What do knife steel names actually mean?

Walk a knife counter and the names come at you like part numbers: 1095, 14C28N, D2, CPM S30V, M390. They look like specifications. They’re closer to recipe titles — each one points at a published chemical composition, usually a page on a steel mill’s website that almost nobody opens.

The name is worth reading. It just answers a narrower question than most buyers assume: not “is this a good knife,” but “which compromise did the maker start from.” The other half of the answer — the heat treatment — never appears in the name, and it’s the half that decides how the recipe turns out.

What does a steel name actually tell you?

A steel name identifies a published composition — the percentages of carbon, chromium, and other elements in the melt — and says nothing about how the blade was hardened. Crucible’s datasheet for CPM S30V is typical: 1.45% carbon, 14% chromium, 4% vanadium, 2% molybdenum, and a stated design goal — “the best combination of toughness, wear resistance and corrosion resistance.” That’s the whole disclosure. Everything the finished knife does with that recipe depends on decisions the name doesn’t record.

The names themselves follow no single system. 1095 comes from the old AISI numbering for plain carbon steels — its published carbon content is 0.90–1.03%, right where the name’s last two digits point, with no meaningful chromium. Alleima’s 14C28N is a Swedish mill’s catalog code for a stainless holding 0.62% carbon, 14% chromium, and 0.11% nitrogen, with a chemistry “optimized for high quality professional knife applications” — and some names carry history, too: Kershaw says that steel “was developed in a partnership between Kershaw and a Swedish engineering company specializing in stainless and special steel alloys,” per its blade steels page. The CPM prefix on Crucible grades marks their particle-metallurgy process, which the S35VN datasheet says “produces very homogeneous, high quality steel.” And Böhler’s M390 — 1.9% carbon, 20% chromium — isn’t even cataloged as a knife steel: Böhler files it under “plastic mould steels,” tooling for injection molds. Knife makers adopted it because the recipe happens to suit blades.

What’s the three-way trade every steel makes?

Every composition is a position in a triangle — edge retention, toughness, corrosion resistance — and pushing toward one corner pulls away from another. Larrin Thomas, the metallurgist behind Knife Steel Nerds, puts it flatly in his steel ratings: “Toughness and edge retention are generally opposing properties and it is difficult to improve both of them at the same time.” The mills say the same thing in their own words — Alleima’s knife steel guide notes that “high corrosion resistance involves sacrifices in edge performance.”

The mechanics are plain enough. Carbon plus strong carbide formers means hard carbide particles that resist wear — that’s edge retention, and it’s measurable: Crucible rates S30V’s edge retention at 145% of 440C, an older stainless benchmark, in CATRA testing, crediting a chemistry “specially balanced to promote the formation of vanadium carbides which are harder and more effective than chromium carbides.” Those same particles are fracture points, which is why carbide-rich steels chip sooner — the toughness cost. And chromium only fights rust while it stays free in the steel; chromium pulled into carbides doesn’t. Small recipe changes move the point: Crucible’s S35VN swaps in niobium and comes out, per its datasheet, “about 15-20% tougher than CPM S30V without any loss of wear resistance.” One more cost hides in the wear corner: carbide-rich steels are as stubborn against a whetstone as against cardboard, which is worth knowing before you pick a target geometry — see our guide to sharpening angles.

How do the common steels compare?

Eight recipes cover most of what serious production knives are sold in, and they differ mainly in which corner of the triangle they favor. Each steel name below links to the published composition its figures come from.

Steel	Carbon	Chromium	The trade it makes	Roster maker (verified)
1095	0.90–1.03%	none to speak of — not stainless	Tough, cheap, quick to sharpen; rusts without care	ESEE, as its standard blade steel
12C27	0.6%	13.5% — stainless	Easy-care, easy-grinding; modest edge life	Morakniv, in its stainless models
14C28N	0.62%	14% — stainless, plus 0.11% nitrogen	Keener-running stainless; nitrogen adds hardness without extra carbide	Kershaw, which co-developed it
420HC	0.46%	13% — stainless	Soft but very rust-resistant; fastest to resharpen	Kershaw (58 HRC, per its chart)
D2	1.50%	12% — semi-stainless	Near-stainless wear resistance; can still spot-rust	CRKT, across several models
S30V	1.45%	14% — stainless	Balanced high end: retention and corrosion, mid toughness	Benchmade (Bugout, 940 Osborne)
S35VN	1.40%	14% — stainless, plus 0.5% niobium	S30V re-tuned: tougher, same wear resistance	Spyderco (Persistence Lightweight)
M390	1.90%	20% — stainless	Maximum wear and corrosion resistance; slow to sharpen	None we’ve verified in our roster’s standard lineup

Compositions are the mills’ nominal published figures; “the trade” assumes typical production hardness, which the name alone doesn’t guarantee.

One disagreement in that last row is worth naming. Böhler lists M390’s toughness as “good”; Knife Steel Nerds’ independent ratings put its toughness near the bottom of the knife steels scored. A mold-tooling datasheet and a thin cutting edge judge toughness on different curves — read it as a difference in test, not a scandal.

Why does the same steel act differently in two knives?

Because the name only fixes the recipe — hardness comes from heat treatment, and two makers can run the same steel several Rockwell points apart. Latrobe’s 420HC datasheet describes “an attainable hardness of approximately 55 HRC” from its standard treatment; Kershaw lists its 420HC blades at 58 HRC. Likewise, Crucible’s recommended aim for S35VN is 58–61 HRC, while Kershaw states 60–62 for its own S35VN blades. None of these numbers is wrong. Hardness is a per-model choice about where to sit on the toughness curve, made in a furnace you’ll never see.

Buck — not a maker we cover, but the clearest example going — built its reputation on exactly this gap: an ordinary steel it describes as providing “excellent rust resistance, ease of re-sharpening and medium edge retention”, run through the program of Paul Bos, “widely recognized as America’s foremost heat treat authority for knife blades.” The steel name on the blade is unremarkable. The behavior is the heat treat.

Which makers actually publish hardness?

Fewer than publish steel names — and checking for the number is a fast read on how much a maker wants to be held to it. Benchmade states its S30V blades are heat-treated to 58–61 HRC. Kershaw publishes a per-steel chart — 14C28N at 58–60, D2 at 59–60. Morakniv names its suppliers outright — “Alleima in Sandviken, Sweden, has been our stainless steel supplier for nearly a century” — and states its laminated carbon core runs about 59 HRC. Buck’s D2 blog commits to “RC 58-61.” Opinel runs the disclosure backwards: its stainless product pages print “Hardness 55-57 HRC” while naming the steel only as a “martensitic stainless steel” of “European origin” — though its Carbone line is labeled plainly as XC90 carbon steel.

The other pattern is name-but-no-number. Spyderco’s page for the Persistence Lightweight in CPM S35VN details the steel’s niobium chemistry but lists no hardness; CRKT’s blade steel guide rates its steels on four qualities without an HRC anywhere; Case’s blade-material page publishes neither composition nor hardness for its “Tru-Sharp surgical steel,” describing it only as an alloy “with a high percentage of chromium.” A missing number isn’t proof of a poor heat treat. But a maker who publishes one is inviting you to check their work, and that’s the posture worth rewarding.

Does the steel name tell you whether a knife will rust?

Partly — the chromium percentage predicts the tendency, but no name makes a blade rust-proof, and the carbon-steel makers say so themselves. ESEE builds in 1095 and states it plainly in its FAQ: the blades “will rust and stain if not properly cared for,” which is why its carbon-steel models ship with a powder coat finish and the company suggests “a dry film rust inhibitor such as TUF-GLIDE or TUF-CLOTH.” Opinel sells near-identical knives both ways and lays out the trade on its own comparison page: carbon blades are “easier to sharpen” but “can rust and become stained,” while stainless blades “require less maintenance” but “tend to lose their cutting edge more quickly than carbon blades.” Case is just as direct about its Chrome Vanadium line: CV “is not corrosion-resistant and is therefore prone to tarnish and rust when exposed to air and moisture,” per its blade-material page. And stainless only ever means slower — for what 13–14% chromium actually buys you around salt water and acidic food, see our guide to whether stainless knives rust.

The short version

A steel name is a recipe reference, not a performance rating. Read it for the trade it encodes — carbon and vanadium push toward edge retention, free chromium toward rust resistance, simplicity toward toughness, and no recipe collects all three. Then look for the number the name leaves out: the hardness, which tells you how the maker actually cooked that recipe. Makers that publish both halves, the way Benchmade, Kershaw, Morakniv, and Opinel do in their different ways, are giving you a checkable answer. A steel name alone is half of one.