M390

Overview

M390 is a premium powder metallurgy stainless steel built around high wear resistance and strong corrosion resistance. In knives, that means long working edge life in normal cutting and very good resistance to sweat, humidity, and food exposure.

The tradeoff is toughness and sharpening effort. M390 is not a hard-use toughness steel, and it is not the steel to pick if you want fast sharpening on simple stones.

Buy M390 for slicing and steady utility work, not for abuse. It can be excellent in a thin, well-made EDC folder. It can also be disappointing in a thick blade with a poor heat treatment.

Composition and History

M390 was developed by Bohler as a powder metallurgy stainless tool steel. Its knife performance comes from high carbon and chromium with vanadium, molybdenum, and tungsten additions. The powder metallurgy process helps distribute carbides more evenly than conventional high-alloy steelmaking.

In buyer terms, the chemistry gives M390 its edge life and corrosion resistance, but it also explains the sharpening cost. The hard carbides that help it keep cutting are the same reason basic abrasives can feel slow.

CPM 20CV and CTS-204P are close practical equivalents. In real use, the maker’s heat treatment, grind, and quality control usually matter more than choosing among those three labels.

Performance Tradeoffs

Edge Retention

Edge retention is the main reason to buy M390. It works well for cardboard, packaging, rope, plastic strapping, and other abrasive daily cutting where simpler stainless steels need more frequent touch-ups.

It is not automatically better in every knife. A thin S45VN or Elmax blade can outcut a thick M390 blade in normal use because geometry controls cutting feel. M390 helps most when the knife is already ground well.

Toughness

M390’s toughness is only fair compared with more balanced or tougher steels. That is acceptable for many folding knives, but it should shape how the knife is used.

Avoid twisting cuts, prying, chopping, and impact. If your work damages edges often, a tougher steel such as MagnaCut, S45VN, CruWear, or CPM-3V may be a better match.

Corrosion Resistance

M390 has outstanding corrosion resistance for a high-wear stainless knife steel. It is a good choice for pocket carry in humid climates, sweaty workdays, food prep, and users who do not want the upkeep of carbon or semi-stainless tool steels.

It is not maintenance-free. Clean off salt, blood, acidic food, and adhesive residue. Dry the knife before storage. That basic care is usually enough, but long-term neglect can still mark the blade.

Ease of Sharpening

Sharpening M390 is difficult compared with simpler steels. Diamond or CBN abrasives are the practical choice. Ceramic can work for touch-ups, but full reprofiling on basic stones can be slow and frustrating.

This is the steel to buy if you maintain an edge before it is dead. If you let knives get completely dull and then want a quick reset on a small pocket stone, M390 will feel like work.

Best Use Cases

M390 is strongest in knives that spend most of their life cutting, not being used as general tools.

Premium EDC folders for packaging, cardboard, and clean utility work
Office, warehouse, and trade carry where corrosion resistance matters
Users who want longer edge life and already own diamond sharpening equipment
Thin slicers where the maker uses good heat treatment and edge geometry
Collectors comparing premium stainless production knives

When Not to Choose

Not ideal for prying, twisting, scraping metal, chopping, or impact-heavy hard-use tasks.
Not a good match for users who only sharpen on basic soft stones.
Not the best value if you rarely cut abrasive material and mainly want easy upkeep.
Not the obvious pick if you regularly damage edges and need more toughness.

Practical Buying Guidance

M390 makes sense when the whole knife supports the steel’s strengths. Look for a thin grind, a reputable maker, and a heat treatment that is not treated as an afterthought.

Plan your sharpening setup before buying:

Use diamond or CBN stones for reprofiling and serious sharpening.
Use a ceramic rod or fine diamond plate for quick touch-ups.
Keep the edge angle realistic. Very thin edges cut well, but M390 is not the toughest choice if the edge will see side loading.
Consider a toothy finish for utility cutting instead of spending time on a high polish.

Comparison Context

Compare with S45VN to see where each steel wins in practical EDC use.
Compare with Elmax to see where each steel wins in practical EDC use.
Compare with MagnaCut to see where each steel wins in practical EDC use.
Compare with S90V to see where each steel wins in practical EDC use.
M390 vs S45VN: M390 usually offers better wear resistance and corrosion resistance. S45VN is generally easier to sharpen and more forgiving.
M390 vs Elmax: Both are premium powder metallurgy stainless steels. M390 leans more toward wear and corrosion resistance; Elmax is often treated as the more balanced option.
M390 vs MagnaCut: MagnaCut is usually the better all-around user steel if toughness and sharpening matter. M390 is better when edge retention and corrosion resistance are the priority.
M390 vs S90V: S90V pushes wear resistance further. M390 is usually easier to live with and more corrosion-focused for everyday carry.

Continue Learning

Read How to Choose Knife Steel by Use Case for a fast decision framework.
Read CATRA Myths for Buyers to interpret edge-retention claims correctly.