M390 and Elmax are two of the most highly regarded steels in the knife-making industry, both produced through advanced powder metallurgy processes. These steels are known for their exceptional balance of wear resistance, edge retention, and corrosion resistance. M390, developed by Böhler-Uddeholm, is often praised for its superior edge retention and corrosion resistance, while Elmax, produced by Uddeholm, is recognized for its toughness and ease of sharpening.
In this article, we will delve into a detailed comparison of M390 and Elmax based on scientific data and measurable properties. We will explore their chemical compositions, performance metrics such as edge retention and toughness, heat treatment requirements, and real-world performance characteristics. By the end of this comparison, you will have a clear understanding of which steel is better suited for your specific needs.
Composition Analysis
The chemical composition of a steel plays a critical role in determining its properties such as hardness, toughness, wear resistance, and corrosion resistance. Below is a comparison of the key alloying elements in M390 and Elmax:
| Element | M390 (%) | Elmax (%) |
|---|---|---|
| Carbon (C) | 1.90 | 1.70 |
| Chromium (Cr) | 20.00 | 18.00 |
| Vanadium (V) | 4.00 | 3.00 |
| Molybdenum (Mo) | 1.00 | 1.00 |
| Tungsten (W) | 0.60 | – |
| Silicon (Si) | 0.70 | 0.80 |
| Manganese (Mn) | 0.30 | 0.30 |
Both steels are high-carbon stainless steels with substantial amounts of chromium for corrosion resistance and vanadium for wear resistance and toughness.
Key Alloying Elements:
- Carbon (C): Contributes to hardness and edge retention.
- Chromium (Cr): Enhances corrosion resistance.
- Vanadium (V): Improves wear resistance by forming hard vanadium carbides.
- Molybdenum (Mo): Increases strength at high temperatures and enhances corrosion resistance.
- Tungsten (W): Found only in M390, tungsten improves wear resistance by forming hard carbides.
Performance Metrics
Edge Retention
Edge retention is one of the most important factors for knife users, especially in applications where frequent sharpening is impractical.
- M390: Scored 958.6 on the CATRA TCC test[5], indicating excellent edge retention due to its high carbide volume.
- Elmax: Scored 930.7 on the same test[5], which is slightly lower than M390 but still very impressive.
Toughness
Toughness refers to a steel’s ability to resist chipping or breaking under impact.
- M390: Known for its high hardness but slightly lower toughness compared to Elmax[3]. This makes it more prone to chipping under heavy use.
- Elmax: Offers better toughness than M390 due to its balanced composition[3]. It can withstand more impact without chipping, making it ideal for heavy-duty applications.
Corrosion Resistance
Both steels are highly resistant to corrosion due to their high chromium content.
- M390: With 20% chromium, M390 has superior corrosion resistance compared to most other stainless steels[2].
- Elmax: While also highly resistant to corrosion with 18% chromium, it falls slightly behind M390 in this category[3].
Hardness Range
Hardness is measured on the Rockwell C scale (HRC), which indicates how resistant the material is to deformation.
- M390: Typically hardened between 60–62 HRC, with some custom treatments reaching up to 64 HRC[1][5].
- Elmax: Generally hardened between 57–59 HRC, but can be pushed up to 62 HRC under optimal conditions[5].
Heat Treatment Considerations
The heat treatment process is crucial for optimizing the performance of both M390 and Elmax steels.
M390 Heat Treatment
M390 requires a precise heat treatment protocol due to its complex carbide structure:
- Austenitizing Temperature: Typically around 2150°F (1177°C)[2].
- Tempering Temperature: Can vary between 350°F–570°F (177°C–299°C) depending on desired hardness[1].
- Cryogenic Treatment: Deep freezing at sub-zero temperatures is often used to enhance hardness and wear resistance by transforming retained austenite into martensite[2].
The complexity of heat treating M390 makes it more challenging for manufacturers but results in superior performance when done correctly.
Elmax Heat Treatment
Elmax is easier to heat treat compared to M390:
- Austenitizing Temperature: Around 2100°F (1149°C)[3].
- Tempering Temperature: Typically between 400°F–600°F (204°C–316°C)[3].
- Cryogenic Treatment: While not always necessary, cryo treatment can improve hardness and dimensional stability[5].
Due to its simpler heat treatment process, Elmax is often preferred by custom knife makers who want consistent results without the need for highly specialized equipment.
Real-World Performance
Edge Stability
Edge stability refers to how well a knife retains its sharpness under stress without deforming or chipping.
- M390: Offers excellent edge stability due to its high hardness and fine carbide distribution[2]. However, it can be more prone to chipping if subjected to heavy impact or lateral forces.
- Elmax: Provides better overall edge stability in tougher conditions due to its higher toughness rating[3]. It’s less likely to chip under heavy use but may dull slightly faster than M390.
Sharpening Behavior
Both steels are relatively difficult to sharpen due to their high hardness levels.
- M390: More challenging to sharpen because of its extreme wear resistance and harder carbides[2]. However, once sharpened, it holds an edge exceptionally well.
- Elmax: Easier to sharpen than M390 while still maintaining good wear resistance[5]. This makes it a better choice for users who prefer ease of maintenance over maximum edge retention.
Wear Patterns
Wear patterns refer to how evenly or unevenly a blade wears down over time with use.
- M390: Exhibits very slow wear due to its high volume of vanadium and chromium carbides[2]. This makes it ideal for applications where long-term durability is essential.
- Elmax: Wears slightly faster than M390 but still offers excellent durability thanks to its balanced composition of carbides[5].
Manufacturing Considerations
Both M390 and Elmax are produced using powder metallurgy technology, which results in superior structural uniformity compared to traditional steel-making methods.
Production Method
- Both steels undergo atomization followed by pressing and sintering processes that result in fine-grained microstructures with uniform carbide distribution[3][4].
Cost Implications
- M390: More expensive due to its higher alloy content and more complex manufacturing process[2]. The cost also reflects the difficulty in grinding and finishing blades made from this steel.
- Elmax: Slightly less expensive than M390 but still considered a premium steel due to its performance characteristics and powder metallurgy production process[5].
Direct Comparison Table
| Property | M390 | Elmax |
|---|---|---|
| Edge Retention | Very High | High |
| Toughness | Moderate | High |
| Corrosion Resistance | Very High | High |
| Maximum Hardness | Up to 64 HRC | Up to 62 HRC |
| Sharpening Difficulty | Difficult | Moderate |
| Cost Factor | High | Moderate |
Real-World Performance (Continued)
Practical Applications and Limitations
Both M390 and Elmax are versatile steels that can be used in a wide range of applications, but their specific properties make them more suitable for certain tasks. Let’s take a closer look at where each steel excels and where it may fall short.
M390 Applications
M390 is often considered a “super steel” due to its exceptional edge retention, corrosion resistance, and wear resistance. These properties make it ideal for applications where long-term durability is essential, such as:
- High-End EDC (Everyday Carry) Knives: M390 is a popular choice for premium EDC knives because users want a blade that stays sharp for extended periods without frequent sharpening.
- Outdoor and Survival Knives: The combination of excellent corrosion resistance and edge retention makes M390 well-suited for outdoor environments where moisture and harsh conditions are common.
- Tactical Knives: M390’s ability to hold an edge under demanding conditions makes it a top choice for tactical or combat knives, where reliability is critical.
Limitations:
- Chipping Risk: While M390 has excellent hardness and edge retention, its toughness is lower than Elmax. This makes it more prone to chipping if subjected to heavy impacts or lateral forces.
- Sharpening Difficulty: The high hardness and carbide content make M390 more difficult to sharpen, especially for users without advanced sharpening tools.
Elmax Applications
Elmax offers a more balanced performance profile with higher toughness and slightly easier sharpening compared to M390. This makes it an excellent choice for:
- Heavy-Duty Outdoor Knives: Elmax’s superior toughness makes it ideal for chopping, batoning, or other heavy-duty tasks where the blade may encounter impacts or lateral stresses.
- Kitchen Knives: The combination of good corrosion resistance, ease of sharpening, and toughness makes Elmax a strong contender for high-quality kitchen knives that need to be durable yet easy to maintain.
- Hunting Knives: Elmax’s toughness allows it to handle skinning and field dressing tasks without chipping, while its corrosion resistance ensures longevity in wet or humid environments.
Limitations:
- Slightly Lower Edge Retention: While Elmax has good edge retention, it doesn’t quite match the performance of M390 in this regard. Users who prioritize maximum edge retention may prefer M390.
- Corrosion Resistance: Although highly resistant to corrosion, Elmax falls slightly behind M390 in this category due to its lower chromium content.
Sharpening Behavior
Sharpening behavior is a key consideration for knife users, especially those who frequently maintain their blades. Both M390 and Elmax are challenging to sharpen compared to simpler steels like 1095 or AUS-8, but there are some differences between the two.
M390 Sharpening
M390’s high vanadium content (4%) results in the formation of vanadium carbides, which are extremely hard. This gives the steel its excellent wear resistance but also makes sharpening more difficult. Users will need high-quality diamond or ceramic stones to efficiently sharpen an M390 blade.
Key Points:
- Difficulty Level: High. Diamond stones are recommended.
- Edge Retention After Sharpening: Once sharpened properly, M390 holds an edge exceptionally well due to its high hardness and carbide structure.
- Time Required: Sharpening can take longer due to the hardness of the carbides.
Elmax Sharpening
Elmax contains less vanadium (3%) than M390, which means fewer vanadium carbides are present in the steel. This makes Elmax somewhat easier to sharpen than M390 while still offering good wear resistance. It can be sharpened with high-quality water stones or ceramic stones without as much difficulty as M390.
Key Points:
- Difficulty Level: Moderate. Water stones or ceramic stones work well.
- Edge Retention After Sharpening: While not as long-lasting as M390’s edge, Elmax still holds a sharp edge for extended periods.
- Time Required: Sharpening takes less time compared to M390 due to the lower carbide volume.
Wear Patterns
Wear patterns tell us how evenly or unevenly a blade wears down over time with use. Both steels have unique wear characteristics due to their carbide structures.
M390 Wear Patterns
M390’s wear pattern is characterized by slow and even wear over time. Its high volume of vanadium carbides contributes to exceptional wear resistance, meaning that the blade will maintain its cutting performance for longer periods before showing signs of dullness.
Key Points:
- Wear Rate: Very slow due to high carbide volume.
- Evenness of Wear: Uniform; doesn’t develop uneven spots easily.
Elmax Wear Patterns
Elmax also exhibits good wear resistance but tends to wear down slightly faster than M390 due to its lower carbide content. However, its balanced composition allows it to maintain a relatively even wear pattern without developing significant weak spots.
Key Points:
- Wear Rate: Moderate; wears faster than M390 but still offers good durability.
- Evenness of Wear: Uniform; maintains consistent cutting performance over time.
Manufacturing Considerations
The production methods used for both M390 and Elmax involve powder metallurgy (PM) technology. PM steels are known for their fine-grained microstructures and uniform carbide distribution, which result in superior performance compared to conventionally produced steels.
Production Method
Both steels are produced using similar powder metallurgy processes:
- Atomization Process: Molten steel is atomized into fine powder particles.
- Pressing & Sintering: The powder is pressed into billets and sintered at high temperatures.
- Hot Isostatic Pressing (HIP): The billets undergo HIP treatment to remove any porosity and achieve full density.
The result is a fine-grained microstructure with uniformly distributed carbides, which enhances both wear resistance and toughness.
Cost Analysis
Both M390 and Elmax are premium steels that come at a higher price point compared to simpler stainless steels like 440C or AUS-8. However, there are some differences in cost between the two:
- M390 Cost: Generally more expensive due to its higher alloy content (particularly vanadium) and more complex manufacturing process. The cost also reflects the difficulty in grinding and finishing blades made from this steel.
- Elmax Cost: Slightly less expensive than M390 but still considered a premium steel due to its performance characteristics and powder metallurgy production process.
For manufacturers, working with either steel requires specialized equipment due to their hardness levels. However, Elmax is generally easier to machine and finish compared to M390 because of its lower carbide volume.
Conclusion
Both M390 and Elmax are top-tier knife steels that offer excellent performance across various metrics, but they excel in different areas:
- M390 stands out with its superior edge retention and corrosion resistance, making it ideal for applications where long-term sharpness and durability are crucial. However, it comes at the cost of reduced toughness and increased difficulty in sharpening.
- Elmax, on the other hand, offers better toughness while still maintaining good edge retention and corrosion resistance. It’s easier to sharpen than M390, making it a great choice for users who value ease of maintenance along with durability.
Best Use Cases
| Steel | Best For | Not Ideal For |
|---|---|---|
| M390 | High-end EDC knives, outdoor survival knives | Heavy-duty impact tasks |
| Elmax | Heavy-duty outdoor knives, kitchen knives | Maximum edge retention applications |
Final Recommendation
If you prioritize maximum edge retention and corrosion resistance over ease of sharpening or toughness, then M390 is likely the better choice for you. On the other hand, if you need a tough steel that can handle heavy-duty tasks while still being relatively easy to maintain, then Elmax would be more suitable.
Frequently Asked Questions (FAQ)
- Which steel holds an edge longer?
- M390 holds an edge longer than Elmax due to its higher volume of hard carbides.
- Is Elmax easier to sharpen than M390?
- Yes, Elmax is easier to sharpen because it has fewer hard carbides compared to M390.
- Which steel is better for outdoor use?
- Both steels perform well outdoors; however, if you need maximum toughness for heavy-duty tasks like chopping or batoning, Elmax is better.
- Does cryogenic treatment improve both steels?
- Yes! Cryogenic treatment helps both steels by converting retained austenite into martensite, improving hardness.
- Why is M390 more expensive than Elmax?
- M390 has higher alloy content (especially vanadium), which increases production costs.
Citations:
[1] https://www.bladeforums.com/threads/elmax-vs-m390.813131/
[2] https://nobliecustomknives.com/m390-steel/
[3] https://nobliecustomknives.com/elmax-steel/
[4] https://knifesteelnerds.com/2020/03/30/m390-vs-20cv-vs-204p-3rd-generation-powder-metallurgy-technology/
[5] https://bladeops.com/elmax-steel/
[6] https://cdn.prod.website-files.com/65dccaa56e9f327ead622d79/66fb42a7c32c18d3273c487a_pesagolizebo.pdf
[7] https://coltellimania.com/en/elmax-steel/
[8] https://www.alphaknifesupply.com/shop/m390-stainless-steel
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