ISO 9649:2023

Metallic materials - Wire - Reverse torsion test

This document specifies a method for determining the ability of metallic wire, of diameter dimension from 0,3 mm to 10,0 mm inclusive, to undergo plastic deformation during reverse torsion. This test is used to detect surface defects, as well as to assess ductility.

Matériaux métalliques — Fils — Essai de torsion alternée

General Information

• Status: Published
• Publication Date: 14-May-2023
• ICS: 77.040.10 - Mechanical testing of metals
• Technical Committee: ISO/TC 164/SC 2 - Ductility testing
• Drafting Committee: ISO/TC 164/SC 2 - Ductility testing
• Current Stage: 6060 - International Standard published
• Start Date: 15-May-2023
• Due Date: 11-Oct-2023
• Completion Date: 15-May-2023

Relations

• Revises: ISO 9649:2016 - Metallic materials - Wire - Reverse torsion test
• Effective Date: 06-Jun-2022

Overview

ISO 9649:2023 - Metallic materials - Wire - Reverse torsion test defines a standardized method to determine the ability of metallic wire (diameter 0.3 mm to 10.0 mm inclusive) to undergo plastic deformation under alternating torsion. The reverse torsion test is used primarily to detect surface defects and to assess wire ductility and overall quality. This third edition (2023) updates the 2016 version and clarifies test reporting and certain procedural details.

Keywords: ISO 9649:2023, reverse torsion test, metallic wire testing, wire ductility, surface defect detection, wire quality control.

Key topics and technical requirements

• Scope: Applies to round wires with nominal diameters from 0.3 mm to 10.0 mm for detecting surface defects and assessing ductility.
• Test principle: Twist the specimen a specified number of full turns (360° per turn) in one direction, then the specified number in the opposite direction.
• Test piece preparation:
  • Wire must be as straight as possible; straightening is allowed provided the surface is not damaged and no twisting is introduced.
  • Wires with local kinks or sharp curvature must not be used.
• Free length between grips (L): Specified as a function of nominal diameter (d):
  • 0.3 ≤ d < 1.0 mm: L = 200·d
  • 1.0 ≤ d < 5.0 mm: L = 100·d
  • 5.0 ≤ d ≤ 10.0 mm: L = 50·d
  • Shorter lengths may be agreed by supplier and purchaser (see standard).
• Equipment requirements:
  • Rigid, abrasion‑resistant grips aligned on the same axis; one grip rotates, the other remains fixed (except for torque measurement).
  • Machine must allow axial length change during deformation and permit application of a tensile stress (up to 2% of nominal tensile strength when used to keep specimen straight).
  • Adjustable rotation speed and turn-count recording; protective shield to contain fragments if wire fails.
• Test conditions: Ambient 10 °C–35 °C (or controlled 23 ± 5 °C where required).
• Operating parameters:
  • Rotation speed ≤ 1 turn/s (≤ 0.5 turn/s for d ≥ 5 mm).
  • Number of turns in each direction (N1, N2) are specified in the relevant product or sector standards.
• Acceptance and validity: Visual examination for surface defects, cracks, configuration and failure. If failure occurs within 2·d of the grip before reaching required N, the test is invalid and must be repeated.
• Reporting: The standard specifies required test report items (reference to ISO 9649, material ID, diameter, preparation, test conditions, N1/N2, and visual results).

Applications and users

• Practical uses: incoming quality control, production testing, material qualification, failure analysis and R&D for wire products.
• Typical users: wire manufacturers, spring and fastener producers, quality assurance laboratories, material testing labs, and end‑users requiring wire ductility and surface integrity verification.
• Industries: automotive, aerospace, construction, electronics, springs and fasteners, and any sector relying on high‑quality metallic wire.

Related standards

• ISO 8458-3 referenced as an example application (steel wire for mechanical springs).
• ISO/TC 164 (Mechanical testing of metals) provides the technical committee context.

This concise summary helps procurement, QA teams, and test laboratories implement ISO 9649:2023 for consistent reverse torsion testing and reliable detection of surface defects and ductility characteristics in metallic wire.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 9649
Third edition
2023-05
Metallic materials — Wire — Reverse
torsion test
Matériaux métalliques — Fils — Essai de torsion alternée
Reference number
© ISO 2023
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
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and designations . 1
5 Principle . 2
6 Testing equipment . 2
7 Test piece . 2
8 Test conditions .3
9 Procedure .3
10 Test report . 3
Bibliography . 4
iii
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 third edition cancels and replaces the second edition (ISO 9649:2016), which has been technically
revised.
The main changes are as follows:
— a specification has been added at the end of 9.2;
— a specification has been added at the end of Clause 10 [See g)].
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.
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