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M390 offers higher corrosion resistance than S30V, with a smaller advantage in abrasive edge retention. S30V has a slight toughness lead. If you are considering an M390 version of a knife you already like, the most useful question is whether the extra rust resistance matters enough to justify the price.
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.
| Property | CPM S30V | Böhler M390 |
|---|---|---|
| Abrasive edge retention | ||
| Toughness | ||
| Corrosion resistance |
Heat treatment, hardness and geometry affect actual knives.
How Much of an Edge-Retention Upgrade Is M390?
M390 scores 6.5 for abrasive edge retention and S30V 6. That half-point difference favors M390, but it is too small to promise a noticeable improvement in every finished knife. It certainly does not mean every M390 blade stays sharp a fixed percentage longer.
Dr. Larrin Thomas’s analysis of CATRA tests on M390 and S30V knives shows why comparisons between models need care: hardness and edge geometry also affect the result. If the S30V knife has a thinner blade behind the edge, switching to a thicker M390 knife may make cutting feel worse despite the steel’s higher wear rating.
Our S30V steel profile explains the alloy behind this familiar pocket-knife option.
Corrosion Resistance Is the Clearer Separation
M390 rates 9 for corrosion resistance, compared with S30V at 7.5. We would give this difference more weight for humid pocket carry or frequent food cutting than for opening a few dry packages at a desk.
Both are stainless steels, and neither is maintenance-free. Rinse away food or salt residue and dry the blade. If your S30V knife has stayed clean with your normal care, M390’s additional corrosion resistance may not solve a problem you actually have.
The M390 steel profile takes a closer look at its properties and maintenance.
S30V’s Small Toughness Lead
S30V rates 4 for toughness and M390 3.5. We would not use that small gap to label one a hard-use steel and the other fragile. For a knife that chips in your work, look at the edge angle and the way it is being used before expecting this swap to fix it.
Both steels contain hard carbides. Diamond or cubic boron nitride (CBN) abrasives are useful sharpening options, especially for repairs. The ratings do not tell you how long either knife will take to sharpen.
When We Would Choose Each
With similar designs and prices, we would lean toward M390 when damp carry is a regular part of the job. S30V remains an easy choice when it comes in the model you prefer, especially if the M390 alternative costs substantially more.
For an existing S30V owner, this is usually a modest change rather than a reason to replace a good knife. Compare the actual blade, handle and sharpening needs before buying on the steel name alone.
Composition
Our steel composition guide explains what the elements do and how to read these values.
CPM S30V: Reported composition from Larrin Thomas’s July 2026 table, mass %; not a producer specification or batch analysis. This source lists 0.2% nitrogen for S30V; Niagara’s datasheet does not list nitrogen. Knife Steel Nerds: stainless steel composition table (July 2026).
Böhler M390: Böhler average composition, mass %; selected elements, not a batch analysis. Böhler: M390 MICROCLEAN.
| Element | CPM S30V | Böhler M390 |
|---|---|---|
| Carbon (C) | 1.45% | 1.9% |
| Chromium (Cr) | 14% | 20% |
| Molybdenum (Mo) | 2% | 1% |
| Vanadium (V) | 4% | 4% |
| Nitrogen (N) | 0.2% | Not listed |
| Silicon (Si) | Not listed | 0.7% |
| Manganese (Mn) | Not listed | 0.3% |
| Tungsten (W) | Not listed | 0.6% |
Compare Two Knife Steels
Sources and Update Notes
- Dr. Larrin Thomas: knife steel ratings · Property ratings; the scores describe steels rather than individual finished knives.
- Knife Steel Nerds: stainless steel composition table (July 2026)
- Böhler: M390 MICROCLEAN
- Knife Steel Nerds: CATRA tests of M390 knives · How geometry and test conditions complicate comparisons between finished knives.
