prEN ISO 7799
(Main)Metallic materials - Sheet and strip 3 mm thick or less - Reverse bend test (ISO/DIS 7799:2026)
- Abstract
Specifies the method for determining the ability of sheet and strip to undergo plastic deformation in reverse bending. Can be applied to aluminium and its alloys only after previous agreement. The reverse bend test consists of repeated bending through 90 , in opposite directions, of a rectangular test piece held at one end, each bend being over a cylindrical support of specified radius.
- Status
- Not Published
- Publication Date
- 18-Oct-2027
- Technical Committee
- ECISS/TC 101 - Test methods for steel (other than chemical analysis)
- Current Stage
- 4060 - Closure of enquiry - Enquiry
- Start Date
- 21-Jul-2026
- Completion Date
- 21-Jul-2026
prEN ISO 7799 is a CEN draft standard for the reverse bend test on metallic sheet and strip 3 mm thick or less. It specifies a method for checking how these products undergo plastic deformation when bent repeatedly through 90° in opposite directions over a cylindrical support. The method is used by engineers, test laboratories, quality teams and product specifiers who need a consistent ductility test for sheet and strip.
What does prEN ISO 7799 specify?
prEN ISO 7799 specifies the reverse bend test for metallic sheet and strip 3 mm thick or less. It also states that the method can be used for aluminium and its alloys only after previous agreement, so parties need to confirm applicability before using it for those materials.
The document is organized into clauses on scope, normative references, terms and definitions, symbols and designations, principle, testing equipment, test piece, procedure and test report, followed by one informative annex and a bibliography.
| Annex | What it covers |
|---|---|
| Annex A (informative) | Examples of devices that apply force to test pieces during the reverse bend test |
What are the key requirements of prEN ISO 7799?
prEN ISO 7799 defines a controlled bending method, the equipment geometry, specimen preparation, test conditions and reporting items. In practice, these clauses are what make results comparable between laboratories and between batches of material.
- Clause 5 - Principle: The test piece is bent through 90° in opposite directions, repeatedly, over a cylindrical support. This gives a direct check on how well the material tolerates reverse plastic deformation before fracture or cracking.
- Clause 6 and Table 2 - Equipment geometry: The testing machine has to match the stated layout, including support radius, guide slit width, and distances linked to specimen thickness. This matters because the bend severity depends on geometry.
- Clause 6.2 - Supports and gripping faces: The cylindrical supports and gripping faces must be harder than the test piece, aligned within the stated limits, and positioned to avoid excessive clearance. That helps prevent abrasion and misalignment from influencing the result.
- Clause 6.3 - Bending arm and guide: The pivoting axis, guide slit and distance from the supports are controlled by the standard. This keeps the bend path consistent from one test to another.
- Clause 7 - Test piece: The test piece keeps the original thickness, usually has a width between 20 mm and 25 mm, and a length of at least 150 mm, with clean surfaces and burr-free edges. This means the specimen should represent the product without damage from preparation.
- Clause 8 - Procedure: Testing is normally done at ambient temperature between 10 °C and 35 °C, or at 23 °C ± 5 °C under controlled conditions, and the bending rate must not exceed one bend per second. If heat from the test could affect the result, the rate is reduced.
- Clause 8.4 and 8.5 - Force and end point: A tensile force may be used to keep the test piece in contact with the supports, but it is limited unless otherwise agreed. The test ends when the specified number of bends is reached or the piece fractures, and visible cracking without magnification can be used only when the relevant standard asks for it.
- Clause 9 - Test report: The report records the reference to the document, date, specimen identification and orientation, specimen size, test conditions, end criterion, deviations and the result. In practice, this is the evidence trail for acceptance, comparison or dispute.
What terms does prEN ISO 7799 define?
prEN ISO 7799 uses these key terms and symbols in the test method:
- reverse bend test - repeated 90° bending in opposite directions of a rectangular test piece held at one end.
- test piece - the specimen cut from the sheet or strip and used in the test.
- cylindrical supports - the rounded supports that set the bending radius.
- gripping faces - the clamping faces that hold the lower end of the test piece.
- bending arm - the part that moves the free end through the repeated bends.
- guide - the slotted part that keeps the specimen aligned during bending.
- N_b - the number of reverse bends recorded as the test result.
- F - the applied tension force used to maintain contact between the test piece and the supports.
Who uses prEN ISO 7799?
prEN ISO 7799 is used by mechanical testing laboratories, metal producers, quality control teams and product specifiers for sheet and strip. It is useful when a contract, product specification or internal control plan needs a repeatable bend test for ductility or formability.
It also matters for buyers and suppliers who need to agree how the material will be checked before acceptance. The standard gives them a common test setup, common specimen preparation and a common way to report results.
What changed in prEN ISO 7799 from the previous edition?
prEN ISO 7799 replaces ISO 7799:1985 and the draft says it is technically revised. The stated changes are:
- symbols for applied tension, test piece width and guide slit width were added in Table 1
- Table 2 was adjusted to include the limits for distance L and guide slit width w
- the test piece length was modified for easier application
- the tensile force requirements were updated
- the test-ending criterion was changed for easier application
- Annex A was added with examples of devices that apply force to test pieces
- the structure was updated to match the current ISO/IEC Directives, Part 2
What does the prEN ISO 7799 document contain?
prEN ISO 7799 contains a symbol table, a test principle figure, detailed equipment requirements, specimen preparation rules, a step-by-step test procedure and a test report checklist. Table 1 gives the symbols and designations used throughout the method, and Table 2 gives the key dimensions and tolerances by specimen thickness.
Figures 1 and 2 show the test arrangement and the bend counting method. Annex A gives two example force-applying devices, one using a spring and one using weights, for situations where continuous contact with the supports must be maintained.
The bibliography lists related documents, including ISO 24259, ASTM A720/A720M-02 and IEC/TR 63114, for readers who need broader context on ductility and reverse bend testing.
Relations
- Effective Date
- 17-Jul-2024
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Frequently Asked Questions
prEN ISO 7799 is a draft published by the European Committee for Standardization (CEN). Its full title is "Metallic materials - Sheet and strip 3 mm thick or less - Reverse bend test (ISO/DIS 7799:2026)". This standard covers: Specifies the method for determining the ability of sheet and strip to undergo plastic deformation in reverse bending. Can be applied to aluminium and its alloys only after previous agreement. The reverse bend test consists of repeated bending through 90 , in opposite directions, of a rectangular test piece held at one end, each bend being over a cylindrical support of specified radius.
Specifies the method for determining the ability of sheet and strip to undergo plastic deformation in reverse bending. Can be applied to aluminium and its alloys only after previous agreement. The reverse bend test consists of repeated bending through 90 , in opposite directions, of a rectangular test piece held at one end, each bend being over a cylindrical support of specified radius.
prEN ISO 7799 is classified under the following ICS (International Classification for Standards) categories: 77.040.10 - Mechanical testing of metals. The ICS classification helps identify the subject area and facilitates finding related standards.
prEN ISO 7799 has the following relationships with other standards: It is inter standard links to EN ISO 7799:2000. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
prEN ISO 7799 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
SLOVENSKI STANDARD
01-julij-2026
Kovinski materiali - Plošče in trakovi debeline 3 mm ali manj - Preskus upogibanja
v nasprotni smeri (ISO/DIS 7799:2026)
Metallic materials - Sheet and strip 3 mm thick or less - Reverse bend test (ISO/DIS
7799:2026)
Metallische Werkstoffe - Bleche und Bänder mit einer Dicke unter 3 mm - Hin- und
Herbiegeversuch (ISO/DIS 7799:2026)
Matériaux métalliques - Tôles et feuillards d'épaisseur inférieure ou égale à 3 mm - Essai
de pliage alterné (ISO/DIS 7799:2026)
Ta slovenski standard je istoveten z: prEN ISO 7799
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.
DRAFT
International
Standard
ISO/DIS 7799
ISO/TC 164/SC 2
Metallic materials — Sheet and strip
Secretariat: JISC
3 mm thick or less — Reverse bend
Voting begins on:
test
2026-04-28
Matériaux métalliques — Tôles et feuillards d'épaisseur
Voting terminates on:
inférieure ou égale à 3 mm — Essai de pliage alterné
2026-07-21
ICS: 77.040.10
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS.
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Reference number
ISO/DIS 7799:2026(en)
DRAFT
ISO/DIS 7799:2026(en)
International
Standard
ISO/DIS 7799
ISO/TC 164/SC 2
Metallic materials — Sheet and strip
Secretariat: JISC
3 mm thick or less — Reverse bend
Voting begins on:
test
Matériaux métalliques — Tôles et feuillards d'épaisseur
Voting terminates on:
inférieure ou égale à 3 mm — Essai de pliage alterné
ICS: 77.040.10
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2026
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
BE CONSIDERED IN THE LIGHT OF THEIR
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
or ISO’s member body in the country of the requester.
NATIONAL REGULATIONS.
ISO copyright office
RECIPIENTS OF THIS DRAFT ARE INVITED
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TO SUBMIT, WITH THEIR COMMENTS,
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NOTIFICATION OF ANY RELEVANT PATENT
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PROVIDE SUPPORTING DOCUMENTATION.
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Website: www.iso.org
Published in Switzerland Reference number
ISO/DIS 7799:2026(en)
ii
ISO/DIS 7799:2026(en)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and designations . 1
5 Principle . 1
6 Testing equipment . 2
6.1 General .2
6.2 Cylindrical supports and gripping faces .3
6.3 Bending arm and guide .3
7 Test piece . 3
8 Procedure . 4
9 Test report . 5
Annex A (informative) Examples of some devices applying force to test pieces . 6
Bibliography . 8
iii
ISO/DIS 7799:2026(en)
Foreword
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This document was prepared by Technical Committee ISO/TC 164, Mechanical testing of metals, Subcommittee
SC 2, Ductility testing.
This second edition cancels and replaces the first edition (ISO 7799:1985), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— symbols for applied tension, F, width of test piece, b and width of slit of the guide, w have been added in
Table 1;
— Table 2 has been adjusted to include the limits of the distance, L, from the top tangential plane of
cylindrical supports to the bottom face of the guide, and the width of the slit of the guide, w;
— the test piece length has been modified for ease of application;
— the requirements for t
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