ISO 4998:2023

INTERNATIONAL ISO
STANDARD 4998
Seventh edition
2023-02
Steel sheet, zinc‐coated and zinc‐iron
alloy‐coated by the continuous hot‐dip
process, of structural quality
Tôles en acier au carbone revêtues de zinc et d'un alliage zinc-fer en
continu par immersion à chaud, de qualité destinée à la construction
Reference number
© ISO 2023
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Published in Switzerland
ii
Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Dimensions .2
5 Conditions of manufacture .3
5.1 Steelmaking . 3
5.2 Chemical composition . 3
5.3 Chemical analysis . 3
5.3.1 Heat analysis . 3
5.3.2 Product analysis . 3
5.4 Mechanical properties . 4
5.5 Coating . 4
5.5.1 Coating mass . 4
5.5.2 Coating adherence. 5
5.6 Weldability . 6
5.7 Painting . 6
5.8 Surface treatment . 6
5.8.1 Mill passivation . 6
5.8.2 Mill phosphating . 6
5.8.3 Oiling . 7
5.9 Dimensional and shape tolerances . 7
6 Sampling . 7
6.1 Chemical composition . 7
6.2 Tensile test . 7
6.3 Coating tests . 7
6.3.1 Coating mass . 7
6.3.2 Triple-spot test . 7
6.3.3 Single-spot test . 7
6.3.4 Coating adherence. 8
7 Test methods . 8
7.1 Tensile test . 8
7.2 Coating properties. 8
7.2.1 Coating mass . 8
7.2.2 Coating adherence. 8
8 Designation system . 8
8.1 General . 8
8.2 Coating type . 8
8.3 Coating mass . 8
8.4 Coating finish condition . 9
8.5 Surface treatment . 9
8.6 Example . 9
9 Retests . 9
9.1 Machining and flaws . . 9
9.2 Elongation . 10
9.3 Additional tests . 10
10 Resubmission.10
11 Workmanship .10
12 Inspection and acceptance .10
iii
13 Coil size .10
14 Marking . .11
15 Information supplied by the purchaser .11
Annex A (normative) Orders requiring base‐metal thickness .13
Bibliography .14
iv
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
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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
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www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 17, Steel, Subcommittee SC 12, Continuous
mill flat rolled products.
This seventh edition cancels and replaces the sixth edition (ISO 4998:2014), which has been technically
revised.
The main changes are as follows:
— update of terms and definitions;
— addition of coating mass designations.
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.
v
INTERNATIONAL STANDARD ISO 4998:2023(E)
Steel sheet, zinc‐coated and zinc‐iron alloy‐coated by the
continuous hot‐dip process, of structural quality
1 Scope
This document specifies the requirements for steel sheet, zinc-coated and zinc-iron alloy-coated by the
continuous hot-dip process, of structural quality.
The product is intended for applications where resistance to corrosion is of prime importance.
The steel sheet is produced in a number of grades, coating masses, ordering conditions, and surface
treatments.
This document does not cover steel sheet designated as commercial quality, or drawing quality, which
[1]
are covered in ISO 3575 .
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 1460, Metallic coatings — Hot dip galvanized coatings on ferrous materials — Gravimetric
determination of the mass per unit area
ISO 2178, Non-magnetic coatings on magnetic substrates — Measurement of coating thickness — Magnetic
method
ISO 3497, Metallic coatings — Measurement of coating thickness — X-ray spectrometric methods
ISO 6892-1, Metallic materials — Tensile testing — Part 1: Method of test at room temperature
ISO 7438, Metallic materials — Bend test
ISO 16163, Continuously hot-dipped coated steel sheet products — Dimensional and shape tolerances
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
zinc‐coated steel sheet
product obtained by hot-dip coating of cold-reduced sheet coils or hot-rolled descaled sheet coils on a
continuous zinc-coating line
3.2
zinc‐iron alloy‐coated steel sheet
product obtained by processing the zinc-coated steel sheet so that the coating formed on the base-metal
is composed of zinc-iron alloys
Note 1 to entry: This product, designated ZF, is not spangled, is normally dull in appearance, and, for some
applications, can be suitable for immediate painting without further treatment, except normal cleaning. Zinc-
iron alloy coatings can powder during severe forming.
3.3
normal coating
coating formed as a result of unrestricted growth of zinc crystals during normal solidification
Note 1 to entry: This coating has a metallic lustre and is the type normally furnished for a wide variety
of applications. It can be furnished as S (normal coating, with skin pass) or N (normal coating, no skin pass);
however, it can be variable in appearance and is not suitable for decorative painting.
3.4
minimized spangle
finish obtained by restricting normal spangle formation during the solidification of the zinc
Note 1 to entry: This product can have some lack of uniformity in surface appearance within a coil, or from coil
to coil.
3.5
differential coating
coating deliberately produced to have a different coating mass on each surface
3.6
skin pass
light cold-rolling of the product
Note 1 to entry: The purpose of the skin passing is one or more of the following: to minimize the appearance of
coil breaks, stretcher strains and fluting; to control the shape; and to obtain the required surface finish.
Note 2 to entry: Some increase in hardness and some loss in ductility will result from skin passing.
3.7
lot
up to a specified quantity of steel sheet of the same designation rolled to the same thickness and coating
condition
3.8
coating mass
total amount of coating on both sides of the sheet, expressed in grams per square metre (g/m ) of sheet
4 Dimensions
4.1 Zinc-coated and zinc-iron alloy-coated structural quality steel sheet is produced in thicknesses
from 0,25 mm to 5 mm inclusive after coating, and in widths of 600 mm and over in coils and cut
lengths. Zinc-coated and zinc-iron alloy-coated steel sheet less than 600 mm wide, slit from wide sheet,
is considered as sheet.
NOTE Thicknesses less than 0,4 mm will possibly not be available in grades 220, 250, 280, and 320.
4.2 The thickness of zinc-coated and zinc-iron alloy-coated steel sheet may be specified as a
combination of the base-metal and metallic coating, or as the base-metal alone. The purchaser shall
indicate on the order which method of specifying thickness is required. In the event that the purchaser
does not indicate any preference, the thickness as a combination of the base-metal and coating will be
provided. Annex A describes the requirements for specifying the thickness as the base-metal alone.
5 Conditions of manufacture
5.1 Steelmaking
Unless otherwise agreed by the interested parties, the processes used in making the steel and in
manufacturing zinc-coated and zinc-iron alloy-coated steel sheet of structural quality are left to the
discretion of the manufacturer. On request, the purchaser shall be informed of the steelmaking process
being used.
5.2 Chemical composition
The chemical composition (heat analysis) shall conform to the requirements given in Tables 1 and 2.
5.3 Chemical analysis
5.3.1 Heat analysis
An analysis of each heat shall be made by the manufacturer in order to determine conformity with the
requirements given in Tables 1 and 2. On request, a report of the heat analysis shall be made available
to the purchaser or the purchaser’s representative. Each of the elements listed in Tables 1 and 2
shall be included in the report of the heat analysis. When the amount of copper, nickel, chromium or
molybdenum present is less than 0,02 %, the analysis may be reported as “<0,02 %”.
5.3.2 Product analysis
A product analysis may be made by the purchaser in order to verify the specified analysis of the product
and shall take into c
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