasives
- Recommended progression:
- Initial bevel setting: 100-200 grit
- Refinement: 400-600 grit
- Final edge: 800-1200 grit
- Average sharpening time: 15-20 minutes for full progression
S110V Sharpening Profile
- Demands premium diamond stones
- Extended sharpening sequence:
- Initial bevel: 100-200 grit
- Multiple intermediate steps required
- Final polish: 1200-1500 grit
- Average sharpening time: 25-30 minutes for full progression
Cost-Benefit Analysis
| Factor | S90V | S110V |
|---|---|---|
| Raw Material Cost | $$$$ | $$$$$ |
| Processing Cost | High | Very High |
| Edge Longevity | Excellent | Superior |
| Maintenance Cost | High | Very High |
| Overall Value | Better for most users | Specialized applications |
Frequently Asked Questions
Q: Which steel holds an edge longer?
A: While S110V technically has higher wear resistance, real-world testing shows comparable edge retention between both steels, with S90V sometimes performing better in specific applications.
Q: Is the extra cost of S110V justified?
A: For most users, S90V provides the better value proposition. S110V’s advantages become apparent only in specialized applications requiring extreme wear resistance.
Q: Can these steels be sharpened without professional equipment?
A: Both steels require high-quality diamond stones for effective sharpening. Professional equipment is recommended but not mandatory for maintaining a working edge.
Q: How does corrosion resistance compare to conventional steels?
A: Both significantly outperform conventional stainless steels, with S110V having a slight edge due to higher chromium content and more efficient carbide formation.
Conclusion and Recommendations
The choice between S90V and S110V should be based on specific use cases:
Choose S90V for:
- General high-performance applications
- Better value proposition
- Easier maintenance
- Kitchen and food preparation
- Better balance of properties
Choose S110V for:
- Extreme wear resistance requirements
- Professional outdoor applications
- Applications where maintenance intervals must be maximized
- Situations requiring maximum corrosion resistance
Citations:
[1] https://www.crucible.com/eselector/prodbyapp/plastics/s90vp.html
[2] https://tassietigerknives.com.au/steel-types/
[3] https://knifesteelnerds.com/2021/10/19/knife-steels-rated-by-a-metallurgist-toughness-edge-retention-and-corrosion-resistance/
[4] https://www.crucible.com/PDFs/DataSheets2010/Datasheet%20CPM%20S110Vv12010.pdf
[5] https://knifesteelnerds.com/2020/11/23/cpm-s110v-steel-history-and-properties/
[6] https://knifeup.com/cpm-s110v-steel/
[7] https://www.linkedin.com/pulse/cpm-s90v-steel-heat-treatment-hrc-60-62-cy-tan
[8] https://knifesteelnerds.com/2020/09/28/s90v-and-s125v-knife-steel-history-properties-and-how-to-heat-treat/
[9] https://knifeinformer.com/discovering-the-best-knife-steel/
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