ISO 14788:2005

Continuous hot-dip zinc-5 % aluminium alloy coated steel sheet

ISO 14788:2005 specifies the minimum requirements for steel sheet, in coils and cut lengths, metallic-coated by the continuous hot-dip process, with zinc-5% aluminium alloy coating.

Tôles en acier revêtues à chaud en continu d'alliage zinc-aluminium 5 %

General Information

• Status: Withdrawn
• Publication Date: 07-Jun-2005
• Withdrawal Date: 07-Jun-2005
• ICS: 77.140.50 - Flat steel products and semi-products
• Technical Committee: ISO/TC 17/SC 12 - Continuous mill flat rolled products
• Drafting Committee: ISO/TC 17/SC 12 - Continuous mill flat rolled products
• Current Stage: 9599 - Withdrawal of International Standard
• Completion Date: 06-Jan-2011

Relations

• Revised: ISO 14788:2011 - Continuous hot-dip zinc-5 % aluminium alloy coated steel sheet
• Effective Date: 10-Jan-2009
• Revises: ISO 14788:1998 - Continuous hot-dip zinc-5 %/aluminium alloy coated steel sheets and coils
• Effective Date: 15-Apr-2008
• Consolidated By: ISO 10439-4:2015 - Petroleum, petrochemical and natural gas industries — Axial and centrifugal compressors and expander-compressors — Part 4: Expander-compressors
• Effective Date: 06-Jun-2022

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 14788
Second edition
2005-05-15


Continuous hot-dip zinc-5 % aluminium
alloy coated steel sheet
Tôles en acier revêtues à chaud en continu d'alliage
zinc-aluminium 5 %





Reference number
ISO 14788:2005(E)
©
ISO 2005

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ISO 14788:2005(E)
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ISO 14788:2005(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 14788 was prepared by Technical Committee ISO/TC 17, Steel, Subcommittee SC 12, Continuous mill
flat rolled products.
This second edition cancels and replaces the first edition (ISO 14788:1998), which has been technically
revised.

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INTERNATIONAL STANDARD ISO 14788:2005(E)

Continuous hot-dip zinc-5 % aluminium alloy coated steel sheet
1 Scope
1.1 This International Standard specifies the minimum requirements for steel sheet, in coils and cut lengths,
metallic-coated by the continuous hot-dip process, with zinc-5 % aluminium alloy coating.
1.2 The product is intended for applications requiring corrosion resistance, formability and paintability.
1.3 The steel sheet is produced in a number of qualities and grades, coating mass, surface treatments and
coating conditions designed to be compatible with differing application requirements.
1.4 The product is produced in two types:
 T1: zinc-5 % aluminium-mischmetal alloy coating,
 T2: zinc-5 % aluminium-0,1 % magnesium alloy coating.
NOTE There may be differences in product characteristics between Type 1 and Type 2 coated steel sheet,
depending on the intended application.
1.5 Zinc-5 % aluminium alloy coated steel sheet is produced in thicknesses up to 5 mm after coating, and in
widths of 600 mm and over in coils and cut lengths. Zinc-5 % aluminium alloy coated steel sheet less than
600 mm wide may be slit from wide sheet and will be considered as sheet.
1.6 The thickness of zinc-5 % aluminium alloy coated sheet steel 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 of the base metal alone.
1.7 Zinc-5 % aluminium alloy coated steel sheet may be ordered in one of two conditions as described
in 4.2.1:
a) Condition A) Steel ordered to satisfy mechanical property requirements,
b) Condition B) Steel when ordered to make an identified part.
1.8 Zinc-5 % aluminium alloy coated steel sheet is available in several fabrication qualities.
 Commercial: intended for general fabrication purposes, where sheet is used in the flat or for bending or
moderate forming.
 Drawing: intended for fabricating parts where drawing or severe forming may be involved.
 Deep drawing-aluminium killed (non-aging): intended for fabricating parts where particularly severe
drawing or forming may be involved or essential freedom from aging is required.
 Extra deep drawing (stabilized interstitial free): intended for applications requiring interstitial-free steel (IF)
which is non-aging and has maximum formability.
 Structural: zinc-5 % aluminium alloy coated steel sheet is produced in six grades as defined by a
minimum yield stress.
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ISO 14788:2005(E)
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 16160:2000, Continuously hot-rolled steel sheet products — Dimensional and shape tolerances
ISO 16162:2000, Continuously cold-rolled steel sheet products — Dimensional and shape tolerances
ISO 16163:2000, 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.
3.1
continuous hot-dip zinc-5 % aluminium-coated steel sheet
product obtained by hot-dip coating of steel sheet coils on a continuous coating line to produce either coated
coils or cut lengths
3.2
normal spangle
coating formed as a result of the unrestricted growth of zinc-5 % aluminium alloy crystals during normal
solidification
3.3
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
3.4
skin pass
light cold rolling of the 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 fabrication of finished parts. The skin pass also controls and improves flatness.
3.5
ageing
susceptibility of zinc-5 % aluminium alloy coated steel sheet to changes in properties with the passage of time
NOTE Aging may result in a change in yield strength and corresponding decrease in ductility during storage. Aging
always has a negative effect on formability. The redevelopment of an upper yield point as a result of aging can result in
renewed susceptibility to surface imperfections, such as stretcher strain marks (Luder’s Lines) and fluting, when the steel
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ISO 14788:2005(E)
is formed. To avoid these adverse outcomes, it is essential that the period between final processing at the producing mill
and fabrication be kept to a minimum. Rotation of stock, by using the oldest material first, is important. Effective roller
leveling immediately prior to fabrication can achieve reasonable freedom from stretcher strain marks.
3.6
differential coating
coating having a coating mass on one surface significantly different from the coating mass on the other
surface
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 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 steels, 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-5 % aluminium alloy coated sheet are left
to the discretion of the manufacturer. When requested, the purchaser shall be informed of the steelmaking
process being used.
Table 1 — Chemical composition (heat analysis), %

C Mn P S Ti
Base-metal quality
max. max. max. max. max.
Commercial 0,15 0,60 0,05 0,05 —
a
Drawing 0,12 0,50 0,04 0,04 —
a
Drawing quality aluminum killed 0,08 0,45 0,03 0,03 —
a
Extra-deep drawing quality 0,02 0,25 0,02 0,02 0,15
Structural 0,40 0,20 0,04 0,05 —
a
For interstitial free steels only, the values of 0,15 % titanium, and 0,10 % maximum for niobium and vanadium, are acceptable to
ensure that the carbon and nitrogen are fully stabilized.
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ISO 14788:2005(E)
Table 2 — Limits on additional chemical elements, %

a a a, b a, b c c, d d
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
NOTE 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
For interstitial free steels only, the value of 0,15 % titanium, and 0,10 % maximum for niobium and vanadium are acceptable to
ensure that the carbon and nitrogen are fully stabilized.
d
Heat analysis greater than 0,008 % may be supplied after agreement between the producer and consumer.
Table 3 — Product analysis tolerances, %
Element Maximum of specified element Tolerance over maximum specified
C 0,25 0,04
Mn 1,70 0,14
P 0,05 0,01
S 0,035 0,01
NOTE The above maximum tolerance is the allowable excess over the specified requirement and not the heat analysis.
4.2 Mechanical properties
4.2.1 Commercial and drawing qualities
Zinc-5 % aluminium alloy coated steel sheet of designations 01, 02, 03,and 04 is supplied under the following
two ordering conditions:
a) Ordering condition A): steel when ordered to mechanical properties shall, at the time the steel is made
available for shipment, satisfy the applicable requirements of Table 4.
b) Ordering condition B): steel when ordered to make an identified part shall be supplied with a commitment
to satisfactory manufacturing performance within a properly established breakage allowance, which shall
be previously agreed upon between the interested parties. In these cases, the part name, the details of
fabrication, and special requirements (such as freedom from stretcher strain or fluting) shall be specified.
Prolonged storage of the sheet can cause a change in mechanical properties (increase in hardness and
decrease in elongation), leading to a decrease in drawability. To minimize this effect, quality 03 or 04 should
be specified.
4.2.2 Structural quality
The mechanical properties, at the time the steel is made available for shipment, shall satisfy the requirements
listed in Table 5.
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ISO 14788:2005(E)
Table 4 — Mechanical properties
a b c d
Base-metal quality R max R max A min. %
e m

b, e b, e
f
N/mm N/mm
Designation Name Lo = 50 mm Lo = 80 mm Lo = 5,65√S
o
01 Commercial — — — — —
g
02 Drawing 300 430 24 23 22
Deep drawing
03 220 410 29 28 27
aluminum killed
Extra-deep drawing
04 (stabilized interstitial 200 350 37 36 35
free)
R yield stress
e
R tensile strength
m
A percentage elongation after fracture
L gauge length of test piece
o
S original cross-sectional area of gauge length
o
e thickness of steel sheet, in millimetres
NOTE 1 Time period from date of shipment for values stated in this table to be applicable:
Designation Time period
0 —
02 8 days
03 6 months
04 6 months
NOTE 2 For products produced according to performance criteria, 4.2.1, the typical mechanical properties presented here are non-
mandatory. For products ordered according to specific mechanical properties (ordering condition A), the purchaser may negotiate with
the supplier if a specific range, or a more restrictive range, is required for the application. Therefore, by agreement, these values can be
specified.
NOTE 3 These typical mechanical properties apply to the full range of steel sheet thicknesses. The yield tends to increase and
some of the formability aspects tend to decrease as the sheet thickness decreases.
a
All qualities are available with a normal spangle or smooth finish zinc-5 % aluminium alloy coating.
b
The yield values apply to 0,2 % proof stress if the yield point is not pronounced, otherwise to the lower yield point (R ).
eL
c 2
Minimum tensile strength, for qualities 02, 03 and 04, would normally be expected to be 270 N/mm . All tensile strength values are
2
determined to the nearest 10 N/mm .
d
For material up to and including 0,6 mm in thickness, the elongation values in the table shall be reduced by 2.
e 2
1 N/mm = 1 MPa.
f
May be used for material over 3 mm in thickness.
g
This value applies to skin-passed products only.
4.3 Coating
4.3.1 Coating mass
The coating mass limits shall conform to the limits for the designations shown in Table 6. The coating mass is
the total amount of coating on both sides of the sheet, expressed in grams per square metre.
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ISO 14788:2005(E)
4.3.2 Coating adherence
The coated sheet shall be capable of being bent in any direction, in accordance with the mandrel diameter
requirements of Table 7, without flaking of the coating on the outside of the bend. Flaking of the coating within
7 mm from the edge of the test piece shall not be a cause for rejection.
Table 5 — Mechanical properties of structural-quality steels
a b
R min R min A min %
e m
Grade
N/mm2 N/mm2
Lo = 50 mm Lo = 80 mm
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
c
550 550 570 — —
NOTE In determining the base-metal mechanical properties, base-metal thickness should be measured after stripping the coating
from the end of the specimen contacting the grips of the tension-testing machine before testing.
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 under load) or by 0,2 % offset when a definite yield phenomenon is not present. When the upper
2
yield stress (R is specified, the values shall be 20 N/mm above the R values for each grade.
)
eh el
b
The elongation values in the table shall be reduced by 2 for material up to and including 0,6 mm in thickness,
c
Grade 550 is in the unannealed condition and therefore has limited ductility. If the hardness is HRB 85 or higher, no tension test is
required. Bend testing for coating adherence is not applicable to Grade 550.
Table 6 — Coating mass test limits for zinc-5 % aluminium alloy coated steel sheet
Coating designation Triple-spot test Single-spot test
total both sides total both sides
2 2
min. g/m min. g/m
ZA001 no minimum no minimum
ZA080 80 70
ZA090 90
...