Overview
ISO 4957:2018 - Tool steels is an international standard that specifies requirements for wrought tool steels used for tooling and tooling components. It covers four main groups: non-alloy cold‑work tool steels, alloy cold‑work tool steels, alloy hot‑work tool steels, and high‑speed tool steels. The standard applies to products produced by hot‑rolling, forging, cold‑drawing, cold‑rolling or powder metallurgy and defines delivery heat‑treatment and surface conditions.
Key topics and technical requirements
ISO 4957:2018 defines the technical framework suppliers and purchasers must follow. Major topics include:
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Scope and classification
- Classification and designation follow ISO 4948‑1 and ISO/TS 4949.
- Steel grades and internationally important grades are listed in the standard’s tables (see Tables 2, 4, 6 and 8).
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Delivery conditions
- Permitted surface conditions: hot‑worked (as rolled/forged), machined (ground/polished/turned/peeled/milled), or cold‑reduced.
- Default heat‑treatment delivery condition is annealed for most tool steels unless otherwise specified.
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Purchaser information
- Mandatory ordering data (quantity, product form, dimensions/tolerances, ISO 4957 reference, steel designation, heat‑treatment symbol, inspection document type).
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Chemical, mechanical and hardness requirements
- Chemical composition, hardness and mechanical property requirements are referenced in the standard tables; hardness‑tempering temperature guidance is provided in Annex A.
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Surface quality and machining allowances
- Surface classes for bars and plates reference ISO 9443 and ISO 7788; ground or finished products must be free from decarburization and surface imperfections.
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Inspection, testing and documentation
- Sampling, test methods and inspection documents align with ISO 10474 and relevant ISO test methods; Annex B covers supplementary requirements and Annex C lists comparable steel designations.
Practical applications and users
ISO 4957 is essential for ensuring consistent quality and interchangeability of tool steels used in:
- Cutting tools, dies, punches, molds and forming tools
- Cold‑work applications (stamping, blanking, cold forming)
- Hot‑work applications (forging, die casting, hot forming)
- High‑temperature machining tools (high‑speed steels)
Typical users:
- Steel producers and foundries
- Toolmakers and die shops
- Procurement and specification engineers
- Heat‑treatment and metallurgical laboratories
- Quality assurance and inspection teams
Related standards
Standards referenced within ISO 4957 include ISO 404 (delivery requirements), ISO 10474 (inspection documents), ISO 9443 and ISO 7788 (surface quality), ISO 4948‑1 and ISO/TS 4949 (classification/designation), and test standards such as ISO 6506 (Brinell) and ISO 6508 (Rockwell).
ISO 4957:2018 is the authoritative reference for specifying wrought tool steels, helping purchasers and suppliers agree on material grade, surface and heat‑treatment conditions, testing and documentation to ensure reliable tooling performance.