GB/T 25052-2024 (GB/T25052-2024, GBT 25052-2024, GBT25052-2024)
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Dimension,shape,weight and tolerance for continuously hot-dip coated steel sheet and strip
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GB/T 25052-2024
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| GB/T 25052-2010 | English | 190 |
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Continuously hot-dip coated steel sheet and strip -- Tolerances on dimensions, shape and weight
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GB/T 25052-2010
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| Standard ID | GB/T 25052-2024 (GB/T25052-2024) | | Description (Translated English) | Dimension, shape, weight and tolerance for continuously hot-dip coated steel sheet and strip | | Sector / Industry | National Standard (Recommended) | | Classification of Chinese Standard | H46 | | Word Count Estimation | 20,241 | | Date of Issue | 2024-08-23 | | Date of Implementation | 2024-08-23 | | Administrative Organization | National Technical Committee on Steel Standardization (SAC/TC 183) | | Proposing organization | China Light Industry Federation | | Issuing agency(ies) | State Administration for Market Regulation, National Standardization Administration |
GB/T 25052-2024
GB
NATIONAL STANDARD OF THE
PEOPLE'S REPUBLIC OF CHINA
ICS 77.140.50
CCS H 46
Replacing GB/T 25052-2010
Dimension, shape, weight and tolerance for continuously
hot-dip coated steel sheet and strip
ISSUED ON: AUGUST 23, 2024
IMPLEMENTED ON: MARCH 1, 2025
Issued by: State Administration for Market Regulation;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 6
2 Normative references ... 6
3 Terms and definitions ... 6
4 Classification and codes ... 7
5 Dimensions ... 8
5.1 Dimension range ... 8
5.2 Recommended nominal dimensions ... 8
6 Tolerances on dimensions ... 8
6.1 Tolerance on thickness ... 8
6.2 Tolerance on width ... 11
6.3 Tolerance on length ... 12
7 Appearance ... 13
7.1 Flatness tolerance ... 13
7.2 Camber ... 13
7.3 Out-of-squareness ... 14
7.4 Telescoping ... 14
8 Measurement of dimensions and shapes ... 14
8.1 Thickness ... 14
8.2 Width ... 14
8.3 Length ... 14
8.4 Flatness tolerance ... 15
8.5 Camber ... 15
8.6 Out-of-squareness ... 16
9 Weight ... 17
10 Rounding off of numerical values ... 18
References ... 19
Foreword
This document was drafted in accordance with the provisions of GB/T 1.1-2020
Directives for standardization - Part 1: Rules for the structure and drafting of
standardizing documents.
This document replaces GB/T 25052-2010 Continuously hot-dip coated steel sheet and
strip - Tolerances on dimensions, shape and weight. Compared with GB/T 25052-2010,
in addition to structural adjustments and editorial modifications, the main technical
changes are as follows:
a) The note in the Scope is deleted (see Chapter 1 of the 2010 edition);
b) Terms and definitions are added (see Chapter 3);
c) The dimensional precision classifications of wide strips, steel sheets and slit
wide strips are changed from "advanced" to "high" (see 4.2 and Tables 2~9;
see 3.1 and Tables 1~9 of the 2010 edition);
d) The dimensional and flatness precision classification corresponding to the
product form is added (see Table 1);
e) The requirements for the upper limit of the nominal width of wide strips, steel
sheets and slit wide strips are added (see 5.1.2);
f) The requirements for the upper and lower limits of the nominal length of steel
sheets are added (see 5.1.3);
g) The requirements for the recommended nominal dimensions of wide strips,
steel sheets and slit wide strips are added (see 5.2);
h) The requirements for tolerances on thicknesses of wide strips, steel sheets and
slit wide strips are modified (see Tables 2~5; see Tables 1~4 of the 2010
edition);
i) The requirements for the flatness tolerance of steel sheets with a minimum
yield strength value of less than 260 MPa and a nominal thickness of 3.0
mm~6.5 mm are modified (see Table 9; see Table 8 and Table 9 of the 2010
edition);
j) The requirements for the flatness tolerance of steel sheets with a minimum
yield strength value of not less than 360 MPa are modified (see Table 9; see
4.4.3 of the 2010 edition);
Dimension, shape, weight and tolerance for continuously
hot-dip coated steel sheet and strip
1 Scope
This document specifies the classification and designation, dimensions, dimensional
tolerances, shapes, measurement of dimensions and shapes, weights and numerical
rounding of continuously hot-dip coated steel sheets and strips.
This document is applicable to continuous hot-dip coated wide strips and their sheared
steel plates (hereinafter referred to as steel plates) and slit wide strips with a nominal
thickness not exceeding 6.5 mm.
2 Normative references
The provisions of the following documents constitute the essential clauses of this
document through normative references in this text. Among them, for referenced
documents with dates, only the versions corresponding to the dates are applicable to
this document; for referenced documents without dates, the latest versions (including
all amendments) are applicable to this document.
GB/T 8170 Rules of rounding off for numerical values & expression and judgment
of limiting values
3 Terms and definitions
The following terms and definitions apply to this document.
3.1 wide strip
Steel strip with a rolling width of not less than 600 mm and delivered in coils.
[Source: GB/T 708-2019, 3.1]
3.2 slit wide strip
Steel strip cut longitudinally from a wide strip (3.1) and delivered in coils.
[Source: GB/T 708-2019, 3.2]
3.3 nominal(specified) thickness
5 Dimensions
5.1 Dimension range
5.1.1 The nominal thickness of wide strips, steel sheets and slit wide strips shall not
exceed 6.50 mm.
5.1.2 The nominal width of wide strips, steel sheets and slit wide strips shall not exceed
2080 mm.
5.1.3 The nominal length of steel sheets is 1000 mm~8000 mm.
5.2 Recommended nominal dimensions
5.2.1 The nominal thickness of wide strips, steel sheets and slit wide strips is within the
range specified in 5.1. For steel sheets and steel strips with a nominal thickness of less
than 1.00 mm, any dimension shall be a multiple of 0.05 mm; for steel sheets and steel
strips with a nominal thickness of not less than 1.00 mm, any dimension shall be a
multiple of 0.10 mm.
5.2.2 The nominal width of wide strips, steel sheets and slit wide strips shall be any
dimension in multiples of 10 mm.
5.2.3 The nominal length of steel sheets shall be within the range specified in 5.1 and
any dimension shall be a multiple of 50 mm.
5.2.4 Based on the requirements of the buyer and after negotiation between the supply
and demand parties, wide strips, steel sheets and slit wide strips of other dimensions
can be supplied.
6 Tolerances on dimensions
6.1 Tolerance on thickness
6.1.1 The tolerances on thicknesses of wide strips, steel sheets and slit wide strips with
the specified minimum yield strength of less than 260 MPa shall comply with the
provisions of Table 2.
9 Weight
9.1 Steel sheets shall be delivered according to theoretical or actual weight, and wide
strips and slit wide strips shall be delivered according to actual weight.
9.2 When steel sheets are delivered according to theoretical weight, the theoretical
weight shall be calculated based on the nominal dimensions.
9.3 The nominal thickness of the coating is calculated according to formula (1):
where:
tz -- nominal thickness of the coating, in micrometers (μm);
mz -- double-sided coating weight, in grams per square meter (g/m2);
d -- density, in grams per cubic centimeter (g/cm3).
9.4 The density of the coating may be as follows:
a) The density of pure zinc and zinc-iron alloy coatings is 7.10 g/cm3;
b) The density of the zinc-aluminum alloy coating is 6.60 g/cm3 (the mass
fraction of aluminum in the molten zinc-aluminum alloy solution is 5%);
c) The density of the aluminum-zinc alloy coating is 3.80 g/cm3 (the mass
fraction of aluminum in the molten aluminum-zinc alloy solution is 55%, and
the mass fraction of silicon is 1.6%);
d) The density of the aluminum-silicon alloy coating is 3.03 g/cm3 (the mass
fraction of silicon in the molten aluminum-silicon alloy solution is 5%~11%);
e) The density of the zinc-aluminum-magnesium alloy coating is calculated
according to formula (2):
where:
d -- density, in grams per cubic centimeter (g/cm3);
xZn -- mole fraction of zinc in zinc-aluminum-magnesium alloy;
xAl -- mole fraction of aluminum in zinc-aluminum-magnesium alloy;
xMg -- mole fraction of magnesium in zinc-aluminum-magnesium alloy.
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