ISO 20805:2005
(Main)Hot-rolled steel sheet in coils of higher yield strength with improved formability and heavy thickness for cold forming
Hot-rolled steel sheet in coils of higher yield strength with improved formability and heavy thickness for cold forming
ISO 20805:2005 applies to continuous hot-rolled steel sheet of higher yield strength with improved formability. The steel is killed, made according to a fine-grain practice and has a suitable chemical composition, which shall include microalloying elements, to provide improved formability. The steel may be treated to achieve inclusion control. The product is intended for applications where parts are to be fabricated requiring better formability than is provided by normal high-yield-strength steel sheet. It is generally used in the as-delivered condition. This product is commonly produced on a wide strip mill. This product is commonly produced in the range of thicknesses greater than 6 mm to 25 mm, and widths of 600 mm and over, in coils.
Tôles fortes en acier laminées à chaud à limite d'élasticité et aptitude au formage accues, en bobines, pour formage à froid
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 20805
First edition
2005-02-15
Hot-rolled steel sheet in coils of higher
yield strength with improved formability
and heavy thickness for cold forming
Tôles fortes en acier laminées à chaud à limite d'élasticité et aptitude au
formage accues, en bobines, pour formage à froid
Reference number
ISO 20805:2005(E)
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ISO 20805:2005(E)
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ISO 20805:2005(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 20805 was prepared by Technical Committee ISO/TC 17, Steel, Subcommittee SC 12, Continuous mill flat
rolled products.
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INTERNATIONAL STANDARD ISO 20805:2005(E)
Hot-rolled steel sheet in coils of higher yield strength with
improved formability and heavy thickness for cold forming
1Scope
1.1 This International Standard applies to continuous hot-rolled steel sheet of higher yield strength with
improved formability. The steel is killed, made according to a fine-grain practice and has a suitable chemical
composition, which shall include microalloying elements, to provide improved formability. The steel may be
treated to achieve inclusion control. The product is intended for applications where parts are to be fabricated
requiring better formability than is provided by normal high-yield-strength steel sheet. It is generally used in the
as-delivered condition. This product is commonly produced on a wide strip mill.
Because of the combination of higher strength and improved formability, it is possible to obtain savings in mass
along with better weldability (see 4.4).
1.2 This product is commonly produced in the range of thicknesses greater than 6mm to 25mm, and widths
of 600 mm and over, in coils.
1.3 This International Standard does not cover steels intended for boilers or pressure vessels, or steels
designated as commercial quality, drawing quality or structural quality, or steels rolled to cold-reduced products,
or steels designated as weathering steels, having increased atmospheric corrosion resistance, or those
products rolled on a plate mill.
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 148:1983, Steel — Charpy impact test (V-notch)
ISO 6892:1998, Metallic materials — Tensile testing at ambient temperature
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
microalloying elements
elements, such as niobium, vanadium, titanium, etc., added singly or in combination to obtain higher strength
levels combined with better formability, weldability and toughness as compared with non-alloyed steel produced
to equivalent strength levels
3.2
hot-rolled steel sheet in coils
product obtained by rolling heated steel (billet or slab) through a continuous-type mill to the required strip
thickness and tolerances
NOTE The product has a surface covered with oxide or scale resulting from the hot-rolling operation.
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ISO 20805:2005(E)
3.3
hot-rolled descaled steel sheet in coils
hot-rolled steel sheet from the surface of which oxide or scale has been removed, commonly by pickling in an
acid solution
NOTE Descaling may also be performed by mechanical means such as grit blasting. Some increase in hardness and some
loss of ductility may result from descaling.
3.4
mill edge
a normal edge produced without any definite contour produced in hot-rolling.
NOTE Mill edges may contain some irregularities such as cracked or torn edges or thin (feathered) edges.
3.5
sheared edge
a normal edge obtained by shearing, slitting or trimming a mill edge product
NOTE Normal processing does not necessarily provide a definite positioning of the slitting burr.
4 Conditions of manufacture
4.1 Steelmaking
Unless otherwise agreed upon by the interested parties, the processes used in making the steel and in
manufacturing hot-rolled sheet are left to the discretion of the manufacturer. On request, the purchaser shall be
informed of the steelmaking process being used.
4.2 Chemical composition
4.2.1 The chemical composition (heat analysis) shall conform to the requirements in Tables 1 and 2.
4.2.2 The steel covered by this International Standard shall contain microalloying elements. The chemical
composition may be agreed between the interested parties at the time of enquiry and ordering.
Table 1 — Chemical analysis (heat analysis)
Carbon Manganese Phosphorus Sulfur
All grades
0,15 max., % 1,65 max., % 0,025 max., % 0,030 max., %
NOTE 1 As the form of sulfide inclusions may have a certain influence on the cold forming properties of the products, the manufacturers
may, at their discretion, influence the form of inclusions by adding certain elements, such as Ce or Ca, or may choose a very low sulfur
content for these steels.
NOTE 2 These steels shall also contain one or more of the following elements: vanadium, titanium or niobium. Other alloying elements
may be present, but are not required.
Table 2 — Limits on additional chemical elements
Copper, max. % Heat analysis 0,20
Product analysis 0,23
Nickel, max. % Heat analysis 0,20
Product analysis 0,23
Chromium, max. % Heat analysis 0,15
Product analysis 0,19
Molybdenum, max. % Heat analysis 0,06
Product analysis 0,07
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ISO 20805:2005(E)
4.3 Chemical analysis
4.3.1 Heat analysis
A heat analysis of each heat of steel shall be made by the manufacturer to determine the percentage of carbon,
manganese, phosphorus and sulphur, and the contents of other elements giving the specified mechanical
strength and formability. On request, this analysis shall be reported to the purchaser or his representative.
4.3.2 Product analysis
A product analysis may be made by the purchaser to verify the specified analysis of the product and shall take
into consideration any normal heterogeneity. Non-killed steels (such as rimmed or capped) are not
technologically suited to product analysis. For killed steels, the sampling method shall be agreed upon between
the interested parties at the time of ordering. The product analysis tolerances shall be in accordance with
Table 3.
Table 3 — Product analysis tolerances
Element Maximum of specified element, Tolerance over maximum specified,
%%
Carbon � 0,15 0,03
Manganese > 1,15 to � 1,65 0,05
Phosphorus � 0,04 0,010
Sulfur 0� 0,06 ,010
NOTE The above maximum tolerance is the allowable excess over the specified requirement and not the heat analysis. For example: for
all grades in this standard the following product analysis values are within these tolerances: C 0,18 %, Mn 1,70 %, P 0,035 %, S 0,040 %.
4.4 Weldability
This product is normally suitable for welding if appropriate welding conditions are selected. For undescaled
steel, it may be necessary to remove the scale or oxide depending upon the welding method. As the carbon
content increases above 0,15 %, spot welding becomes increasingly difficult.
4.5 Application
It is desirable that hot-rolled steel sheet be identified for fabrication by the name of the part or by the intended
application. Proper identification of the part may include visual examination, prints or description, or a
combination of these.
4.6 Mechanical properties
At the time that the steel is made available for shipment, the mechanical properties shall be as stated in Table 4,
when they are determined on test pieces in accordance with the
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