Böhler M390 and M398 are high-performance martensitic chromium steels produced via powder metallurgy. While M390 is a "balanced" super steel, M398 is an evolution specifically designed to maximize wear resistance and edge retention by significantly increasing carbon and vanadium content.
Key Differences
The primary difference lies in the carbide volume. M398 has approximately 30% total carbide volume compared to M390’s 20%. This translates to several performance shifts:
Feature | Böhler M390 | Böhler M398 |
|---|---|---|
Edge Retention | Very High | Exceptional (Top-tier for stainless) |
Toughness | Medium | Very Low (High risk of chipping) |
Corrosion Resistance | Very High | Very High (Slightly lower than M390) |
Sharpenability | Demanding (Needs diamonds) | Very Difficult (Abrasive resistant) |
Typical Hardness | 60–62 HRC | 63–67 HRC |
Composition Comparison
M398 adds significantly more alloying elements to the M390 "recipe" to form harder carbides:
Carbon (C): M390 (~1.9%) vs. M398 (~2.7%) — Supports massive carbide formation.
Vanadium (V): M390 (4.0%) vs. M398 (7.2%) — Creates extremely hard vanadium carbides for maximum edge life.
Chromium (Cr): Both remain at ~20% for excellent stainless properties.
Primary Applications
M390 Steel: The "industry standard" for high-end EDC (Everyday Carry) and production folding knives. It is ideal for users who want long-lasting sharpness without sacrificing too much toughness for general slicing tasks like cardboard, food prep, and rope.
M398 Steel: Reserved for smaller, high-performance cutters where absolute edge retention is the priority. It is commonly used in custom hunting knives and specialized folding knives where the user values staying sharp through massive amounts of abrasive material. It is not recommended for heavy-duty tasks or impact work (like chopping or prying) due to its brittleness.
Recommendation: Stick with M390 for a reliable, all-around pocket knife. Choose M398 if you are a "steel nerd" specifically looking for the longest edge life possible and have the diamond sharpening equipment to maintain it.