Overview
ISO 4957:2018 specifies internationally important wrought tool-steel grades across non-alloy cold-work, alloy cold-work, alloy hot-work and high-speed families. It also addresses several product routes and delivery conditions, but does not promise global availability or exact equivalence to ASTM, EN, JIS or proprietary grades.
Designation and acceptance
ISO 4957:2018, Edition 3, remains current after confirmation in 2023. It applies to hot-rolled, forged, cold-drawn, cold-rolled and certain powder-metallurgy products supplied in declared surface and heat-treatment conditions. The designation must be paired with product form, size, surface, condition, testing and the intended tool-manufacturing procedure; an ISO steel name alone is not a finished-tool specification.
Members and selection
| Designation | Selection context |
|---|---|
| Non-alloy cold-work steels | Use where simple heat treatment and section size can deliver the needed hardness without alloy-grade hardenability. |
| Alloy cold-work steels | Select from wear/toughness balance, hardenability, dimensional stability and processing route. |
| Alloy hot-work steels | Evaluate hot strength, thermal fatigue, temper resistance and cooling design. |
| High-speed steels | Match hot hardness and carbide system to cutting speed, toughness and grindability. |
Comparison framework
| Criterion | Decision context |
|---|---|
| International family | ISO groups steels by tool-service metallurgy but notes that listed grades may not be available in every country. |
| Manufacturing route | Conventional wrought and powder-metallurgy routes can have different cleanliness, carbide and size capabilities. |
| Delivery condition | Surface and heat-treatment condition are explicit purchasing attributes, not optional afterthoughts. |
| Cross-reference | Composition similarity to ASTM or regional names does not prove identical product, tolerances, tests or heat-treatment response. |
Performance
- Acceptance under ISO 4957 Tool Steels depends on the exact alloy or grade, delivered condition, product geometry and specified test basis rather than the standard number alone.
- The ISO list is intentionally selective and does not mean that every grade, dimension or route is commercially available in each market.
- Service suitability remains an engineering decision: cross-standard substitution needs product-level comparison, not a chemistry-only table or shared traditional grade name.
Orderable product scope
- Hot-rolled or forged tool-steel stock in forms covered by the order.
- Cold-drawn or cold-rolled tool-steel products with declared surface and condition.
- Powder-metallurgy tool-steel products where the selected grade and supplier route are qualified.
Processing
- Confirm soft-machining condition, spheroidization and stock allowance before tool manufacture.
- Develop heat treatment from the ISO grade, section size, furnace atmosphere and distortion tolerance.
- Validate final hardness, retained austenite/carbide condition and dimensional stability for the tool duty.
Applications
- Cold-forming and cutting tools using non-alloy or alloy cold-work grades.
- Hot extrusion, die-casting and forging tools using alloy hot-work grades.
- High-speed cutting and wear tooling where hot hardness and carbide control are critical.
Selection
- Confirm that ISO 4957 Tool Steels actually covers the required product form and manufacturing route before comparing grades or quotations.
- Select alloy or grade and delivered condition from service, fabrication, section size and required property evidence; do not infer condition from a trade name.
- Require a written technical comparison and responsible-engineer approval before substituting another standard, alloy, condition or product route.
Procurement
- State ISO 4957:2018, exact steel name, product route, form, dimensions and quantity.
- State surface and heat-treatment condition, hardness range, machining allowance and dimensional tolerances.
- Define macrostructure, decarburization, segregation, cleanliness and any special examination required.
- Require inspection document, heat/lot traceability, marking, packaging and the agreed final tool heat-treatment plan.