M390
Blade steels
M390 Steel
Description
M390 is a powder metallurgy stainless steel from Böhler-Uddeholm, developed in the late 1980s as a modification of K190 for the plastics industry. One of the earliest stainless PM tool steels. Known for excellent corrosion resistance, high wear resistance, and exceptional edge retention. Commonly used in premium knives.
Composition
| Element | Content |
|---|---|
| Carbon (C) | 1.9 % |
| Chromium (Cr) | 20 % |
| Molybdenum (Mo) | 1.0 % |
| Vanadium (V) | 4.0 % |
| Tungsten (W) | 0.6 % |
| Manganese (Mn) | 0.3 % |
| Silicon (Si) | 0.3 % |
Properties
| Property | Value | Rating (1-10) |
|---|---|---|
| Hardness | 58–61 HRC | — |
| Toughness | Low (high carbide volume) | 4/10 |
| Corrosion Resistance | Very good (better than S30V, S35VN, S90V, SG2) | 9/10 |
| Wear Resistance | Very high (4 % vanadium) | 9/10 |
| Edge Retention (CATRA) | Very high | 9/10 |
| Sharpenability | Moderate (better than V-rich steels) | 5/10 |
Microstructure
M390 contains about 18 % chromium carbide and 2.5 % vanadium carbide. The high chromium content means much of the carbide volume is chromium carbide (lower hardness than vanadium carbide). PM manufacturing provides more uniform carbide distribution than conventional steels.
Heat Treatment
| Step | Temperature / Duration |
|---|---|
| Austenitizing | 1170–1200 °C |
| Quench | Air or oil |
| Cryo | Optional (improves hardness by 1–2 HRC) |
| Tempering | 180–220 °C (2–3× 2 hrs) |
| Achievable Hardness | 58–61 HRC |
Comparison with 20CV and 204P
| Steel | Manufacturer | Status |
|---|---|---|
| M390 | Böhler-Uddeholm | Original (patent 1989) |
| 20CV | Latrobe (later Crucible CPM-20CV) | Copy |
| CTS-204P | Carpenter | Copy (orig. Micromelt 20-4, 2009) |
All three are chemically nearly identical to M390.
Comparison with Related Steels
| Steel | Corrosion | Wear Resistance | Toughness | Edge Retention |
|---|---|---|---|---|
| M390 | 9/10 | 9/10 | 4/10 | 9/10 |
| S30V | 8/10 | 7/10 | 5/10 | 7/10 |
| S35VN | 8/10 | 7/10 | 7/10 | 7/10 |
| Elmax | 7/10 | 7/10 | 5/10 | 7/10 |
| 20CV | 9/10 | 9/10 | 4/10 | 9/10 |
| MagnaCut | 9/10 | 8/10 | 8/10 | 8/10 |
Pros and Cons
Pros:
- Excellent corrosion resistance (better than S30V, S35VN, S90V)
- Very high wear resistance and edge retention
- Good sharpenability despite high performance (moderate vanadium content)
- Proven PM steel for decades
- 20CV/204P available as lower-cost alternatives
Cons:
- Low toughness (high carbide volume)
- Relatively coarse PM carbides compared to newer steels
- Not ideal for thin edge geometries or high stress
- More expensive than conventional steels
Conclusion
M390 is one of the most established stainless PM high-performance steels. With excellent corrosion resistance, high wear resistance, and exceptional edge retention, it is a top choice for premium knives. The low toughness requires robust blade geometries. For better toughness with similar performance, MagnaCut is a modern alternative.