ISO/DIS 4948.2

Classification of steel based on chemical composition

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DRAFT INTERNATIONAL STANDARD
ISO/DIS 4948
ISO/TC 17 Secretariat: JISC
Voting begins on: Voting terminates on:
Corrected version
2019-11-08 2020-01-03
2019-11
Classification of steel based on chemical composition
ICS: 77.080.20
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ISO/DIS 4948:2019(E)
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ISO/DIS 4948:2019(E)
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ISO/DIS 4948:2019(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope .................................................................................................................................................................................................................................1

2 Normative references ......................................................................................................................................................................................1

3 Terms and definitions .....................................................................................................................................................................................1

4 Classification of steel........................................................................................................................................................................................1

4.1 General ........................................................................................................................................................................................................... 1

4.2 Non-alloy steels ...................................................................................................................................................................................... 1

4.3 Alloy steels .................................................................................................................................................................................................. 2

4.3.1 Stainless steels ................................................................................................................................................................... 2

4.3.2 Other alloy steels ............................................................................................................................................................. 2

Annex A (informative) Definition and classification of steel grades according to quality and

special steels ............................................................................................................................................................................................................. 4

Bibliography ................................................................................................................................................................................................................................7

© ISO 2019 – All rights reserved iii
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ISO/DIS 4948:2019(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

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URL: www .iso .org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 17, [Steel].
This document cancels the first edition (ISO 4948-1:1982 and ISO 4948-2:1981).
iv © ISO 2019 – All rights reserved
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DRAFT INTERNATIONAL STANDARD ISO/DIS 4948:2019(E)
Classification of steel based on chemical composition
1 Scope

This international standard provides guidance on the classification of the grades of steel included in the

product standards of and addressed by TC17 and its subcommittees. These grades may include but are

not limited to non-alloy and alloy steels.

The terms, special and quality steels are nowadays outdated. Nevertheless, they are used in standards

and the market. And therefore they can be found in Annex A.

NOTE 1 This standard does not intend to give any commercial information including tariff, residual elements

specification, and academic definitions for educational purposes.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.

ISO and IEC maintain terminological database for use in standardization at the following addresses.

— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC electropedia: available at http: //www .electropedia .org/
4 Classification of steel
4.1 General

Classification is based on the cast (heat) analysis specified in the product standard, and is determined

by the minimum value specified for each element. In the absence of a product standard, classification

may be based on the actual cast (heat) analysis reported by the manufacturer.

Where for other than manganese (see NOTE of Table 1) a maximum value only is specified in the

product standard or specification for the cast (heat) analysis, a value of 70 % of specified value shall be

taken for classification. (see Examples 1 and 2).
Table 1 is applied for classification of non-alloy steels and alloy steels.
NOTE 1 The definition of steel is given in ISO 4885, clause 3.195.

NOTE 2 General issues for delivery requirements should be dealt in accordance with ISO 404.

NOTE 3 Unkess otherwise specified, unit of chemical composition is mass percentage.

4.2 Non-alloy steels

Non-alloy steels are those in which the percentage of each element is less than the limiting values

specified in Table 1.

NOTE A small amount of alloying elements added to non-alloy steels may cause the product to be defined as

a micro-alloy steels.
© ISO 2019 – All rights reserved 1
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ISO/DIS 4948:2019(E)
4.3 Alloy steels

NOTE Alloy steels may be divided conveniently into micro-alloy steels, low-alloy steels and high-alloy steels.

The compositions limits are defined in the product standards.
4.3.1 Stainless steels

Steels that conforms to a specification that, requires, by mass percent, a minimum chromium content of

10,5 % or more, and a maximum carbon content of less than 1,20 %.

NOTE Stainless steels are classified into ferritic steels, martensitic steels, precipitation-hardening steels,

austenitic steels, austenitic-ferritic (duplex) steels, creep-resisting steels and heat resisting steels according to

their structure, composition and application.
4.3.2 Other alloy steels

Other alloy steels are those in which at least the percentage of one element is greater than or equal to

the limiting value given in Table 1.
Table 1 — Bou
...