Beyond the Big Five: Other Steel Names on a Shear Listing
420J2, AUS-8, N690, M390, HAP40, ZDP-189, silver paper steel and house alloy names: what kind of name is it?
By JapanShears EditorialUpdated
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Sooner or later a listing names a steel you do not recognise. Decide what kind of name it is, then ask what the maker has published about the finished shear.
Short answer. Treat an unfamiliar steel name as a lead, not a verdict. Standard designations (420J2, 440A, AUS-8, 9Cr18MoV, SUS440C) describe a grade. Trade names (silver paper steel, house alloys) describe a supplier’s product. Powder and tool steels (M390, HAP40, ZDP-189) bring care and service questions. None of them states the heat treatment.
Key takeaways
- A grade name is a starting point. Heat treatment, geometry and finish decide the shear.
- Keep the designation exactly as printed. Do not swap SUS440C for 440C, or assume a country from a prefix.
- Some names here are not stainless, so wiping and oiling matter more.
- A house-branded steel name tells you about marketing until the maker publishes numbers.
- For VG-10, 440C, ATS-314, ZA-18, cobalt, powder metal and Damascus, see the steel library.
Which names sit at the entry end?
420J2 is a low-carbon stainless, also written 420B or “J2”. It turns up in student and consumer scissors and in instruments where corrosion resistance matters most. “Surgical grade” on a listing can point to a grade like it. Read that as a corrosion statement, not a sharpness one.
440A belongs to the 440 family but is its own grade. It is not an alias for 440B or 440C. Published finished-shear hardness for it varies between sources, so quote the maker’s figure for the model rather than a grade range. The name is not a Japan-origin guarantee either.
AUS-8 is a cutlery stainless described as 13Cr, 0.8C with molybdenum and vanadium. A mill datasheet describes the steel as supplied, not a finished shear, so an AUS-8 shear needs its maker’s hardness and treatment before you compare it with anything.
How do you read 9Cr18MoV and SUS440C?
9Cr18MoV is a naming code, and it shows how these names are built. The leading number is roughly the carbon content in tenths of a percent, the number after “Cr” is roughly the chromium percentage, and Mo and V mark molybdenum and vanadium. The designation states what the steel can reach, not what one batch achieved. The same grade is sold at different hardness depending on the mill’s hardening.
SUS440C is the Japanese Industrial Standard designation that corresponds to the 440C class. A manufacturer cross-reference lists the two in the same row. Keep whichever label the listing uses, and do not infer finished hardness or origin from the prefix.
What about N690 and the powder and tool steels?
| Name | What it is | What to check |
|---|---|---|
| N690 | A cobalt stainless with about 17% chromium on its datasheet | Can be sold under house branding without the grade named, so ask |
| M390 | A powder-metallurgy stainless with high carbon and about 20% chromium | Rare in scissors. Ask about the sharpening service for powder steels |
| HAP40 | A powder high-speed tool steel, mostly known from kitchen knives | Not stainless. It will rust without wiping and oiling after use |
| ZDP-189 | A powder stainless with about 3% carbon and about 20% chromium | Reported in the mid-60s HRC. Brittleness and specialist service are the trade-offs |
The mill’s own application line for ZDP-189 names cutlery tools, not scissors, so ask the maker about construction and care. Our powder metal guide covers the process term.
What are silver paper steel and Yasuki steel?
Silver paper steel (銀紙, gingami) is the stainless branch of a Japanese steelmaker’s paper-steel family. The silver grades, GIN-1 and GIN-3, are the ones whose published application lines name scissors. They are proprietary recipes rather than JIS-classified grades, and they often appear unlabelled.
Yasuki steel (安来鋼) is a brand name for the same steelmaker’s specialty cutlery steels. It is an umbrella, not a grade. Some well-known stainless names sit under it, so check whether a given product formally carries the brand.
What do house steel names mean?
Proprietary brand steels are trade names. A maker may sell under a tier name or an alloy name and disclose only part of the recipe. A name tells you the marketing tier. A published hardness, an alloy content and the maker’s care note tell you something about the metal. Where those are missing, record the steel as “not stated” rather than filling the gap.
What should you ask before you compare two steels?
- Is the name a designation, a trade name, a process or a construction?
- Does the maker publish finished-blade hardness, and on which scale?
- Is the steel stainless? If not, what care does the maker specify?
We sell shears and have not run cutting tests, so we do not rank steels. If you want the wider habit of reading a listing, the spec sheet walkthrough puts steel in its place among the other lines.
Common mistakes
- Treating a rarer name as a higher rating.
- Swapping one designation for another (SUS440C for 440C, 440A for 440C).
- Inferring hardness or origin from a prefix.
- Assuming every steel on a listing is stainless, and skipping the wipe and oil.
- Filling a missing recipe with a guess instead of recording “not stated”.
Questions people ask
Is a rarer steel name a better one?
No. Rarity is not a rating. Compare the finished model’s hardness, geometry and care notes.
Does “Japanese steel” mean smelted in Japan?
Not necessarily. The grade and recipe matter more than a country on the listing. See Japanese brand, Japanese steel or made in Japan.
Further reading
- Japanese shear steel library
- How Japanese shear steel names work
- HRC hardness on hair shears explained
- Powder metal in hair shears
- Forged, cast, heat-treated: what those listing words mean
- The knowledge base and the hair shear glossary.
- Scissorpedia for general scissor reference.
Scissorpedia is a fellow member of the ShearAlliance (see ShearAlliance).