ISO 16120-1:2017

INTERNATIONAL ISO
STANDARD 16120-1
Third edition
2017-05
Non-alloy steel wire rod for
conversion to wire —
Part 1:
General requirements
Fil-machine en acier non allié destiné à la fabrication de fils —
Partie 1: Exigences générales
Reference number
ISO 16120-1:2017(E)
©
ISO 2017

---------------------- Page: 1 ----------------------
ISO 16120-1:2017(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, 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
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 16120-1:2017(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Classification . 3
5 Ordering information to be supplied by the purchaser. 3
6 Production process . 4
7 Requirements . 4
7.1 General . 4
7.2 Quality system . 4
7.3 Method of delivery . 4
7.4 Delivery condition . 5
8 Dimensions, mass and tolerances . 5
9 Inspection . 5
9.1 Inspection and inspection documents . 5
9.2 Extension of inspection . 5
9.3 Acceptance unit, number of samples and test pieces . 5
9.4 Sampling and preparation of samples and test pieces . 6
9.4.1 Chemical composition . 6
9.4.2 Tensile strength . 6
9.4.3 Decarburization, surface discontinuities, non-metallic inclusions, core
segregation and microstructure . 6
9.5 Test methods . 6
9.5.1 Chemical composition . 6
9.5.2 Tensile strength . 6
9.5.3 Surface discontinuities . 6
9.5.4 Decarburization . 7
9.5.5 Non-metallic inclusions . 7
9.5.6 Core segregation . 7
9.5.7 Microstructure . 7
9.5.8 Determination of cementite network in high-carbon steel wire rod . . 7
9.6 Retest . 7
10 Marking . 7
11 Disputes . 7
Annex A (normative) Determination of core segregation . 8
Annex B (informative) Measurement of surface discontinuities .11
Annex C (informative) Mechanical damage .14
Annex D (normative) Determination of percentage of resolvable pearlite in high-carbon
steel wire rod .18
Annex E (normative) Determination of cementite network in high-carbon steel wire rod .22
Bibliography .27
© ISO 2017 – All rights reserved iii

---------------------- Page: 3 ----------------------
ISO 16120-1:2017(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 on 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 the following
URL: w w w . i s o .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 17, Steel, Subcommittee SC 17, Steel wire
rod and wire products.
This third edition cancels and replaces the second edition (ISO 16120-1:2011), which has been
technically revised.
The main changes compared to the previous edition are:
— core segregation, surface discontinuity and mechanical damage have been added to the terms and
definitions;
— determination of cementite network in high-carbon steel wire rod (9.5.8 and Annex E) added.
A list of all parts in the ISO 16120 series can be found on the ISO website.
iv © ISO 2017 – All rights reserved

---------------------- Page: 4 ----------------------
INTERNATIONAL STANDARD ISO 16120-1:2017(E)
Non-alloy steel wire rod for conversion to wire —
Part 1:
General requirements
1 Scope
The ISO 16120 series is applicable to wire rod of non-alloy steel intended for wire drawing and/or cold
rolling. The cross-section can be circular, oval, square, rectangular, hexagonal, octagonal, half-round or
another shape, generally with at least 5 mm nominal dimension, and with a smooth surface.
This document specifies general requirements for non-alloy steel wire rod for conversion to wire. It is
not applicable to products for which standards exist or are in development, for example:
— steel wire rod intended for heat treatment;
— free-cutting steel wire rod;
— steel wire rod for cold heading and cold extrusion;
— steel wire rod intended for the production of electrodes and products for welding;
— steel wire rod for welded fabric for reinforcement for concrete;
— steel wire rod for ball and roller bearings (see ISO 683-17);
— steel wire rod for wire for high fatigue strength mechanical springs, such as valve springs.
In addition to the requirements of this document, the general technical delivery requirements specified
in ISO 404 apply.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 377, Steel and steel products — Location and preparation of samples and test pieces for mechanical testing
ISO 404:2013, Steel and steel products — General technical delivery requirements
ISO 3887, Steels — Determination of depth of decarburization
ISO 4885, Ferrous products — Heat treatments — Vocabulary
ISO 4948-1, Steels — Classification — Part 1: Classification of steels into unalloyed and alloy steels based
on chemical composition
ISO 4948-2, Steels — Classification — Part 2: Classification of unalloyed and alloy steels according to main
quality classes and main property or application characteristics
ISO 6892-1, Metallic materials — Tensile testing — Part 1: Method of test at room temperature
ISO 6929, Steel products — Vocabulary
ISO/TR 9769, Steel and iron — Review of available methods of analysis
© ISO 2017 – All rights reserved 1

---------------------- Page: 5 ----------------------
ISO 16120-1:2017(E)

ISO 10474, Steel and steel products — Inspection documents
ISO 14284, Steel and iron — Sampling and preparation of samples for the determination of chemical
composition
ISO 16120-2:2017, Non-alloy steel wire rod for conversion to wire — Part 2: Specific requirements for
general-purpose wire rod
ISO 16120-3:2011, Non-alloy steel wire rod for conversion to wire — Part 3: Specific requirements for
rimmed and rimmed substitute, low-carbon steel wire rod
ISO 16120-4:2017, Non-alloy steel wire rod for conversion to wire — Part 4: Specific requirements for wire
rod for special applications
ISO 16124, Steel wire rod — Dimensions and tolerances
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 377, ISO 404, ISO 4885,
ISO 4948-1, ISO 4948-2 and ISO 6929 and the following apply.
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 http:// www .iso .org/ obp
3.1
rod
hot-rolled finished product hot-wound into irregular coils
Note 1 to entry: Rod used for wire-drawing purposes in coil form is generally termed wire rod.
3.2
heat analysis
chemical analysis representative of the heat, by a method determined at the steelmaker’s discretion
[SOURCE: ISO 404:2013, 3.11, modified.]
3.3
product analysis
chemical analysis carried out on a sample of the product taken after the final hot rolling operation
[SOURCE: ISO 404:2013, 3.12, modified.]
3.4
resolvable pearlite
two-phased structure in which ferrite and iron carbide lamellae can be clearly observed under optical
microscopy in certain conditions
3.5
core segregation
local variation in chemical composition that is noticeable over a cross-section of wire rod (3.1) by
macrographic examination and that concerns primarily the segregation resulting from a solidification
process in continuous casting
Note 1 to entry: It is for this reason that an examination, specifically for carbon core segregation, will reveal the
presence of segregation.
Note 2 to entry: A different technique is used to assess grain boundary cementite (which may be detrimental to
further processing), the formation of which is related to carbon segregation and the cooling rate after wire rod
rolling. However, grain boundary cementite should not be confused with core segregation.
2 © ISO 2017 – All rights reserved

---------------------- Page: 6 ----------------------
ISO 16120-1:2017(E)

3.6
surface discontinuity
measurable discontinuity in the surface of the wire rod (3.1), introduced at some point during the
manufacturing process
3.7
mechanical damage
discernible contact which the wire rod (3.1) encounters after the rolling and coiling operation, i.e.
during subsequent handling of the coil, and which marks the surface
Note 1 to entry: The contact can be introduced by abrasion or impact and can occur between coils or between the
coil and any other material capable of inducing damage (concrete, steel or other materials).
Note 2 to entry: See Annex C.
4 Classification
The classification of the steel grades covered by this document is indicated in ISO 16120-2, ISO 16120-3
and ISO 16120-4 for the corresponding steel grades.
5 Ordering information to be supplied by the purchaser
The following information shall be supplied by the purchaser at the time of enquiry and order, to enable
the supplier to comply satisfactorily with the requirements of the ISO 16120 series:
a) quantity to be delivered;
b) cross-section and product type (e.g. round wire rod, square wire rod, hexagonal wire rod, etc.);
c) nominal dimensions of the wire rod and tolerance class in accordance with ISO 16124 (if another
tolerance class such as T1 is required);
d) reference to the relevant part of ISO 16120, i.e. ISO 16120-2;
e) steel grade, including any variations, and/or the addition of other elements, as permitted by
ISO 16120-2 and ISO 16120-4;
(For steels according to ISO 16120-2 and ISO 16120-4, wire rod can also be ordered by the mean
tensile strength; see ISO 16120-2:2017, Clause 3 and 4.6 and ISO 16120-4:2017, Clause 3 and 4.8.
When ordering to tensile strength, it is necessary also to indicate the required tolerances on tensile
strength ranges — Option A or Option B.)
f) type of inspection and inspection document in accordance with ISO 10474 (or in accordance with
other regional standards, e.g. EN 10204);
g) surface condition (where different from the as-rolled condition);
h) dimensions and mass of coils;
i) where applicable, indication of the type of descaling (chemical cleaning or mechanical);
j) where applicable, the amount of microalloying elements (see ISO 16120-2 and ISO 16120-4);
k) where applicable, class B for the depth of decarburization (see ISO 16120-4);
NOTE If nothing is mentioned in the order, class A will be delivered;
l) where applicable, the microstructure (see ISO 16120-4:2017, 4.11);
m) where applicable, suitability for galvanizing;
n) where applicable, suitability for direct drawing;
© ISO 2017 – All rights reserved 3

---------------------- Page: 7 ----------------------
ISO 16120-1:2017(E)

o) where applicable, the quality system (see 7.2);
p) where applicable, the method of binding and labelling.
Items g) to p) are options. If the purchaser does not indicate a wish to implement any of these options,
the supplier shall supply the product in accordance with the basic specifications of items a) to f).
Examples 1 and 2 provide two ordering examples.
EXAMPLE 1 For grades ordered according to chemical composition, 100 tonnes of round wire rod, nominal
diameter of 12 mm with dimensional tolerances according to ISO 16124, class T1, steel grades ISO 16120-2 –
C52D in the as-rolled condition with an inspection document 3.1 according to ISO 10474.
100 t round wire rod ISO 16124-12,0T1
ISO 16120-2 – C52D
ISO 10474 inspection document 3.1
EXAMPLE 2 For grades ordered according to tensile strength, 200 tonnes of round wire rod, nominal diameter
of 5,5 mm with dimensional tolerances according to ISO 16124, class T1, steel grades ISO 16120-4 – C##D2 with
tensile strength 1 020 MPa, tensile strength tolerance Option A, in the as-rolled condition with an inspection
document 3.1 according to ISO 10474.
200 t round wire rod ISO 16124-5, 5T1
ISO 16120-4 – C##D2–1020A
ISO 10474 inspection document 3.1
NOTE The symbol “##” means “to be left blank” since the carbon content is at the discretion of the supplying
mill, and the supplying mill indicates the exact number of ## based on the grade designation until shipment.
See ISO 16120-2:2017, Table 1 and ISO 16120-4:2017, Table 1, respectively, for the grade designation.
6 Production process
At the request of the purchaser at the time of enquiry and ordering, the steel making and manufacturing
process shall be made known to the purchaser. Those processes that are specifically agreed upon shall
not be changed without the prior agreement of the purchaser.
7 Requirements
7.1 General
Suppliers are responsible, using the means they think fit, for inspecting their product in accordance
with various quality criteria specified. In view of the practical difficulties in inspecting a coil of wire
rod along its entire length, it cannot be proved that no value greater than the specified limits is to be
found in the coil as a whole. Statistical evaluation of performances applicable to all coils may be agreed
between the purchaser and the manufacturer at the time of ordering.
7.2 Quality system
If agreed between the supplier and purchaser at the time of enquiry and order, the wire rod supplied
shall be produced under a mutually acceptable quality system.
7.3 Method of delivery
Wire rod shall be delivered by heat or part of a heat. Unless otherwise specified, the number of heats
per delivery should be minimized as far as possible.
4 © ISO 2017 – All rights reserved

---------------------- Page: 8 ----------------------
ISO 16120-1:2017(E)

7.4 Delivery condition
Wire rod shall be supplied in the as-rolled state, in coils of one continuous length with non-aligned
turns, but capable of being unwound in a regular manner during subsequent processing.
The coils shall be cut back at both ends to provide a product of uniform shape and properties.
8 Dimensions, mass and tolerances
The dimensions, mass and tolerances of the wire rod shall be in accordance with the requirements of
ISO 16124.
9 Inspection
9.1 Inspection and inspection documents
Inspection and inspection documents shall be in accordance with ISO 404 and ISO 10474.
9.2 Extension of inspection
If the order is accompanied by a request for an inspection certificate or an inspection report, the
inspection shall be carried out in accordance with Table 1. If the order requires an inspection document
3.1 or 3.2, the purchaser shall supply to the manufacturer the name and address of the organization or
person nominated to carry out the inspection.
Table 1 — Extension of inspection
Rimmed and
General-purpose Wire rod for
rimmed substitute,
wire rod special applications
Subject of test
low-carbon wire rod
(ISO 16120-2) (ISO 16120-4)
(ISO 16120-3)
Surface discontinuities 0 0 0
Decarburization — — 0
Non-metallic inclusions — 0 0
Core segregation 0 — 0
Product analysis 0 0 0
Tensile strength 0 0 0
a
Microstructure — — 0
a
See Annex D.
— is not carried out.
0 is carried out only if part of the options agreed at the time of ordering.
9.3 Acceptance unit, number of samples and test pieces
Unless otherwise agreed, the acceptance unit is composed of wire rod of the same cross-sectional
dimension, originating from the same heat, and rolled in the same continuous lot.
If specific inspection is required, the number of samples and test pieces given in Table 2 shall apply.
For wire rod for special applications, a higher frequency of sampling may be agreed. If non-specific
inspection is required, the performance statistics or suitable data may be used.
© ISO 2017 – All rights reserved 5

---------------------- Page: 9 ----------------------
ISO 16120-1:2017(E)

Table 2 — Acceptance unit, number of samples and test pieces
Type of requirement Number of samples and test pieces
Product analysis Three, from three different coils originating from
the same heat, but not necessarily rolled in the same
a
continuous lot
Permissible depth of surface discontinuities
Permissible depth of decarburization
One per 20 t with a minimum of three and a maximum
Non-metallic inclusions
a
of five per acceptance unit
Tensile strength
Microstructure
b
Core segregation 10
Cementite network At least 10 samples
a
Another number of samples to be examined may be agreed upon between the supplier and purchaser at the time of
ordering, depending upon the process capability.
b
The number of samples to be examined may be agreed upon between the supplier and the purchaser, with preferably a
minimum of 10.
9.4 Sampling and preparation of samples and test pieces
9.4.1 Chemical composition
Where it has been agreed to verify the chemical composition of the product, sampling and preparation
of samples for heat analysis shall be carried out in accordance with ISO 14284.
9.4.2 Tensile strength
If it is agreed to perform the tensile test, samples shall be taken and prepared in accordance with
ISO 377.
9.4.3 Decarburization, surface discontinuities, non-metallic inclusions, core segregation and
microstructure
For testing for decarburization, surface discontinuities, non-metallic inclusions, core segregation and
microstructure, the required number of test pieces shall be taken from one end of individual cropped
coils (see 7.4).
9.5 Test methods
9.5.1 Chemical composition
The methods for heat analysis shall be in accordance with ISO/TR 9769. The methods to be applied for the
verification of the product analysis shall be agreed upon at the time of ordering. In case of dispute about
analytical methods, the chemical composition shall be determined in accordance with a reference method.
9.5.2 Tensile strength
The tensile test shall be carried out on wire rod in the as-rolled condition in accordance with ISO 6892-1.
9.5.3 Surface discontinuities
The method to be used for revealing and measuring surface discontinuities shall be chosen by the
supplier, as described in Annex B.
6 © ISO 2017 – All rights reserved

---------------------- Page: 10 ----------------------
ISO 16120-1:2017(E)

9.5.4 Decarburization
Testing for decarburization shall be carried out on the wire rod in the as-rolled condition, in accordance
with ISO 3887. Decarburization is inspected by microscope, preferably at a magnification of 200 ×, on a
transverse metallographic test piece that has been suitably etched.
The depth of decarburization of the sample is considered as being the average of eight measurements
at the ends of four diameters (or diagonals) located at 45° to each other, starting from the zone of
maximum decarburization and avoiding starting from a defective zone. In the calculation of the above
average value, any measuring point of the seven remaining situated in a local surface discontinuity
shall not be taken into account in the calculation. The depth of decarburization is measured normal to
the surface of the test piece.
9.5.5 Non-metallic inclusions
The tests shall be carried out on the wire rod in the as-rolled condition and in accordance with
ISO 16120-3:2011, 5.5 and ISO 16120-4:2017, 4.6.
9.5.6 Core segregation
The method for determining the core segregation shall be macrographic examination on a transverse
section of the sample, as specified in Annex A.
9.5.7 Microstructure
The tests shall be carried out on the wire rod in the as-rolled condition. The method for determining
the microstructure shall be carried out as specified in Annex D.
9.5.8 Determination of cementite network in high-carbon steel wire rod
The method for the determination of cementite network in high-carbon steel wire rod shall be carried
out as specified in Annex E.
9.6 Retest
Retests of wire rod and their criteria should be as specified in ISO 404.
10 Marking
Each coil in each consignment shall be marked with the following information:
a) dimensions of the cross-section of the wire rod;
b) steel grade;
c) heat number;
d) the name and, if applicable, the symbol of the supplying mill;
e) any subsequently agreed information (e.g. coil weight).
Unless otherwise agreed upon, the marking shall withstand pickling. The durability of the labels
utilized for marking shall be agreed upon at the time of ordering.
11 Disputes
In case of dispute, the sampling conditions and test methods used to evaluate the dispute characteristics
shall be those described in the relevant International Standard, or in ISO 404:2013, 8.3.3 and 8.3.4.
© ISO 2017 – All rights reserved 7

---------------------- Page: 11 ----------------------
ISO 16120-1:2017(E)

Annex A
(normative)

Determination of core segregation
A.1 Overview
This annex is applicable for wire rod made from continuously cast steel with a carbon content of at least
0,4 % and defined in this document. The method described in A.2 and A.3 is a macrographic method
aimed at determining and evaluating the core segregation present in continuously cast high-carbon
wire rod by revealing the carbon segregation.
A.2 Principle
Chemical heterogeneity is revealed by chemical etching of a cross-section of the wire rod using a nital
solution.
The images observed by macrographic examination are compared with the pictures shown in the
reference chart and are classified accordingly.
A.3 Preparation of samples
A.3.1 Cutting
The surface to be examined is a transverse section from each sample to be examined. This is obtained by
gradually cutting at low speed. At all times, excessive heating shall be avoided by means of appropriate
cooling.
A.3.2 Polishing
The specimen is polished stepwise by using graduated emeries and finishing with fine diamond paste
of grain size 1 µm.
After polishing to a mirror finish, the specimen is c
...