440C Steel: Grade Scope, Composition and Scissor Evidence

Quick answerShort answer

440C is useful as a search and catalogue label. By itself, it is not a complete material record. It does not name a standard edition, producer, product form, material condition, heat, lot or finished part.

One exact material reference is Carpenter Technology’s CarTech 440C, identified in its official datasheet as UNS S44004. That sheet publishes a type analysis and heat-treatment context for Carpenter’s material. It does not certify every material sold as 440C, and it does not specify a finished hair scissor.

Reference sectionKeep three evidence levels separate

All three records can be useful. The important step is to keep their scopes visible. Material data should not be promoted into a finished-scissor claim without a traceable link to the exact product.

Reference sectionOne producer-bounded composition

Carpenter Technology’s CarTech 440C datasheet identifies the material as UNS S44004. It gives the following type analysis by mass. Carpenter labels single figures as nominal unless the table marks them as maximum values.

These values reproduce Carpenter’s published type analysis. They are not a certificate for a shipment, a different producer’s material or a finished blade. Elements absent from this table are unreported in this source, not zero.

The PDF carries an edition date of 1 June 1987 and remains hosted on Carpenter’s official site. Its disclaimer describes the data as typical or average values rather than guaranteed maximum or minimum values. A current purchase or production record should therefore identify the applicable specification, material form, condition and certificate for the stock actually supplied.

Reference sectionStandard and designation boundaries

ASTM A276/A276M-25 is the active ASTM specification for stainless steel bars and shapes. Carpenter lists ASTM A276 among the specifications applicable to CarTech 440C and lists bar, billet, wire and wire rod among its manufactured forms. Neither reference says that every item labelled 440C complies with ASTM A276. The ASTM standard also does not cover a completed hair scissor as a finished product.

JIS G 4303:2021 is the active Japanese Industrial Standard for hot-worked stainless steel bars. The Japanese Standards Association records that the 2021 edition was confirmed on 20 October 2025. Its scope is material in the listed bar forms, not finished scissors.

The Japan Stainless Steel Association comparison table places SUS440C in a comparison row with UNS S44004 and 440C. The association cautions that the table does not guarantee interchangeability or equivalence because composition, properties and test requirements can differ between standards. Use it to locate the relevant current documents, not to erase the designation printed in a source. A claim of SUS440C should stay SUS440C and should point to its JIS basis. A bare 440C claim still needs its own producer, specification, form and traceability.

Reference sectionHardness without a universal band

Carpenter says heat-treated CarTech 440C attains about Rockwell C 60. Its tempering section gives approximately the same value under the process described in the datasheet. This is a producer-specific, process-conditioned material statement. It is not a universal HRC rule for 440C and not a measurement from a finished scissor.

ASTM E18-25 defines Rockwell hardness testing for metallic materials. ASTM also explains that a result at one location on a part may not represent the whole part or end product. A useful finished-blade record should state:

1. whether the value is a design target, allowed range or measured result;
2. the Rockwell scale and test method;
3. the blade, part and test location;
4. whether the result applies to a sample, production lot or exact item; and
5. the tolerance, report date and responsible organisation.

Even a complete hardness result answers a hardness question only. It does not document blade geometry, assembly, intended use or cutting life.

Reference sectionWhat the label does not settle

The reviewed primary sources do not support universal 440C claims for:

• edge life measured in cuts, clients, weeks, months or years;
• a service interval, sharpening method or sharpening difficulty;
• toughness, drop response, chipping, rolling or another damage mode;
• a corrosion result in salon use or with a named product;
• country-based quality, manufacturing quality or consistency;
• price, value, market tier or ownership cost;
• blade weight, balance, feel, flex, glide or cutting technique; or
• superiority or equivalence between finished scissors.

These are evidence limits, not negative findings about any maker or model. Some manufacturers publish detailed product records and some publish only selected fields. Use each statement within the scope the source gives it.

Reference sectionExact finished-shear checklist

Use the grade name as one field in the record for a scissor, not as the whole record.

Mizutani Scissors gives a useful manufacturer boundary on its SOLID product and heat-treatment page. It explains that the same steel material can behave differently after different heat treatments and that a finished blade balances structure, blade angle and hardness. That supports checking maker execution. It does not provide 440C composition, certify another maker’s scissor or establish a universal performance result.

Reference sectionPrimary source boundaries

Sources and labels were checked on 22 July 2026. No technical claim on this page relies on a retailer steel guide, marketplace listing, generic steel chart or product photograph.

Related: Steel Types, Composition Guide and Hardness Reference.