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Knife steel selection in a working knife shop

Knife steel

A2 knife steel

Air-hardening tool steel with a toughness-first reputation: Bark River’s longtime hard-use steel and the classic plane-iron alloy, tougher than D2 and easy to grind, with moderate wear resistance and carbon-steel rust care.

Also known as

  • AISI A2
  • DIN 1.2363
  • ~SKD-12

At a glance

How A2 behaves

The four meters are relative to the rest of the database. Composition is the published nominal analysis, not a mill certificate for your bar.

Working properties

Toughness
4 / 5
Edge retention
3 / 5
Corrosion resistance
2 / 5
Ease of grinding
4 / 5
Composition
  • Carbon1.00%
  • Chromium4.75–5.50%
  • Molybdenum0.90–1.40%
  • Vanadium0.15–0.50%
  • Manganese0.60–1.00%
  • Silicon~0.50%
Best uses

Hard-use outdoor knives: camp blades, choppers, survival and bushcraft knives where edge stability under abuse beats maximum wear resistance. Also excellent in tough-duty kitchen knives (with rust care), and the classic steel for woodworking plane irons and chisels. A strong first tool steel for stock-removal makers with kiln access.

Sources
  • Knife Steel Nerds — A2 Steel History and Properties (knifesteelnerds.com)
  • Hudson Tool Steel — A2 technical data
  • Lie-Nielsen Toolworks — A2 blade specifications

At the bench

What each property means for this steel

Open the property you are worried about. Every note is written for the blade in your hand, not for a spec sheet.

Toughness
The reason makers pick A2: clearly tougher than D2 and other high-carbide tool steels at working hardness — the classic choice for choppers and hard-use blades that must not chip. Modern PM steels like CPM 3V exceed it, at a price.
Edge retention
Moderate carbide volume holds a solid working edge — above simple carbon steels, clearly below D2 and the CPM class. Takes a notably fine, keen edge for a tool steel thanks to its restrained carbide structure.
Corrosion resistance
About 5% chromium: slows rust slightly versus 1084/1095 but this is tool steel, not stainless. It patinas and will rust if neglected — oil it, dry it, and consider a forced patina on users.
Grinding and machinability
One of the friendlier tool steels on the grinder and under files when annealed; finishes and hand-sands more cleanly than D2 or the PM steels.
Quench and temper decide whether A2 gives you the numbers above.

The full reference

More on A2

A2 is the tool steel that refuses to go out of style: an air-hardening workhorse that has spent decades as the steel behind Bark River’s hard-use knives and Lie-Nielsen’s plane irons. Its pitch is simple — noticeably tougher than D2, far easier to grind and finish than the PM steels, and capable of a keen, fine edge — in exchange for moderate wear resistance and carbon-steel-style rust care. For makers, it has one more quiet gift: it hardens in air, which makes it one of the friendliest tool steels to heat treat flat.

A2 FAQ

Is A2 stainless?

No. A2 carries about 5% chromium — enough to slow rust slightly and support air hardening, nowhere near the ~13%+ that stainless requires. Treat it like carbon steel: keep it oiled, expect a patina, and consider a forced patina for protection.

Fixed knife with walnut handle rests on a folded cloth beside a clear oil vial and a rumpled rag on a dark bench.

What hardness should A2 be heat treated to?

58–62 HRC is the working range. Austenitize at 1750–1800°F with a 30–45 minute soak, quench in air or between aluminum plates, and double temper — around 400°F lands near 60–62 HRC, 450–500°F trades a point of hardness for extra toughness. Lie-Nielsen runs its cryo-treated A2 irons at 60–62.

Gloved hands work the screw of a guided plate fixture; a flat blade blank lies on the lower plate beneath the raised upper plate.

Is A2 good for knives?

Genuinely, yes — especially hard-use blades. Its toughness-to-hardness balance made it Bark River’s signature steel for years of choppers and survival knives, and it takes a finer edge than its coarser tool-steel cousins. The tradeoffs: it needs rust care, and steels like CPM 3V now beat it on paper (at a price).

Stout fixed-blade knife with a walnut handle and cord lanyard lies on a leather pad before its sheath and a wood offcut.

A2 vs D2 — which should I pick?

A2 for toughness, ease of grinding, and a cleaner fine edge; D2 for wear resistance and slightly better stain resistance. Full breakdown in our A2 vs D2 comparison.

Ground knife blank with a bright blade beside a coarse maroon abrasive strip and a finer gray strip on a dark bench.

Head to head

Compare steel data for A2

Every matchup A2 appears in, dimension by dimension.

Browse the steel database

Keep reading

Guides that use this steel

More in this topic

Same bench

Grind A2 on a machine that holds still

Whatever the steel, the grind is only as flat as the platen behind it. I machine the parts, hand-assemble and test Torus grinders in Sterling, Illinois.

See the whole shop
  • Classic aluminum 2x72 grinder, side view with flat-platen tool arm and yellow Safety Rules label, on black with a purple glow

    Torus 2×72 Classic Aluminum Belt Grinder

    Prior-design aluminum chassis, 90-degree tilt and 1.5-inch tooling arms.

    Starts at$995View

One-man shop

Thinking about A2?

Tell me what the blade is for and how you heat treat. I will tell you whether this is the steel I would use, and what I would use instead.

Ask Rich a questionRun the Steel Selector