ISO 28401:2010

Light metals and their alloys - Titanium and titanium alloys - Classification and terminology

ISO 28401:2010 gives a classification of titanium and titanium alloys. It also gives terms and definitions in the field of titanium and its alloys.

Métaux légers et leurs alliages — Titane et alliages de titane — Classification et terminologie

General Information

• Status: Published
• Publication Date: 22-Nov-2010
• ICS: 01.040.77 - Metallurgy (Vocabularies)
• ICS: 77.120.50 - Titanium and titanium alloys
• Technical Committee: ISO/TC 79/SC 11 - Titanium
• Drafting Committee: ISO/TC 79/SC 11 - Titanium
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 12-Aug-2024
• Completion Date: 13-Dec-2025

Relations

• Revised: ISO 28401:2024 - Light metals and their alloys - Titanium and titanium alloys - Vocabulary
• Effective Date: 06-Jun-2022

Overview - ISO 28401:2010 (Titanium classification and terminology)

ISO 28401:2010 is an international standard that defines a systematic classification and the terminology used for titanium and titanium alloys. It provides unified terms and definitions covering materials (e.g., titanium sponge), product forms (unwrought, wrought, castings), processing and heat-treatment methods, surface condition, melting methods and grade classification (including commercially pure titanium and alloy grades). The standard helps ensure consistent communication across industry, procurement and technical documentation.

Key topics and technical scope

ISO 28401:2010 addresses:

• Material definitions - e.g., titanium sponge, alloy, alloying element, impurity, master alloy, heat‑treatable vs non‑heat‑treatable alloys.
• Product classification - comprehensive definitions for unwrought and wrought products: ingots (for rolling/extruding/forging/remelting), billets, rod/bar, wire, tube, profile/shape, plate (>5 mm), sheet (0.20–5 mm), strip (>0.20 mm) and foil (≤0.20 mm).
• Casting methods - sand/graphite, permanent‑mould, die casting, centrifugal, investment casting, skull melting, and post‑casting HIP (hot isostatic pressing).
• Processing and heat treatments - alpha–beta and beta processing, annealing, ageing, cold working, bright annealing, beta‑transus concept.
• Melting method abbreviations - EB (electron beam), VAR (vacuum arc remelting), VASM, PM (powder metallurgy) listed for ingot/remelt categories.
• Classification & grades - separation of commercially pure (CP) titanium, corrosion‑resistance‑enhanced CP grades, titanium alloys (including common reference to Ti‑6Al‑4V as a high‑strength standard alloy), and titanium‑base intermetallics.
• Normative annexes - criteria such as the dividing line between titanium and titanium alloys and notes on wrought product classification.

Practical applications and benefits

ISO 28401 is used to:

• Standardize specifications and procurement language for titanium materials and products.
• Guide material selection and designation for engineering, fabrication and quality control.
• Support consistent classification across supply chains in aerospace, medical devices, chemical processing, marine and power generation where titanium’s corrosion resistance and strength‑to‑weight ratio are critical.
• Facilitate clearer technical documentation, testing protocols and regulatory submissions.

Who should use this standard

• Materials and metallurgical engineers
• Product designers and manufacturing engineers
• Procurement and quality assurance teams
• Specification writers and standards committees
• Aerospace, medical, chemical process and marine industry professionals

Related standards and keywords

ISO 28401 complements other ISO standards on product specifications, testing and surface treatments for light metals. Relevant keywords for search and discovery: ISO 28401, titanium classification, titanium alloys terminology, commercially pure titanium, Ti‑6Al‑4V, titanium processing, titanium castings, wrought titanium products.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 28401
First edition
2010-12-01
Light metals and their alloys — Titanium
and titanium alloys — Classification and
terminology
Métaux légers et leurs alliages — Titane et alliages de titane —
Classification et terminologie

Reference number
©
ISO 2010
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©  ISO 2010
The reproduction of the terms and definitions contained in this International Standard is permitted in teaching manuals, instruction
booklets, technical publications and journals for strictly educational or implementation purposes. The conditions for such reproduction are:
that no modifications are made to the terms and definitions; that such reproduction is not permitted for dictionaries or similar publications
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ii © ISO 2010 – All rights reserved

Contents Page
Foreword .iv
1 Scope.1
2 Material.1
3 Specific terms and definitions .2
4 Unwrought products.2
5 Wrought products .2
6 Castings .5
7 Methods of processing and treatment.6
8 Surface condition.8
9 Applications.8
10 Abbreviations for titanium melting methods .9
11 Classification of titanium and titanium alloys.9
11.1 General.9
11.2 Unalloyed titanium.9
11.3 Titanium alloys.9
12 Titanium grades and compounds.10
12.1 Commercially pure titanium (CP titanium).10
12.2 Corrosion-resistance-enhanced grades of CP titanium.10
12.3 Titanium-base intermetallic compounds.10
Annex A (normative) Dividing line between titanium and titanium alloys.11
Annex B (normative) Explanatory notes concerning the definitions of wrought products.12
Alphabetical index.13

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 through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 28401 was prepared by Technical Committee ISO/TC 79, Light metals and their alloys, Subcommittee
SC 11, Titanium.
iv © ISO 2010 – All rights reserved

INTERNATIONAL STANDARD ISO 28401:2010(E)

Light metals and their alloys — Titanium and titanium alloys —
Classification and terminology

1 Scope
This International Standard gives a classification of titanium and titanium alloys. It also gives terms and
definitions in the field of titanium and its alloys.
2 Material
2.1
titanium sponge
products of metallic titanium in porous and sponge-like form, which is applied as titanium metal melting stock
NOTE The oxidized titanium ore is first chlorinated to tetrachloride and is condensed and purified and then reduced with
magnesium or sodium under the inert atmosphere to produce titanium sponge.
2.2
alloy
metallic substance consisting of a mixture of the basic metallic element (the element predomination by mass)
and other elements, such as alloying elements and impurities
2.3
alloying element
metallic or non-metallic elements intentionally added to, or retained by, basic metal for the purpose of giving
that metal certain special properties
2.4
impurity
metallic or non-metallic elements present but which are not intentionally added to, or retained by, a metal
2.5
wrought alloy
alloy primarily intended for the production of wrought products by hot and/or cold plastic forming
2.6
casting alloy
alloy primarily intended for the production of castings
2.7
master alloy
alloy intended only for addition to a melt to adjust composition or to control impurities
2.8
heat-treatable alloy
alloy capable of being strengthened by a suitable thermal treatment
2.9
non-heat-treatable alloy
alloy strengthened by cold working only and incapable of being substantially strengthened by thermal treatment
3 Specific terms and definitions
3.1
intermediate-strength alloys
alloys with improved properties due to a limited percentage of alloying elements enhancing mechanical
resistance and, from case to case, also corrosion resistance
3.2
high-strength standard alloys
alloys with properties similar to the alloy work-horse Ti-6Al-4V (Al ≈ 6 %, V ≈ 4 %), well defined and used with
experience
3.3
special alloy grades
high-strength and highly alloyed grades for special use, for example, in military and space equipment
4 Unwrought products
4.1
unwrought product
general term for products obtained by melting or casting processes
EXAMPLES Ingots for rolling, ingots for extruding, ingots for forging and ingots for remelting.
4.2
electrode for remelting
formed from titanium sponge and alloying elements or consolidated from recycled and processed scrap,
normally to be remelted finally at least once under a vacuum or in argon
4.3
ingot for rolling
titanium ingot in a form suitable for rolling, melted by EB, VAR, VASM or PM methods applied for at least the
final cycle under a vacuum or in argon
4.4
ingot for extruding
titanium ingot in a form suitable for extrusion of bars, tubes and slaps melted by EB, VAR, VASM or PM
methods applied for at least the final cycle under a vacuum or in argon
4.5
ingot for forging
titanium ingot in a form suitable for forging, melted by EB, VAR, VASM or PM methods applied for at least the
final cycle under a vacuum or in argon
4.6
ingot for remelting
titanium ingot in a form suitable for remelting after having been processed metallurgically for composition,
melted by EB, VAR, VASM or PM methods applied for at least the final cycle under a vacuum or in argon
5 Wrought products
5.1
wrought product
general term for products obtained by hot and/or cold plastic deformation processes, such as extruding,
forging, hot rolling, cold rolling or drawing, either solely or in combination
2 © ISO 2010 – All rights reserved

EXAMPLES Rod/bar, billets, wire, tube, shape/profile, sheet, plate, strip, foils, die forgings, open die forgings.
NOTE For the classification principles of wrought products, see Annex B.
5.2
billets
solid wrought product of uniform cross-section that is above 10 000 mm along its whole length, supplied in
straight lengths
NOTE The cross-sections are in the shape of circles, ovals, squares, rectangles, equilateral triangles or regular
polygons. Products with a square, rectangular, triangular or polygonal cross-section may have corners rounded along their
whole length.
5.3
rod/bar
solid wrought product of uniform cross-section that is under 10 000 mm along its whole length, supplied in
straight lengths
NOTE 1 The cross-sections are in the shape of circles, ovals, squares, rectangles, equilateral triangles or regular
polygons. Products with a square, rectangular, triangular or polygonal cross-section may have corners rounded along their
whole length.
NOTE 2 For rectangular bars:
— the thickness exceeds one-third of the width;
— the term “rectangular bar” includes “flattened circles” and “modified rectangles”, of which two opposite sides are
convex arcs, the other two sides being straight, of equal length and parallel.
5.4
wire
solid wrought product of uniform cross-section along its whole length, supplied in coiled form
NOTE 1 The cross-sections are in the shape of circles, ovals, squares, rectangles, equilateral triangles or regular
polygons. Products with a square, rectangular, triangular, or polygonal cross-section may have corners rounded along
their whole length.
NOTE 2 For rectangular wires:
— the thickness exceeds one-third of the width;
— the term “rectangular wire” includes “flattened circles” and “modified rectangles”, of which two opposite sides are
convex arcs, the other two sides being straight, of equal length and parallel.
5.5
drawing stock
intermediate solid wrought product of uniform cross-section along its whole length supplied in coils
NOTE The cross-sections are approximately round, triangular or regular polygonal with dimensions usually exceeding
5 mm.
5.6
tube
hollow wrought product of uniform cross-section with only one enclosed hollow space along its whole length,
and with a uniform wall thickness, supplied in straight lengths or in coiled form
NOTE 1 The cross-sections are in the shape of circles, ovals, squares, rectangles, equilateral triangles or regular
polygons. Hollow products with square, rectangular, equilateral triangular or regular polygonal cross-sections, which may
have corners rounded along their whole length, are also to be considered as tubes, provided the inner and outer
peripheries are concentric and have the same form and orientation.
NOTE 2 Tubes can also be formed by piercing trespassing and by forming and joining sheet or strip.
NOTE 3 Bent, threaded, drilled, waisted, expanded and cone-shaped hollow products in this form, when derived from
tubes as defined above, are classified as tubes.
5.7
profile/shape
wrought product of uniform cross-section along its whole length, with a cross-section other than rod/bar, wire,
tube, sheet, plate or strip, supplied in straight lengths or in coiled form
NOTE According to the form of its cross-section, it is called hollow profile or non-hollow profile.
a) Hollow profile
The cross-section includes:
— either one enclosed hollow space, provided that the cross-section is for other than a tube, or
— more than one enclosed hollow space.
b) Non-hollow profile
The cross-section does not include any enclosed hollow space.
5.8
plate
flat-rolled product of rectangular cross-section with uniform thickness over 5 mm, supplied in straight lengths
(i.e. flat) usually with sheared, sawn or flame-cut/plasma-cut edges or water-jet cutting
NOTE The thickness does not exceed one-tenth of the width.
5.9
sheet
flat-rolled product of rectangular cross-section with uniform thickness over 0,20 mm and up to and including
5 mm, supplied in straight lengths (i.e. flat) usually with sheared or sawn edges or water jet cutting
NOTE The thickness does not exceed one-tenth of the width.
5.10
strip
flat-rolled product of rectangular cross-section with uniform thickness over 0,20 mm, supplied in coils usually
with slit edges
NOTE 1 The thickness does not exceed one-tenth of the width.
NOTE 2 Corrugated, embossed (with patterns, for example, grooves, ribs, checkers, tears, buttons, lozenges), coated,
edge conditioned and perforated products in this general form when derived from strip as defined above are classified as
strip.
NOTE 3 In some English-speaking countries, “strip” is called “coiled sheet”.
5.11
foil
flat-rolled product of rectangular cross-section with uniform thickness equal to or less than 0,20 mm
NOTE In some countries, the term “foil” covers two different products:
— foil: products with lesser thickness;
— thin strip: products with greater thickness.
The dimensional limitations between these two products may vary from country to country.
5.12
forging stock
hot-worked intermediate solid wrought product, for example rod/bar or billets, or any other cross-section,
suitable for forging
NOTE Forging stock may also be a cast product, for example, ingot for forging (see 4.5).
4 © ISO 2010 – All rights reserved

5.13
casting stock
cast or hot-worked intermediate solid wrought product, for example, rod/bar or billets, or any other cross-
section, suitable for casting
5.14
forging
wrought product formed by hammering or pressing, usually when hot, between open dies (hand f
...