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Introduction to BS EN ISO 4957:2018

The BS EN ISO 4957:2018 standard specifies requirements for wrought tool steels, including non-alloy and alloy cold-work tool steels, alloy hot-work tool steels, and high-speed tool steels. This document is essential for manufacturers and users of tool steels, ensuring consistency in material properties and performance.

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Scope and Classification

The standard applies to hot-rolled, forged, cold-drawn, or cold-rolled products, as well as those produced by powder metallurgy. Tool steels are classified into four main categories:

• Non-alloy cold-work tool steels
• Alloy cold-work tool steels
• Alloy hot-work tool steels
• High-speed tool steels

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Key Requirements

The standard outlines mandatory information to be supplied by the purchaser, including product form, dimensions, and heat-treatment conditions. Key requirements include:

• Chemical composition: Specified for each steel grade in Tables 2, 4, 6, and 8.
• Mechanical properties: Hardness values in annealed and hardened conditions.
• Surface quality: Requirements for hot-worked, machined, or cold-reduced surfaces.

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Heat Treatment Conditions

The standard defines various heat-treatment conditions, including:

Condition	Symbol	Description
Untreated	+U	As-rolled or forged condition
Annealed	+A	Soft annealed for machining
Quenched and tempered	+QT	Hardened and tempered for specific hardness

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Inspection and Testing

Products must undergo inspection and testing to verify compliance with the standard. Key tests include:

• Chemical analysis: Cast and product analysis for specified elements.
• Hardness testing: Brinell or Rockwell hardness as per ISO 6506-1 and ISO 6508-1.
• Surface inspection: Visual or agreed-upon methods for surface quality.

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Technical Updates in 2018 Edition

The 2018 edition introduces several updates, including:

• Delivery condition normalized/normalized rolled.
• Updated surface quality standards (ISO 9443 for bars, ISO 7788 for plates).
• New clause for sorting and reprocessing.

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Application and Compliance

BS EN ISO 4957:2018 is critical for industries requiring high-performance tool steels, such as automotive, aerospace, and manufacturing. Compliance ensures material reliability and adherence to international standards.

For detailed chemical compositions and mechanical properties, refer to the complete standard document.