The world of high-performance knife steels presents a fascinating comparison between Maxamet and CPM-S90V, two super steels that represent different approaches to achieving premium cutting performance. Both steels showcase advanced metallurgy, but they achieve their remarkable properties through distinct compositions and manufacturing methods.
Chemical Composition and Structure
| Element | Maxamet | CPM-S90V |
|---|---|---|
| Carbon | 2.15% | 2.30% |
| Chromium | 4.75% | 14.00% |
| Vanadium | 6.00% | 9.00% |
| Tungsten | 13.00% | 0.40% |
| Cobalt | 10.00% | – |
| Molybdenum | – | 1.00% |
| Silicon | 0.25% | 0.50% |
| Manganese | 0.30% | 0.50% |
Key Compositional Differences
Maxamet’s composition focuses on extreme hardness through its unique combination of high tungsten and cobalt content[1][2]. The steel achieves remarkable edge retention through its 6% vanadium content and forms complex carbides with its 13% tungsten content. In contrast, S90V emphasizes a balance of properties with its higher chromium content for corrosion resistance and an impressive 9% vanadium for wear resistance[4].
Performance Characteristics
Hardness and Edge Retention
Maxamet demonstrates exceptional hardness, reaching 67-69 HRC on the Rockwell scale[1]. This extreme hardness contributes to its superior edge retention, with CATRA test results showing approximately 2.2 times the edge retention of 440C at 59 HRC[3]. S90V, while not reaching Maxamet’s extreme hardness levels, still maintains excellent edge retention due to its high vanadium carbide content[4].
Corrosion Resistance
The corrosion resistance comparison heavily favors S90V. With its 14% chromium content, S90V qualifies as a true stainless steel, offering superior resistance to rust and corrosion[4]. Maxamet, with only 4.75% chromium, provides satisfactory corrosion resistance but requires more careful maintenance to prevent oxidation[1].
Carbide Structure
Maxamet’s microstructure contains approximately 22% carbide volume, contributing to its wear resistance while maintaining reasonable toughness[3]. The powder metallurgy process used in its manufacture ensures a fine, uniform carbide distribution. S90V also features a complex carbide structure, with its high vanadium content forming extremely hard vanadium carbides that contribute to wear resistance[4].
Manufacturing Processes and Production Challenges
Powder Metallurgy Excellence
Both Maxamet and S90V are produced through advanced powder metallurgy (PM) processes, which ensures superior homogeneity and refined grain structure. The PM process involves atomizing molten steel into fine particles, which are then consolidated under high pressure and temperature. This method is particularly crucial for these steels due to their high alloy content, which would cause significant segregation issues in conventional casting.
Cost Implications
The manufacturing cost differential between these steels is significant:
| Cost Factor | Maxamet | S90V |
|---|---|---|
| Raw Material Cost | Very High | High |
| Processing Complexity | Extreme | High |
| Equipment Wear | Severe | Moderate |
| Production Yield | 85-90% | 90-95% |
| Relative Cost Index | 180-200 | 140-160 |
Heat Treatment Specifications
Critical Parameters
Maxamet’s heat treatment requires precise control:
- Preheating: 1500°F (815°C)
- Austenitizing: 2150°F (1175°C)
- Quenching: Vacuum or high-pressure gas
- Triple tempering: 1025°F (552°C)
S90V’s heat treatment protocol:
- Preheating: 1400°F (760°C)
- Austenitizing: 2100°F (1149°C)
- Quenching: Vacuum or oil
- Double tempering: 1000°F (538°C)
Thermal Processing Challenges
Maxamet presents unique challenges during heat treatment due to its high alloy content. The steel requires precise temperature control to avoid decarburization and maintain optimal carbide distribution. The triple tempering cycle is essential for stress relief and achieving the desired combination of hardness and toughness.
Real-World Performance Analysis
Edge Stability
Maxamet exhibits exceptional edge stability under high-stress cutting tasks. The steel’s high tungsten content creates stable carbides that resist deformation even under significant lateral forces. Edge retention testing shows:
| Test Type | Maxamet | S90V |
|---|---|---|
| CATRA (relative) | 310 | 245 |
| Edge Stability | Excellent | Very Good |
| Micro-chipping Resistance | Moderate | Good |
Sharpening Characteristics
Both steels present challenges during sharpening:
Maxamet:
- Requires diamond abrasives
- Longer sharpening time
- Benefits from progression through multiple grits
- Final edge extremely stable
S90V:
- Responds well to ceramic stones
- Moderate sharpening difficulty
- Good response to stropping
- Maintains working edge longer
Practical Applications and Performance Analysis
Industrial Performance Data
Maxamet has demonstrated exceptional durability in industrial applications. In one documented case, a Maxamet roll showed only 0.003″ wear after processing 320,000 feet of material[1]. This extraordinary wear resistance translates directly to knife applications, where edge retention is paramount.
Wear Patterns and Edge Stability
| Performance Metric | Maxamet | S90V |
|---|---|---|
| Industrial Wear Rate | 0.003″/320k ft | Not Available |
| Carbide Volume | ~22% | ~15% |
| Edge Stability at HRC | 68-70 HRC | 60-62 HRC |
| Relative Wear Resistance | Superior | Very Good |
Comparative Edge Retention
Recent testing has shown that Maxamet’s edge retention surpasses that of Z-Max/Rex 86, primarily due to its higher vanadium content (6% vs 5%)[2]. The steel maintains its performance advantage even at extreme hardness levels, though toughness becomes a consideration at hardness levels above 68 HRC.
Application-Specific Recommendations
Best Use Cases for Maxamet:
- Precision cutting tools requiring extreme edge retention
- Industrial applications where minimal maintenance is desired
- High-performance EDC knives for experienced users
- Applications where maximum hardness is prioritized over toughness
Best Use Cases for S90V:
- Marine environments requiring corrosion resistance
- General-purpose high-end cutlery
- Applications requiring balance between wear resistance and toughness
- Situations where easier maintenance is preferred
Frequently Asked Questions
Q: Is Maxamet worth the premium price over S90V?
A: For users prioritizing absolute maximum edge retention and wear resistance, Maxamet justifies its premium. However, S90V offers better corrosion resistance and easier maintenance for general use.
Q: What’s the main difference in sharpening requirements?
A: While both steels are challenging to sharpen, Maxamet typically requires diamond abrasives for optimal results. S90V can be effectively sharpened with ceramic stones, though diamond abrasives are recommended[3].
Q: How does the hardness affect practical use?
A: Maxamet’s extreme hardness (67-69 HRC) provides superior edge retention but requires more careful use to prevent chipping. S90V’s moderate hardness (60-62 HRC) offers better impact resistance[2].
Q: Which steel requires more maintenance?
A: Maxamet requires more careful maintenance due to lower corrosion resistance. S90V, with its higher chromium content, offers better corrosion resistance and requires less frequent maintenance.
Citations:
[1] https://bladeops.com/blog/knife-steel-maxamet-steel/
[2] https://www.spydiewiki.com/index.php/Maxamet
[3] https://knifesteelnerds.com/2019/12/02/super-hard-70-rc-high-speed-steels-maxamet-rex-121-and-more-explained/
[4] https://blog.hdmdknives.com/s90v-steel.html
[5] https://knifesteelnerds.com/2021/10/19/knife-steels-rated-by-a-metallurgist-toughness-edge-retention-and-corrosion-resistance/
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