ISO 4948-1-1982 PDF

Full title and description

Steels — Classification — Part 1: Classification of steels into unalloyed and alloy steels based on chemical composition (ISO 4948-1:1982). This part of ISO 4948 defines the term "steel", establishes 2.0 % carbon as the usual dividing line between steel and cast iron, and provides rules for classifying melts (ladle analyses) into unalloyed and alloy steels on the basis of specified element limits.

Abstract

This short international standard sets out the chemical-composition criteria used to separate unalloyed (non-alloy) steels from alloy steels. Classification is based on specified limit values for common alloying elements in the ladle analysis, and 2.0 % carbon is retained as the practical cut-off between steel and cast iron.

General information

• Status: Published (confirmed at periodic review; under revision activity reported).
• Publication date: June 1982 (1982-06).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 77.080.20 (Steels).
• Edition / version: Edition 1 (1982).
• Number of pages: 2 pages (short Part 1 text providing classification tables and rules).

Scope

Applies to the classification of steels on the basis of chemical composition of the melt (ladle analysis). The standard defines steel (with 2.0 % carbon as the usual dividing line from cast iron) and provides the element limit values and rules that determine whether a given ladle analysis is treated as unalloyed (non-alloy) steel or as alloy steel for the purposes of designation and further classification by other standards.

Key topics and requirements

• Definition of "steel" for classification purposes, and the practical 2.0 % carbon dividing line versus cast iron.
• Classification criterion based on ladle (melt) analysis rather than finished-product testing.
• Threshold (limit) values for common elements (C, Mn, Si, Cr, Ni, Mo, V, Ti, etc.) used to distinguish unalloyed and alloy steels.
• Rules for treating elements present below or above specified values and how combined effects (multiple alloying elements) influence classification.
• Short normative tables and clear rules designed to be used together with other ISO steel product standards (which reference the ISO 4948 classification system).

Typical use and users

Used by steelmakers (to assign melt classifications), metallurgists, standards writers, materials engineers, procurement and quality-control personnel, testing laboratories, and manufacturers who need a common basis for specifying and ordering steels. It is often used as the chemical-composition classification reference in product standards and heat-treatment specifications.

Related standards

ISO 4948 is a multi‑part classification series. The most directly related document is ISO 4948-2:1981 (Classification of unalloyed and alloy steels according to main quality classes and main property or application characteristics). Work to revise/replace ISO 4948-1 has been progressed under ISO/DIS 4948-1 (draft revision). The ISO 4948 classification scheme is also referenced by many product and heat‑treatment standards (for example, parts of the ISO 683 series and regional/adopted versions that use ISO classification names).

Keywords

steel classification, unalloyed steel, alloy steel, chemical composition, ladle analysis, carbon limit 2.0%, ISO 4948, ISO/TC 17, melt analysis.

FAQ

Q: What is this standard?

A: ISO 4948-1:1982 is Part 1 of the ISO 4948 series; it specifies how to classify steels into unalloyed (non-alloy) and alloy steels on the basis of chemical composition (ladle analysis) and defines steel for classification purposes (using 2.0 % carbon as the usual dividing line from cast iron).

Q: What does it cover?

A: It covers the classification rules and limit values for chemical elements in the ladle/melt analysis that determine whether a steel is treated as unalloyed or as alloyed, together with short tables and procedural rules to support consistent designation across product standards.

Q: Who typically uses it?

A: Steel producers, foundries (for distinguishing steel vs cast iron), metallurgists, materials engineers, quality/control laboratories, standards committees and purchasers who need a clear, internationally accepted basis for chemical classification of steels.

Q: Is it current or superseded?

A: As published in 1982, ISO 4948-1 has been periodically reviewed and was confirmed at review; it remains published. However, ISO work to revise the Part 1 text has been started (a DIS/working draft has been issued as part of the ISO 4948 revision activity), so users should check for the newer DIS/updated part when requiring the very latest consolidated classification rules.

Q: Is it part of a series?

A: Yes — ISO 4948 is a multi‑part series. Part 1 addresses classification by chemical composition; Part 2 (ISO 4948-2:1981) addresses classification by quality classes and main property/application characteristics; other parts and related product standards reference the ISO 4948 scheme.

Q: What are the key keywords?

A: steel classification, unalloyed, alloy, chemical composition, ladle analysis, carbon 2.0%, ISO 4948, metallurgy.