EN ISO 7438:2020

Metallic materials - Bend test (ISO 7438:2020)

This document specifies a method for determining the ability of metallic materials to undergo plastic deformation in bending.
This document applies to test pieces taken from metallic products, as specified in the relevant product standard. It is not applicable to certain materials or products, for example tubes in full section or welded joints, for which other standards exist.

Metallische Werkstoffe - Biegeversuch (ISO 7438:2020)

Dieses Dokument legt ein Verfahren zur Bestimmung der plastischen Verformbarkeit metallischer Werkstoffe im Biegeversuch fest.
Dieses Dokument wird angewendet für Proben, die von metallischen Erzeugnissen nach entsprechenden Werkstoffnormen entnommen werden. Es ist nicht anwendbar auf spezielle Werkstoffe oder Erzeugnisse, z. B. Rohrabschnitte, Schweißverbindungen, für die es andere Normen gibt.

Matériaux métalliques - Essai de pliage (ISO 7438:2020)

Le présent document spécifie une méthode de détermination de l'aptitude à la déformation plastique par pliage des matériaux métalliques.
Le présent document est applicable aux éprouvettes prélevées dans des produits métalliques tels que spécifiés dans la norme de produit pertinente. Elle n'est pas applicable à certains matériaux ou produits, par exemple tubes en section complète ou assemblages soudés pour lesquels d'autres normes existent.

Kovinski materiali - Upogibni preskus (ISO 7438:2020)

General Information

• Status: Published
• Publication Date: 20-Oct-2020
• Withdrawal Date: 29-Apr-2021
• ICS: 77.040.10 - Mechanical testing of metals
• Technical Committee: ECISS/TC 101 - Test methods for steel (other than chemical analysis)
• Drafting Committee: ECISS/TC 101 - Test methods for steel (other than chemical analysis)
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 21-Oct-2020
• Completion Date: 21-Oct-2020
• Ref Project: SIST EN ISO 7438:2021 - Metallic materials - Bend test (ISO 7438:2020)

Relations

• Replaces: EN ISO 7438:2016 - Metallic materials - Bend test (ISO 7438:2016)
• Effective Date: 08-Jun-2022

Overview

EN ISO 7438:2020 - Metallic materials - Bend test (ISO 7438:2020) is the international / European method for assessing the ability of metallic materials to undergo plastic deformation by bending. Prepared by ISO/TC 164 and adopted by CEN, this fourth edition (2020) supersedes EN ISO 7438:2016 and adds an informative Annex B describing bend testing under plane strain conditions. The standard applies to test pieces taken from metallic products (round, square, rectangular or polygonal cross-sections) unless a product-specific standard or another test (e.g., for full-section tubes or welded joints) applies.

Key topics and requirements

• Scope & purpose: Defines a reproducible bend test to evaluate ductility and bending performance of metallic materials.
• Test pieces: Specifies permitted cross-section shapes and preparation. Areas affected by shearing or flame cutting should normally be removed; edges of rectangular pieces must be rounded (3 mm for thickness ≥50 mm; 1.5 mm for 10–<50 mm; 1 mm for thickness <10 mm).
• Test equipment: Describes three bending device types - two supports with a former, V-block with a former, and clamp with a former - and requires sufficient hardness of supports/former. The standard sets geometric relationships (former diameter, support spacing) that govern test setup; support distance must remain constant during testing.
• Test parameters & symbols: Defines key symbols and parameters (thickness a, width b, former diameter D, displacement f, bend angle α, support spacing l, etc.) used to control and report the test.
• Procedure & interpretation: Outlines the bending procedure (apply bending without changing load direction until specified angle) and how to record/interpret outcomes per product requirements. Annex B provides criteria for plane strain bending tests.
• Reporting: Requires documented test reports with geometry, equipment, conditions and results.

Practical applications

• Quality control and incoming inspection for steels and other metals.
• Material qualification during product development or manufacturing (forging, casting, rolled products).
• Conformance testing required by product standards that reference bend testing for ductility/fit-for-purpose assessment.
• Used by testing laboratories, material engineers, manufacturers, inspection bodies, and certification organizations.

Who should use this standard

• Mechanical testing laboratories and metallurgical laboratories
• Steel, aluminum and non‑ferrous product manufacturers and fabricators
• Quality assurance engineers, R&D teams, and compliance/accountability departments
• Standards bodies and product-specification authors

Related standards

• Product-specific standards that reference ISO 7438 for sampling and required bend criteria (consult the relevant product standard).
• Other ductility or mechanical test standards (e.g., bend tests for welded joints or full-section tubes, which are excluded from this document).

Keywords: EN ISO 7438:2020, bend test, metallic materials, bend testing, bending device, plane strain, mechanical testing of metals, test pieces, CEN, ISO 7438.

Standards Content (Sample)

SLOVENSKI STANDARD
01-marec-2021
Nadomešča:
SIST EN ISO 7438:2016
Kovinski materiali - Upogibni preskus (ISO 7438:2020)
Metallic materials - Bend test (ISO 7438:2020)
Metallische Werkstoffe - Biegeversuch (ISO 7438:2020)
Matériaux métalliques - Essai de pliage (ISO 7438:2020)
Ta slovenski standard je istoveten z: EN ISO 7438:2020
ICS:
77.040.10 Mehansko preskušanje kovin Mechanical testing of metals
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 7438
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2020
EUROPÄISCHE NORM
ICS 77.040.10 Supersedes EN ISO 7438:2016
English Version
Metallic materials - Bend test (ISO 7438:2020)
Matériaux métalliques - Essai de pliage (ISO Metallische Werkstoffe - Biegeversuch (ISO
7438:2020) 7438:2020)
This European Standard was approved by CEN on 8 August 2020.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 7438:2020 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 7438:2020) has been prepared by Technical Committee ISO/TC 164
"Mechanical testing of metals" in collaboration with Technical Committee CEN/TC 459/SC 1 “Test
methods for steel (other than chemical analysis)” the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by April 2021, and conflicting national standards shall be
withdrawn at the latest by April 2021.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 7438:2016.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 7438:2020 has been approved by CEN as EN ISO 7438:2020 without any modification.

INTERNATIONAL ISO
STANDARD 7438
Fourth edition
2020-10
Metallic materials — Bend test
Matériaux métalliques — Essai de pliage
Reference number
ISO 7438:2020(E)
©
ISO 2020
ISO 7438:2020(E)
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved

ISO 7438:2020(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols, designations and units . 1
5 Principle . 2
6 Test equipment. 2
6.1 General . 2
6.2 Bending device with supports and a former . 4
6.3 Bending device with a V-block. 4
6.4 Bending device with a clamp . 4
7 Test piece . 4
7.1 General . 4
7.2 Edges of rectangular test pieces. 4
7.3 Width of the test piece . 5
7.4 Thickness of the test piece . 5
7.5 Test pieces from forgings, castings and semi-finished products . 5
7.6 Agreement for test pieces of greater thickness and width . 5
7.7 Length of the test piece . 5
8 Procedure. 6
9 Interpretation of results . 7
10 Test report . 7
Annex A (informative) Determination of the bend angle from the measurement of the
displacement of the former . 8
Annex B (normative) Bend test at plane strain conditions . 9
Bibliography .13
ISO 7438:2020(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
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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 164, Mechanical testing of metals,
Subcommittee SC 2, Ductility testing, in collaboration with the European Committee for Standardization
(CEN) Technical Committee CEN/TC 459, ECISS – European Committee for Iron and Steel Standardization,
in accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This fourth edition cancels and replaces the third edition (ISO 7438:2016), which has been technically
revised.
The main change compared to the previous edition is the addition of new Annex B, describing bending
test at plane strain condition.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved

INTERNATIONAL STANDARD ISO 7438:2020(E)
Metallic materials — Bend test
1 Scope
This document specifies a method for determining the ability of metallic materials to undergo plastic
deformation in bending.
This document applies to test pieces taken from metallic products, as specified in the relevant product
standard. It is not applicable to certain materials or products, for example tubes in full section or
welded joints, for which other standards exist.
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 databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at https:// www .iso .org/ obp
4 Symbols, designations and units
Symbols and designations used in the bend test are shown in Figures 1 and 2 and specified in Table 1.
Table 1 — Symbols, designations and units
Symbol Designation Unit
a Thickness or diameter of test piece (or diameter of the inscribed circle mm
for pieces of polygonal cross-section)
b Width of the test piece mm
c Distance between the plane including the horizontal axis of supports mm
and the central axis of the rounded portion of the former before test
D Diameter of the former mm
f Displacement of the former mm
Lode angle parameter, i.e. strain path direction —
θ
L Length of the test piece mm
l Distance between supports mm
η Triaxiality factor —
p Distance between the vertical planes including the central axis of each mm
support and the vertical plane including the central axis of the former
R Radius of the supports mm
r Internal radius of bend portion of test piece after bending mm
α Angle of bend degrees
ISO 7438:2020(E)
5 Principle
The bend test consists of submitting a test piece of round, square, rectangular or polygonal cross-
section to plastic deformation by bending, without changing the direction of loading, until a specified
angle of bend is reached.
The axes of two legs of the test piece remain in a plane perpendicular to the axis of bending. In the case
of a 180° bend, the two lateral surfaces may, depending on the requirements of the product standard,
lie flat against each other or can be parallel at a specified distance, an insert being used to control this
distance.
6 Test equipment
6.1 General
The bend test shall be carried out in testing machines or presses equipped with the following devices:
a) bending device with two supports and a former as shown in Figure 1;
b) bending device with a V-block and a former as shown in Figure 2;
c) bending device with a clamp as shown in Figure 3.
Figure 1 — Bending device with two supports and a former
2 © ISO 2020 – All rights reserved

ISO 7438:2020(E)
Figure 2 — Bending device with a V-block and a former
Key
1 clamp
2 former
Figure 3 — Bending device wi
...