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Stainless Stainless Steel

"Stainless" means stain-resistant, not stain-proof. In kitchen use, the steel can still discolour or pit if exposed to acidic environments — citrus, vinegar, or salt water — for extended periods. Wash and wipe dry after every use, and avoid leaving the blade soaking in water. With basic care, a stainless knife is very low-maintenance and a great everyday choice.

ZA-18 ZA-18ステンレス鋼

Typical hardness Rockwell C Hardness(HRC) measures how resistant a steel is to permanent deformation. For kitchen knives:

55–58 HRC — Soft. Easy to sharpen and forgiving of rough use, but dulls faster. Typical of most German knives.
59–61 HRC — Balanced. Good edge retention with manageable sharpening. Common in mid-range Japanese knives.
62–64 HRC — Hard. Excellent edge retention, holds a very fine edge. Requires more care and a fine stone to sharpen.
65+ HRC — Very hard. Exceptional edge longevity but more brittle — more prone to chipping if used roughly.

Higher is not always better — it depends on how you use and maintain your knife.
60 to 62 HRC
555759616365+
We list ZA-18 knives in Sakai Takayuki's Ginga Damascus line (gyuto, santoku, nakiri, petty and sujihiki) and a Tsunehisa Damascus sujihiki.
Steel
ZA-18
Category
Stainless
Typical hardness
60 to 62 HRC

ZA-18 Composition

What's in ZA-18

What each element does in your knife.

ZA-18 element composition
Element Composition What it does in your knife
CrChromium 17.0–18.0% Raises corrosion resistance; at roughly 13%+ free chromium the steel qualifies as stainless. Also improves hardenability and wear.
CoCobalt 1.8% Allows higher hardening temperatures for more hardness and wear resistance, and strengthens the steel matrix.
MoMolybdenum 1.0–1.5% Improves hardenability and toughness, boosts corrosion resistance, and helps the steel hold hardness under heat.
CCarbon 0.95–1.2% The primary hardening element. More carbon means a harder edge that holds longer — but past a point it trades away toughness and rust resistance.
SiSilicon ≤ 1.0% Strengthens the steel matrix and acts as a deoxidiser, improving hardness and resistance to oxidation.
MnManganese ≤ 1.0% Aids hardenability and strength and acts as a deoxidiser in smelting. Too much can reduce toughness.
VVanadium 0.1–0.25% Forms extremely hard vanadium carbides for superior edge retention, and refines the grain for a finer, tougher edge.
PPhosphorus ≤ 0.04% An impurity from smelting. Even small amounts promote brittleness, so steelmakers keep it as low as possible.
SSulfur ≤ 0.03% An impurity that reduces toughness and promotes brittleness; only ever added deliberately in free-machining steels.

Composition from zknives (K&S steel dataset) reference material. These ranges come from the K&S steel composition dataset, which is derived from zknives; maker figures are cited separately only when they are used on the page.