CPM S90V and CPM 20CV represent two of the most advanced powder metallurgy steels available in the knife industry today. Both steels excel in edge retention and corrosion resistance, but they achieve their performance through different compositional approaches and offer distinct advantages for specific applications.
Chemical Composition and Microstructure
The fundamental differences between these steels lie in their chemical compositions:
| Element | CPM S90V | CPM 20CV |
|---|---|---|
| Carbon | 2.30% | 1.90% |
| Chromium | 14.00% | 20.00% |
| Vanadium | 9.00% | 4.00% |
| Molybdenum | 1.00% | 1.00% |
| Tungsten | 0% | 0.60% |
S90V features significantly higher vanadium content, which forms extremely hard vanadium carbides that contribute to exceptional wear resistance[1]. In contrast, 20CV achieves its performance through a higher chromium content, providing superior corrosion resistance while maintaining excellent wear characteristics[3].
Performance Metrics
Edge Retention
The CATRA (Cutlery and Allied Trade Research Association) testing reveals significant differences in edge retention capabilities:
- CPM S90V achieves approximately 220% better edge retention compared to 440C baseline[1]
- CPM 20CV scores 180% compared to the same baseline[7]
Corrosion Resistance
Laboratory testing shows relative corrosion rates in mm/year:
| Test Environment | CPM S90V | CPM 20CV |
|---|---|---|
| Boiling 10% Acetic | 9 | 12 |
| Dilute Aqua-Regia | 102 | 95 |
Both steels demonstrate exceptional corrosion resistance, with 20CV showing slightly better performance in aggressive environments due to its higher chromium content[3].
Hardness and Heat Treatment
Both steels can achieve high hardness levels through proper heat treatment:
CPM S90V:
- Austenitizing temperature: 2100-2150°F (1150-1175°C)
- Achievable hardness: 60-62 HRC[1]
CPM 20CV:
- Austenitizing temperature: 1950-2150°F (1066-1177°C)
- Achievable hardness: 59-61 HRC[2]
The heat treatment process is critical for both steels, requiring precise temperature control and multiple tempering cycles to achieve optimal properties[1][2].
Manufacturing Considerations and Cost Analysis
The powder metallurgy process used for both steels significantly impacts their production costs and final properties. Both S90V and 20CV are manufactured using Crucible’s CPM (Crucible Particle Metallurgy) process, which involves:
- Gas atomization of molten steel into fine powder
- Hot Isostatic Pressing (HIP)
- Traditional forging and rolling
Production Complexity
S90V presents greater manufacturing challenges due to:
- Higher carbide content requiring specialized grinding equipment
- More demanding heat treatment parameters
- Increased tool wear during machining
20CV offers somewhat easier manufacturability while maintaining excellent performance characteristics.
Cost Implications
The manufacturing costs directly affect retail pricing:
| Cost Factor | CPM S90V | CPM 20CV |
|---|---|---|
| Raw Material Cost | Very High | High |
| Processing Cost | Higher | High |
| Tool Wear Rate | Extreme | Moderate |
| Relative Price Index | 1.8 | 1.4 |
Real-World Performance Analysis
Edge Stability
- S90V demonstrates superior edge holding in high-wear applications
- 20CV provides better edge stability under impact
Sharpening Characteristics:
- S90V requires diamond abrasives and longer sharpening times
- 20CV responds well to conventional sharpening methods while maintaining good wear resistance
Wear Patterns
Long-term testing reveals distinct wear characteristics:
| Wear Type | CPM S90V | CPM 20CV |
|---|---|---|
| Abrasive Wear | Excellent | Very Good |
| Adhesive Wear | Good | Very Good |
| Chipping Resistance | Moderate | Good |
The high vanadium content in S90V creates extremely hard carbides that resist abrasive wear but can make the steel more susceptible to microchipping under certain conditions.
Practical Applications
CPM S90V Optimal Uses:
- High-end hunting knives
- Premium EDC blades
- Industrial cutting tools
- Applications requiring extreme edge retention
CPM 20CV Optimal Uses:
- Marine environments
- Food preparation
- Tactical knives
- General-purpose premium cutlery
Heat Treatment Optimization and Metallurgy
The heat treatment process significantly impacts the final properties of both steels. Here’s a detailed analysis of the optimal parameters:
CPM S90V Heat Treatment Protocol:
- Austenitizing temperature: 2100-2150°F (1150-1175°C)
- Hold time: 20 minutes
- Double tempering required at 400-750°F[3]
- Avoid tempering between 800-1000°F due to embrittlement risk[1]
CPM 20CV Heat Treatment Parameters:
- Preheating: 1400-1450°F (760-788°C)
- Austenitizing: 1960-2150°F (1071-1177°C)
- Lower temperatures maximize toughness
- Higher temperatures optimize wear and corrosion resistance[2]
Microstructural Characteristics
The CPM process creates distinct advantages for both steels:
S90V Microstructure:
- High volume of vanadium carbides
- Martensitic stainless steel matrix
- Vanadium carbides form preferentially over chromium carbides[1]
20CV Microstructure:
- Fine grain size
- Small, uniformly distributed carbides
- Superior cleanliness due to PM processing[2]
Comparative Performance Analysis
| Property | CPM S90V | CPM 20CV |
|---|---|---|
| CATRA Edge Retention | 220% | 180% |
| Impact Toughness | 19 ft-lb | 22 ft-lb |
| Corrosion Resistance | Superior | Exceptional |
| Carbide Formation | Vanadium-rich | Chromium-rich |
The high vanadium and 14% chromium in S90V results in very high wear resistance, leading to excellent performance in edge wear tests[5]. Meanwhile, 20CV achieves its performance through a unique combination of high chromium (20%) and moderate vanadium (4%) content[2].
Advanced Performance Testing and Analysis
Laboratory testing reveals specific performance characteristics that help understand the practical implications of each steel’s properties:
Wear Resistance Testing
Using the G65 Abrasion Test standard:
- S90V: Volume loss of 8.2 mm³
- 20CV: Volume loss of 12.4 mm³
These results demonstrate S90V’s superior wear resistance, primarily due to its vanadium carbide content.
Thermal Performance
Both steels exhibit different behaviors under thermal stress:
| Temperature Effect | CPM S90V | CPM 20CV |
|---|---|---|
| Tempering Response | Complex | Moderate |
| Red Hardness | Good | Very Good |
| Thermal Stability | Excellent | Good |
Frequently Asked Questions
Q: Which steel is better for everyday carry (EDC)?
A: 20CV offers a better balance for EDC use, combining excellent corrosion resistance with good edge retention and easier maintenance.
Q: Is the extra cost of S90V justified?
A: For applications requiring extreme edge retention and wear resistance, S90V’s premium price is justified. For general use, 20CV provides better value.
Q: How difficult is sharpening these steels?
A: S90V requires diamond abrasives and significant time investment. 20CV can be sharpened with conventional methods but still requires quality abrasives.
Q: How do they compare in rust resistance?
A: 20CV has slightly better corrosion resistance due to higher chromium content, though both perform excellently in corrosive environments.
Use Case Recommendations
Professional Use:
- S90V: Ideal for professional cutting tools where edge retention is paramount
- 20CV: Better suited for professional kitchen knives and marine applications
Recreational Use:
- S90V: Premium hunting and outdoor knives
- 20CV: High-end EDC and collection pieces
Economic Analysis and Market Position
The price-to-performance ratio reveals interesting insights for both steels:
| Economic Factor | CPM S90V | CPM 20CV |
|---|---|---|
| Market Position | Ultra-Premium | Premium |
| Cost Efficiency | Moderate | High |
| Availability | Limited | Good |
| Processing Cost | Very High | High |
Long-term Value Proposition
CPM S90V Benefits:
- Exceptional edge retention reduces maintenance frequency
- Premium market positioning
- Unique performance characteristics
CPM 20CV Advantages:
- Better balance of properties
- More widespread availability
- Lower maintenance costs
Final Recommendations
Choose S90V when:
- Maximum edge retention is the primary requirement
- Budget is not a primary concern
- Professional sharpening services are available
Choose 20CV when:
- Balanced performance is desired
- Corrosion resistance is crucial
- Self-maintenance is planned
- Cost-effectiveness is important
This concludes the complete technical comparison between CPM S90V and CPM 20CV steels. The analysis provides a thorough understanding of their properties, performance characteristics, and optimal applications, helping users make informed decisions based on their specific needs and requirements.
Citations:
[1] https://www.alphaknifesupply.com/Pictures/Info/Steel/CPMS90-DS.pdf
[2] https://www.alphaknifesupply.com/Pictures/Info/Steel/20CV-DS.pdf
[3] https://www.alphaknifesupply.com/Pictures/Info/Steel/CPM20CV-DS.pdf
[4] https://www.nozeakatany.cz/en/cpm-20cv/
[5] https://www.wolframalpha.com/input?input=20CV+steel+edge+retention+rating
[6] https://knifesteelnerds.com/2020/05/01/testing-the-edge-retention-of-48-knife-steels/
[7] https://knifeup.com/how-good-is-cpm-20cv-knife-steel/
[8] https://nobliecustomknives.com/cpm-20cv/
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