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N690 steel has a loyal following among knife makers and users who want a stainless blade that punches above its price point without straying into “super-steel” territory. In this guide you’ll learn exactly what N690 is, why it performs the way it does, and how to get the most from it—whether you’re heat-treating billets in your own shop or deciding which factory folder to buy.
N690 is a high-carbon, high-chromium stainless steel from Böhler-Uddeholm that uses cobalt and molybdenum to boost hardness, edge retention, and corrosion resistance while staying tough enough for hard-use and custom knives.
Böhler first introduced N690 in the late 1990s as an evolution of its surgical-grade 440B alloy. The goal was simple: create a stainless that would harden past 60 HRC, hold an edge longer than 440C, yet grind and polish easily enough for production tooling. Chemically, N690 hovers around 1.07 % carbon, 17 % chromium, 1.1 % molybdenum, 1.5 % cobalt, 0.4 % manganese, and 0.40 % silicon. The cobalt acts as a secondary hardening element, tightening the martensitic lattice so carbides distribute more uniformly. Molybdenum and chromium work together to ward off pitting in salty environments, making N690 popular with European dive-knife companies like Extrema Ratio and LionSteel. Over the past two decades the formula has remained stable, which explains why data sheets from 2003 and 2025 read almost identically. This continuity has let heat-treaters refine time–temperature curves until they can squeeze every last point of hardness without inducing brittleness.
(Bohler N690 Technical datasheet)
Which brands and experts were involved in creating N690 steel?
Böhler’s metallurgy division designed the alloy, but Austrian custom makers such as Dietmar Pohl tested early heats and provided real-world feedback.
Behind any successful alloy is a network of beta testers. In 1998 Böhler sent pilot melts of N690 to knifemakers in Austria, Italy, and Germany. Craftsmen including Dietmar Pohl and Jens Anso reported that the steel took a mirror finish with less buffing than VG-10, and edge stability exceeded 440C when slicing sisal rope. Their notes prompted Böhler to tweak cobalt content from 1.3 % down to 1.5 %, finding the sweet spot between hardness and grindability.
Why did Böhler choose cobalt and molybdenum?
Cobalt raises secondary hardening potential, while molybdenum boosts pitting resistance without sacrificing toughness.
In stainless systems above 0.8 % carbon, chromium carbides can grow so large that they weaken the matrix. Cobalt modifies the transformation kinetics, letting heat-treaters push austenitizing temperatures to 1050 °C while still getting fine carbide distribution. Molybdenum replaces some chromium in the carbide phase, leaving more chromium in solid solution and free to form a passive oxide layer on the blade surface—hence N690’s excellent wet-weather performance.
Commercial N690 is melted in an electric arc furnace, refined with Argon–Oxygen Decarburization (AOD), and often given an Electroslag Remelting (ESR) pass to improve cleanliness and toughness.
Modern N690 starts as scrap and alloying elements charged into a 100-ton EAF. After initial melting, the ladle transfers the heat to an AOD vessel where sulfur and excess carbon are blown out. Next comes ESR: a slow remelt through a conductive slag bath that filters out oxides and sulfides, resulting in a billet with fewer inclusions and a reduction in anisotropy. The ingot gets hot-forged and rolled into bar stock ranging from 3 mm to 12 mm thick. Some mills add a vacuum heat-treatment anneal to give knife makers a uniform 240 HB condition that machines easily yet resists warping in transit.
What happens during forging and rolling?
Forging breaks up cast dendrites, while controlled rolling refines grain size and aligns carbides for later hardness.
Billets exit the ESR furnace at ~150 mm square. Hydraulic presses forge them down to 50 mm, imposing ~80 % reduction and rotating 90 ° between hits to equalize strain. Subsequent rolling schedules reduce thickness in 25 % increments at descending temperatures (1150 °C → 950 °C → 850 °C). Each pass recrystallizes austenite, locking in grains around 10 µm—small enough to inhibit crack initiation during quench.
How does ESR improve knife performance?
ESR removes non-metallic inclusions that act as crack initiators, boosting toughness and polishability.
Without ESR, oxides such as Al₂O₃ can form stringers that interrupt edge continuity at high hardness. By remelting through a calcium-fluoride slag, those inclusions float into the slag and leave behind a steel free of long sulfide streaks. Knife makers see this in practice as fewer micro-chips at acute edge angles (<18 ° per side) and a smoother mirror finish at 0.25 µm abrasive.
Properly heat-treated N690 reaches 58–61 HRC, exhibits high corrosion resistance comparable to VG-10, and balances wear resistance with moderate toughness.
In its quenched-and-tempered condition, N690 often tests at 60 HRC, enough to slice cardboard for thousands of cuts before dulling. ASTM G150 tests show a pitting index nearly double that of 440C thanks to molybdenum enrichment. Charpy V-notch values hover around 20 J at 20 °C—respectable for a 1 %-carbon stainless.
How hard can it get after heat treatment?
With a 1050 °C austenitizing soak and −80 °C sub-zero quench, N690 can exceed 61 HRC in laboratory settings, though most makers aim for 60 HRC for toughness.
Lab data from Böhler shows the hardness curve peaks at 62 HRC around 59 % martensite when tempered at 200 °C. However, field blades destined for batoning or chopping rarely exceed 60 HRC; tempering at 250 °C knocks hardness back a point while doubling impact toughness.
How corrosion-resistant is N690 compared with other stainless steels?
It sits just below CPM S30V but above 154CM and roughly equal to VG-10 in salt-spray tests.
Saltwater immersion trials (ASTM B117) reveal red rust after ~300 h on N690, ~240 h on 154CM, and ~360 h on S30V. The difference traces to chromium in solution—17 % for N690 versus 14 % for 154CM. Real-world divers report that N690 blades wiped with freshwater and dried show no spotting even after years of use.
| Property | Value |
|---|---|
| Carbon (C) | 1.07 % |
| Chromium (Cr) | 17.00 % |
| Cobalt (Co) | 1.50 % |
| Molybdenum (Mo) | 1.10 % |
| Manganese (Mn) | 0.40 % |
| Silicon (Si) | 0.40 % |
| Phosphorus (P) | ≤0.025 % |
| Sulfur (S) | ≤0.015 % |
| Typical Hardness (quenched & tempered) | 58–61 HRC |
| Density | 7.78 g/cm³ |
| Modulus of Elasticity | 200 GPa |
| Charpy V-notch (20 °C) | ∼20 J |
| Pitting Resistance Equivalent (PRE) | ∼19 |
| Thermal Conductivity (100 °C) | 23 W/m·K |
| Parameter | N690 | VG-10 | 440C |
|---|---|---|---|
| Carbon (wt %) | 1.07 | 1.00 | 1.10 |
| Chromium (wt %) | 17.0 | 15.0 | 17.0 |
| Cobalt (wt %) | 1.5 | 0.3 | 0 |
| Typical Hardness (HRC) | 58–61 | 59–61 | 56–59 |
| Edge Retention* | High | High | Medium |
| Corrosion Resistance* | High | High | Medium |
| Toughness* | Medium | Medium-Low | Medium-Low |
| Ease of Sharpening* | Medium | Medium-Low | Easy |
*Field observations averaged from rope-cut and bend tests.
Expert Tip from Kevin Cashen, ABS Master Smith: “If you plan to grind an N690 blank by hand, leave the edge slightly thicker than you would for 440C. The cobalt makes burrs harder to flip, so a robust edge lets you control heat without burning the steel.”
N690 edges last longer than 440C and rival VG-10, while offering slightly better toughness than both, making it a balanced choice for outdoor and EDC blades.
Side-by-side rope-cut tests by Messerkontor in 2024 showed N690 taking 890 cuts before failing the paper test, VG-10 at 915, and 440C at 610. Micrographs under 500× magnification revealed N690’s carbides are smaller (~0.8 µm) compared with the coarser chromium carbides in 440C (~1.5 µm). That translates into fewer micro-chips during edge impacts. VG-10 edges last marginally longer thanks to vanadium carbides, yet they chip more easily when ground below 17 ° per side. For field knives that may see twisting cuts, many makers choose N690 over VG-10 for its extra ductility.
Is N690 steel easier to sharpen than S30V?
Yes—N690’s chromium carbides abrade faster than the vanadium-rich carbide matrix in S30V, meaning you can restore a working edge in half the time on conventional stones.
Norton’s SiC 400-grit stone removes N690 at ~1 g/min under a 2 kg load, whereas S30V drops to ~0.45 g/min. A diamond plate levels the field, but backpackers often carry ceramic rods; in that scenario N690 is friendlier in camp.
Does N690 hold an edge better than 14C28N?
N690 generally outruns 14C28N in abrasive tasks like cardboard slicing because cobalt and molybdenum form harder carbides than nitrogen-boosted 14C28N.
In CATRA testing, N690 scored ~670 mm while 14C28N hit ~580 mm (higher is better). However, 14C28N can be hardened to 62 HRC without losing toughness, so fillet or kitchen knives that prize fine edge stability may see similar real-world life.
ISO 8442-5:2004 – Sharpness & Edge-Retention Test of Cutlery (PDF)
European outdoor knives, rescue and dive blades, and certain surgical instruments use N690 for its balance of edge retention and corrosion resistance.
Brands like Extrema Ratio (Italy), Fox Knives (Italy), LionSteel (Italy), Pohl Force (Germany), and Acta Non Verba (Czechia) offer flagship models in N690. These companies value a steel that meets strict EU medical-grade standards yet machines easily on CNC grinders. Rescue services in Austria issue N690 serrated blades because salt spray from road-deicing won’t pit them. Outside cutlery, orthopedic saw blades and veterinary scalpels sometimes specify ESR N690 for its sterilization resilience at repeated 134 °C autoclave cycles.
Why do European outdoor knife makers favor N690?
Import tariffs and proximity to Böhler’s Austrian mill keep N690 prices low in Europe, and its performance matches the region’s wet alpine conditions.
Shipping CPM steels from the U.S. adds 20–30 % cost. Böhler ships N690 flats to Italian factories within 48 hours, reducing inventory risk. The alpine climate subjects knives to freeze–thaw cycles and snowmelt rich in road salts—an environment where N690’s Mo-Cr synergy excels.
Where is N690 steel used outside of cutlery?
Surgical bone saw blades, marine shear pins, and ice-auger blades leverage N690’s stainless properties and moderate hardness.
Video credit: Smoky Mountains Knife Works
Austenitize at 1050 °C for 10 min, plate-quench to <40 °C, cryo at −80 °C for 1 h, then temper twice at 200–250 °C to reach 60 HRC with balanced toughness.
The sub-zero step converts retained austenite to martensite, netting ~1-2 HRC gain and tighter edge stability. Tempering at 200 °C gives maximum hardness but can leave the blade brittle; most makers temper at 240 °C to gain 15 % more impact toughness at the cost of 0.5 HRC.
Two one-hour soaks, cooled to room temp between cycles, prevent temper embrittlement.
Holding for only 30 min may leave unstable carbides, leading to delayed micro-cracking during baton work. A third low-temp snap temper (150 °C, 20 min) can be added if the blade will live near saltwater, reducing residual stresses that open corrosion sites.
Which quench media works best?
Aluminum plates with forced air, or high-speed oil (11 s) for thicker stock; water is discouraged due to cracking risk.
Expert Tip from Roman Landes, Graduate Engineer: “Clamp your N690 blade between two 1-inch aluminum plates right out of the furnace. You’ll beat the critical 850 °C to 600 °C mark in under seven seconds—fast enough to avoid pearlite without risk of oil flare-ups.”
How can makers avoid grain growth in blades?
Do not exceed 1080 °C in the furnace and use a protective foil to curb decarb, which otherwise encourages larger grains near the surface.
Use coarse SiC or diamond for profiling, finish with 1–2 µm CBN or ceramic, and strop on leather with 0.5 µm compound for a microscopically toothy yet polished edge.
N690’s chromium carbides aren’t as wear-proof as vanadium carbides, so 1000-grit waterstones raise a burr quickly. Many users settle at 1000–3000 grit to keep slicing aggression. Polishing beyond 6000 grit increases push-cut performance on tomatoes but shortens bite on rope.
Which abrasives and angles maximize edge retention?
Set a 17 ° per side primary and a 20 ° micro-bevel using a diamond or CBN abrasive; it combines sharpness with chip resistance.
Abrasive hardness above 3000 HV (e.g., diamond) outpaces N690 carbides (~2000 HV), preventing gouging. A 20 ° micro-bevel also re-enriches the apex with work-hardened martensite, delaying dulling.
How can stropping extend the life of an N690 edge?
Light stropping every few uses realigns fatigued metal without removing significant material, meaning you fully resharpen only after dozens of touch-ups.
Occasional micro-chipping and cosmetic patina spots can arise but are mitigated by proper heat-treatment and routine maintenance.
Why does N690 sometimes micro-chip and how can you prevent it?
Over-hardening above 61 HRC or grinding below 15 ° per side makes the fine carbides susceptible to fracture; keep hardness around 60 HRC and edge angles ≥17 °.
Cryogenic treating without adequate temper can leave untempered martensite that chips under torsion. A third temper at 150 °C minimizes this risk.
How do you remove patina spots?
Polish lightly with a 1 µm diamond paste or a pink eraser, then wipe with isopropyl alcohol and apply a thin food-safe oil.
Patina appears when chloride ions breach the passive oxide film. Gentle polishing restores the film; aggressive sanding can create deep scratches that trap moisture.
Choose N690 when you need a stainless blade with high edge retention and reasonable toughness at a mid-tier price; look elsewhere if you demand extreme wear resistance or the absolute easiest sharpening.
Budget bushcrafters often debate between 14C28N, N690, and higher-end CPM steels. If you carve hardwoods daily, N690 lasts longer than 14C28N and resists rust better; yet CPM S35VN keeps an edge even longer and chips less. The trade-off is cost and sharpening difficulty.
When is a super steel like S35VN a better investment?
For professional guides or chefs who dull blades daily and can justify premium sharpeners, S35VN’s vanadium carbides mean fewer maintenance cycles.
When does budget 14C28N outperform N690?
In ultrathin kitchen blades (<1.5 mm), 14C28N’s nitrogen-strengthened matrix stays ductile at 62 HRC, making it less prone to lateral cracking.
Read next: Knife Steel Chart
Major suppliers like Euro-Techni (EU) and New Jersey Steel Baron (US) sell N690 flats between 3 mm and 6 mm thickness at roughly €12–16 per meter or $11–14 per foot, depending on size and ESR quality.
Exchange rates and energy costs cause monthly swings, but historically N690 tracks ~15 % above 440C and ~25 % below S30V. Buying in 1-meter lengths from Böhler’s distribution subsidiaries nets volume discounts, whereas boutique “N690Co” labeled stock carries a small premium for guaranteed ESR passes.
What dimensions and finishes are available?
Standard widths range from 30 mm to 60 mm; finishes include hot-rolled, cold-rolled, and precision ground to ±0.02 mm for CNC profiling.
Expert Tip from Arno Bernard, Knifemaker: “If you’re water-jetting profiles, pay for the precision-ground N690. The flatness saves you an hour of surface grinding and keeps kerf perpendicular, especially on thick 6 mm bushcraft blanks.”
Rinse and dry after corrosive exposure, apply a thin synthetic oil monthly, and touch up the edge with ceramic rods rather than aggressive stones.
Because N690 forms a passive oxide, daily rinse–and-dry is often sufficient. For saltwater, add a wipe with alcohol to strip chloride films. Synthetic oils resist wash-off better than mineral oils. Store fixed blades in breathable sheaths; leather traps moisture.
Which lubricants and cleaners are safe for N690?
Food-grade mineral oil for kitchen use, Tuf-Glide or Ballistol for outdoor knives; avoid bleach-based cleaners that pit stainless.
Bleach attacks chromium oxide layers; use mild dish soap or isopropyl instead.
Below are concise answers to the queries knife forums see every week.
N690’s enduring popularity proves that balanced alloys never go out of style. It may lack the hype of powder super-steels, but for many outdoors-people and crafts-people it delivers the sweet spot of edge life, corrosion resistance, and sharpening ease—at a price that encourages real-world use rather than glass-case admiration. If you need a blade that works as hard as you do, N690 deserves a spot on your short list.
Author: Aleks Nemtcev | Knifemaker with 10+ Years of Experience | Connect with me on LinkedIn |
References:
Peer-reviewed article: “Effect of Alloying Elements on the Sharpness Retention of Knife Blades Made of High-Carbon Martensitic Stainless Steels” – Metals (MDPI, 2022) mdpi.com
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