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M390 favors abrasive edge retention; MagnaCut offers more toughness. Both score strongly for corrosion resistance. If your knife repeatedly cuts through abrasive material, M390 has a useful case. For mixed everyday tasks where resistance to chips matters more, we would generally favor MagnaCut, assuming the knives themselves suit you equally well.
Performance Ratings
For the science, we turn to Dr. Larrin Thomas of Knife Steel Nerds, who has kindly allowed us to share his ratings here.
The toughness score of 7 is for original Crucible MagnaCut. In written feedback to KnifeInformer, Dr. Thomas provided a toughness rating of 8.5 for Erasteel MagnaCut; his January 2026 testing explains the differences between the two versions. This table uses the original version.
| Property | Böhler M390 | CPM MagnaCut |
|---|---|---|
| Abrasive edge retention | ||
| Toughness | ||
| Corrosion resistance |
Heat treatment, hardness and geometry affect actual knives.
What You Gain With M390
M390's edge-retention rating of 6.5 sits above MagnaCut's 5. That is relevant when abrasive material gradually wears the edge down. It does not mean M390 stays sharp a fixed percentage longer. Böhler identifies it as a powder metallurgy stainless grade; Thomas's M390 research explains its relationship to 20CV and 204P.
Our 20CV steel profile covers this closely related grade, which shares M390’s ratings.
What You Gain With MagnaCut
Original MagnaCut rates 7 for toughness versus M390 at 3.5. That supports choosing MagnaCut when chips are a concern, but it does not mean every MagnaCut blade is twice as hard to damage. Tip shape, edge angle and heat treatment still matter.
Corrosion Resistance and Maintenance
Both are stainless and score strongly for corrosion resistance: M390 at 9 and MagnaCut at 9.5. That small published gap should not settle the purchase on its own, and neither score makes the entire knife rustproof. Clean residue from the blade and mechanism and dry them before storage. For either steel, diamond or cubic boron nitride (CBN) abrasives are a practical choice for a substantial repair or angle change. Keep smaller touch-ups manageable rather than waiting for a badly dull edge.
Is MagnaCut an Upgrade From M390?
It is an upgrade in some properties and a tradeoff in another. If your M390 knife already handles your cutting and care well, the steel alone is not a reason to replace it. If chipping is the problem, MagnaCut's higher toughness makes it worth a closer look. Choose a suitable grind and heat treatment as carefully as the alloy. Our knife steel guide puts those decisions in context.
Our MagnaCut steel profile explains its design and the production-version differences.
The M390 steel profile explains its alloy background, sharpening and everyday care.
Composition
Our steel composition guide explains what the elements do and how to read these values.
Böhler M390: Böhler average composition, mass %; selected elements, not a batch analysis. Böhler: M390 MICROCLEAN.
CPM MagnaCut: Niagara typical composition, mass %; selected elements, not a batch analysis. Niagara Specialty Metals: CPM MagnaCut.
| Element | Böhler M390 | CPM MagnaCut |
|---|---|---|
| Carbon (C) | 1.9% | 1.15% |
| Silicon (Si) | 0.7% | Not listed |
| Manganese (Mn) | 0.3% | Not listed |
| Chromium (Cr) | 20% | 10.7% |
| Molybdenum (Mo) | 1% | 2% |
| Vanadium (V) | 4% | 4% |
| Tungsten (W) | 0.6% | Not listed |
| Niobium (Nb) | Not listed | 2% |
| Nitrogen (N) | Not listed | 0.2% |
Compare Two Knife Steels
Sources and Update Notes
- Dr. Larrin Thomas: knife steel ratings
- Böhler: M390 Microclean
- Niagara Specialty Metals: CPM MagnaCut datasheet
- Dr. Larrin Thomas: M390, 20CV and 204P research
- Dr. Larrin Thomas: Erasteel and original MagnaCut · Research comparing the two versions; the numeric 8.5 rating was supplied separately in written feedback.
