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GB/T 9943-2025High-speed tool steels (English PDF)

高速工具钢

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Issued by

SAMR; SAC

Level / Type

National · Recommended

Issue date

August 1, 2025

Implementation date

February 1, 2026

Scope

GB/T 9943-2025 is the English-translated version of 高速工具钢.

GB/T 9943-2025 is the Chinese national standard covering the ledeburitic tool steels that hold their hardness at around 600 °C — the tungsten and tungsten-molybdenum grades and the low-alloy, ordinary and high-performance classes, the chemical composition, the smelting route from ladle refining to powder metallurgy and spray forming, the dimensions and deviations for bars, wire, plate and pre-hardened bar, the test methods and inspection rules, and the bulk carbide evaluation that decides whether a cutting edge will chip. It replaces GB/T 9943-2008, under the China Iron and Steel Association. In force from 1 February 2026. Issued on 1 August 2025, it has been in force since 1 February 2026, replacing GB/T 9943-2008.

Document preview — GB/T 9943-2025

National Standard of the People's Republic of China

ICS: 77.140.35
Classification: H 40
Replacing: GB/T 9943-2008

Issued by: State Administration for Market Regulation; Standardization Administration of the PRC

Foreword3
1 Scope6
2 Normative references6
3 Terms and definitions8
4 Classification8
5 Ordering information8
6 Manufacturing process9
7 Technical requirements9
8 Test methods21
9 Inspection rules23
10 Packaging, marking, quality certificates24
Appendix A (Informative) Main characteristics and applications of high-speed tool steels25
Appendix B (Informative) Basic characteristics of high-speed tool steel28
Appendix C (Informative) Comparison of designations in this document with foreign designations29
Appendix D (Normative) Inspection and evaluation methods for bulk carbides30

1 Scope

This document specifies the ordering details, classification, dimensions, shape and permissible deviations, technical requirements, test methods, inspection rules, packaging, marking and quality certificates for high-speed tool steel.

This document applies to hot-rolled and forged high-speed tool steel bars (round bars, square bars, flat bars, hexagonal bars, etc., hereinafter referred to as steel bars), wire rods, wires, bright steel bars, which have a nominal size (diameter, side length, thickness, or distance between opposite sides) not exceeding 350 mm; cold-rolled steel plates which have a nominal thickness not exceeding 4 mm and hot-rolled steel plates which have a nominal thickness not exceeding 15 mm; pre-hardened high-speed tool steel bars which have a nominal diameter of 1.0 mm ~ 15.0 mm and a polished or cold- drawn surface (all collectively referred to as steel products). The chemical composition also applies to steel ingots and billets.

2 Normative references

GB/T 223

GB/T 224

GB/T 226

GB/T 230.1

GB/T 231.1

GB/T 247

GB/T 702

GB/T 708-2019

3 Terms and definitions

The terms and definitions defined in GB/T 20566, as well as the following terms and definitions, apply to this document.

3.1 High-speed tool steel

A high-carbon, high-alloy ledeburitic tool steel with tungsten, molybdenum, chromium, vanadium (some also contain cobalt) as the main alloying elements, possessing high red hardness (maintaining high hardness at approximately 600 °C) and excellent wear resistance.

Note. See Appendix A for main characteristics and applications.

3.2 Pre-hardening

Pre-hardening refers to the process of heat treatment to bring the material to a specific hardness level required for service before manufacturing.

4 Classification

4.1 High-speed tool steels can be classified into two types based on chemical

composition.

a) Tungsten-based high-speed tool steel;

b) Tungsten-molybdenum-based high-speed tool steel.

4.2 High-speed tool steels can be classified into three types based on performance.

a) Low-alloy high-speed tool steel (HSS-L);

b) Ordinary high-speed tool steel (HSS);

c) High-performance high-speed tool steel (HSS-E or HSSE).

Note. See Appendix B for the basic characteristics of different categories of high-speed tool steels.

5 Ordering information

Contracts or orders placed according to this document shall include the following.

a) Document number;

b) Product name;

c) Designation;

d) Cross-sectional shape (round, square, flat, hexagonal, etc.);

e) Dimensions and shape;

f) Weight (or quantity);

g) Delivery condition;

h) Special requirements (if any, see 7.7).

6 Manufacturing process

6.1 Smelting method

Steel shall be smelted by ladle refining or electroslag remelting, or by powder metallurgy or spray forming.

6.2 Delivery condition

6.2.1 Steel (except pre-hardened steel bars) shall be delivered in the annealed condition,

or annealed and then processed by other methods.

6.2.2 Pre-hardened steel bars shall be made from annealed steel bars or coiled steel wire that has undergone continuous pre-hardening treatment after uncoiling. Delivery shall be in straight bars after pre-hardening treatment or after further polishing. Specific requirements shall be specified in the contract.

7 Technical requirements

7.1 Designation and chemical composition

7.1.1 The designation and chemical composition (smelting analysis) of the steel shall

conform to the provisions of Table 1. ......

......
This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 19 pages — is available in the English PDF.

Referenced standards

Normative references

GB/T 223 · GB/T 224

Editions of GB/T 9943

Edition	Title	Revision	Status
GB/T 9943-2025	High-speed tool steels	current edition	Current
GB/T 9943-2008	High-speed tool steels	previous edition	In force
GB/T 9943-1988	High speed tool steel bars--Technical requirements	previous edition	Obsolete

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