ISO 4998:2005

INTERNATIONAL ISO
STANDARD 4998
Fourth edition
2005-11-01

Continuous hot-dip zinc-coated carbon
steel sheet of structural quality
Tôles en acier au carbone galvanisées en continu par immersion à
chaud, de qualité destinée à la construction




Reference number
ISO 4998:2005(E)
©
ISO 2005

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ISO 4998:2005(E)
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ii © ISO 2005 – All rights reserved

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ISO 4998:2005(E)
Contents Page
Foreword. iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 Requirements . 3
4.1 Chemical composition. 3
4.2 Mechanical properties. 4
4.3 Coating. 4
4.4 Weldability . 6
4.5 Painting. 6
4.6 Surface treatment . 6
4.7 Dimensional and shape tolerances. 7
5 Sampling. 7
5.1 Chemical composition. 7
5.2 Tensile test . 7
5.3 Coating tests . 7
5.4 Retest . 7
6 Test methods. 8
6.1 Tensile test . 8
6.2 Coating properties. 8
7 Designation system. 8
7.1 Coating type . 8
7.2 Coating mass . 8
7.3 Coating conditions . 8
7.4 Surface treatment . 9
7.5 Structural grades . 9
7.6 Example . 9
8 Resubmission . 9
9 Workmanship . 9
10 Inspection and acceptance. 10
11 Marking . 10
12 Information to be supplied by the purchaser . 10
Annex A (normative) Orders requiring base metal thickness . 12
Bibliography . 13

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ISO 4998:2005(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 4998 was prepared by Technical Committee ISO/TC 17, Steel, Subcommittee SC 12, Continuous mill flat
rolled products.
This fourth edition cancels and replaces the third edition (ISO 4998:1996), which has been technically revised.
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INTERNATIONAL STANDARD ISO 4998:2005(E)

Continuous hot-dip zinc-coated carbon steel sheet of structural
quality
1 Scope
This International Standard applies to continuous hot-dip zinc- and zinc-iron-alloy-coated carbon steel sheet 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 mass, ordering conditions, and surface treatments.
Zinc-coated structural quality sheet is produced in thicknesses from 0,25 mm to 5 mm after zinc coating, and
in widths of 600 mm and over in coils and cut lengths. Zinc-coated sheet less than 600 mm wide may be slit
from wide sheet and will be considered as sheet.
NOTE Thicknesses less than 0,4 mm may not be available in grades 220, 250, 280 and 320.
The thickness of zinc and zinc-iron alloy coated sheet steel may be specified as a combination of the base
metal and metallic coating, or 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 base metal alone.
This International Standard does not cover steels designated as commercial quality, or drawing quality, which
[2]
are covered in ISO 3575 .
2 Normative references
The following referenced documents are indispensable for the application 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 1460:1992, Metallic coatings — Hot dip galvanized coatings on ferrous materials — Gravimetric
determination of the mass per unit area
ISO 2178:1982, Non-magnetic coatings on magnetic substrates — Measurement of coating thickness —
Magnetic method
ISO 3497:2000, Metallic coatings — Measurement of coating thickness — X-ray spectrometric methods
ISO 6892:1998, Metallic materials — Tensile testing at ambient temperature
ISO 7438:2005, Metallic materials — Bend test
ISO 16160:2005, Continuously hot-rolled steel sheet products — Dimensional and shape tolerances
ISO 16162:2005, Continuously cold-rolled steel sheet products — Dimensional and shape tolerances
ISO 16163:2005, Continuously hot-dipped coated steel sheet products — Dimensional and shape tolerances
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ISO 4998:2005(E)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1

continuous hot-dip 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
normal coating
coating formed as a result of unrestricted growth of zinc crystals during normal solidification
NOTE This coating has a metallic lustre and is the type normally furnished for a wide variety of applications. It may
be furnished as S or N; however, it may be variable in appearance and is not suitable for decorative painting.
3.3
minimized spangle coating
coating obtained by restricting normal spangle formation during the solidification of the zinc
NOTE This product may have some lack of uniformity in surface appearance within a coil, or from coil to coil.
3.4
smooth finish
smooth coating produced by skin-passing the coated material in order to achieve an improved surface
condition as compared with the normal as-coated product.
3.5
zinc-iron alloy coating
coating produced by processing the zinc-coated steel sheet so that the coating formed on the base metal is
composed of zinc-iron alloys
NOTE This product, designated ZF, is not spangled, is normally dull in appearance, and, for some applications, may
be suitable for immediate painting without further treatment, except normal cleaning. Zinc-iron alloy coatings may powder
during severe forming.
3.6
differential coating
coating having a specified coating-mass designation on one surface, and a different coating-mass designation
on the other surface
3.7
skin pass
light cold-rolling of the zinc-coated steel sheet
NOTE The purpose of the skin pass is to produce a higher degree of surface smoothness and thereby improve the
surface appearance. The skin pass also temporarily minimizes the occurrence of a surface condition known as stretcher
strain (Luder’s Lines) or fluting during the fabrication of finished parts. The skin pass also controls and improves flatness.
Some increase in hardness and loss of ductility will result from skin passing.
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ISO 4998:2005(E)
4 Requirements
4.1 Chemical composition
The chemical composition (heat analysis) shall not exceed the values given in Tables 1 and 2. On request, a
report of the heat analysis shall be made to the purchaser.
A verification analysis (product analysis) may be made by the purchaser to verify the specified analysis of the
semi-finished or finished steel, and shall take into consideration any normal heterogeneity. Non-killed steels,
such as rimmed or capped, are not technologically suited for verification analysis.
The product analysis tolerances are shown in Table 3.
The processes used in making the steel and in manufacturing zinc-coated sheet of structural quality are left to
the discretion of the manufacturer. When requested, the purchaser shall be informed of the steel-making
process being used.
Table 1 — Chemical composition (heat analysis)
Element % max.
Carbon 0,25
Manganese 1,70

a
Phosphorus 0,05
Sulfur 0,035
a
Grades 250 and 280: phosphorus −0,10 % max.
Grade 350: phosphorus −0,20 % max.

Table 2 — Limits on additional chemical elements, %

a a a, b a, b c
Cu Ni Cr Mo Nb V Ti
Element
max. max. max. max. max. max. max.
Heat analysis 0,20 0,20 0,15 0,06 0,008 0,008 0,008
Product analysis 0,23 0,23 0,19 0,07 0,018 0,018 0,018
Each of the elements listed in this table 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 %.

a
The sum of copper, nickel, chromium and molybdenum shall not exceed 0,50 % on the heat analysis. When one or more of these
elements are specified, the sum does not apply, in which case only the individual limits on the remaining elements will apply.

b
The sum of chromium and molybdenum shall not exceed 0,16 % on heat analysis. When one or more of these elements are
specified, the sum does not apply, in which case, only the individual limits on the remaining elements will apply.

c
Heat analysis greater than 0,008 % may be supplied after agreement between the producer and purchaser.

Table 3 — Product analysis tolerances, %
Maximum of Tolerance over
Element
specified element maximum specified
Carbon 0,25 0,04
Manganese 1,70 0,14
Phosphorus 0,05 0,01
Sulfur 0,035 0,01
NOTE The above maximum tolerance is the allowable excess over the specified requirement and not the heat analysis.
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ISO 4998:2005(E)
4.2 Mechanical properties
Structural quality grades shall satisfy the mechanical properties shown in Table 4. On request, a report of the
mechanical properties shall be made to the purchaser
Table 4 — Mechanical properties

a c
R min R A min. %

eL m
Grade
2 b 2
N/mm N/mm
L = 50 mm L = 80 mm
o o
220 220 310 20 18
250 250 360 18 16
280 280 380 16 14
320 320 430 14 12
350 350 450 12 10
380 380 540 12 10
550 550 570 — —
R = lower yield stress
eL
R = tensile strength (for information only)
m
A = percentage elongation after fracture
L = gauge length on test piece
o
a
The yield stress specified in this table shall be the lower yield stress (R ) The values can also be measured by 0,5 % total
.
eL
elongation proof stress (proof stress un
...