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
Withdrawn
Publication Date
30-Jan-2021
Withdrawal Date
29-Apr-2021
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Start Date
21-Oct-2020
Completion Date
21-Oct-2020

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SLOVENSKI STANDARD
SIST EN ISO 7438:2021
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
SIST EN ISO 7438:2021 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 7438:2021
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SIST EN ISO 7438:2021
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.
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SIST EN ISO 7438:2021
EN ISO 7438:2020 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 7438:2021
EN ISO 7438:2020 (E)
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.

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SIST EN ISO 7438:2021
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SIST EN ISO 7438:2021
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
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SIST EN ISO 7438:2021
ISO 7438:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© 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: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
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SIST EN ISO 7438:2021
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 2020 – All rights reserved iii
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SIST EN ISO 7438:2021
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
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SIST EN ISO 7438:2021
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 —
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 2020 – All rights reserved 1
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SIST EN ISO 7438:2021
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
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SIST EN ISO 7438:2021
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
...

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