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GB/T 25052-2024 English PDF (GBT25052-2024)
GB/T 25052-2024 English PDF (GBT25052-2024)
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GB/T 25052-2024: Dimension,shape,weight and tolerance for continuously hot-dip coated steel sheet and strip
GB/T 25052-2024.Continuously hot-dip coated steel sheets and strips - Dimensions, shapes, weights and tolerances
National Standard of the People's Republic of China
Replace GB/T 25052-2010
Released on 2024-08-23
2025-03-01 Implementation
State Administration for Market Regulation
The National Standardization Administration issued
1 Scope
This document specifies the classification and code, dimensions, dimensional tolerances, shape, dimensions and shape of continuously hot-dip coated steel sheets and strips.
Measurements, weights and values are rounded off.
This document applies to continuous hot-dip coated wide steel strip and its sheared steel plate (hereinafter referred to as steel plate), longitudinally cut steel strip with a nominal thickness not exceeding 6.5 mm
Steel belt.
2 Normative references
The contents of the following documents constitute the essential clauses of this document through normative references in this document.
For referenced documents without a date, only the version corresponding to that date applies to this document; for referenced documents without a date, the latest version (including all amendments) applies.
in this document.
GB/T 8170 Rules for rounding off values and expression and determination of limit values
3 Terms and definitions
The following terms and definitions apply to this document.
4 Classification and code
4.1 The classification and codes according to edge status are as follows.
a) Cut edge, EC;
b) No cutting edge, EM.
4.2 The classification and codes according to dimensional accuracy are as follows.
a) General thickness accuracy, PT.A;
b) High thickness accuracy, PT.B;
c) Normal width accuracy, PW.A;
d) Higher width accuracy, PW.B;
e) General length accuracy, PL.A;
f) Higher length accuracy, PL.B.
4.3 The classification and codes according to roughness accuracy are as follows.
a) General roughness accuracy, PF.A;
b) Higher roughness accuracy, PF.B.
4.4 The classification of dimensional accuracy and roughness accuracy corresponding to product forms is shown in Table 1.
5.Dimensions
5.1 Size range
5.1.1 The nominal thickness of wide steel strip, steel plate and longitudinally cut steel strip shall not exceed 6.50 mm.
5.1.2 The nominal width of wide steel strips, steel plates and longitudinally cut steel strips shall not exceed 2 080 mm.
5.1.3 The nominal length of the steel plate is 1 000 mm to 8 000 mm.
5.2 Recommended nominal dimensions
5.2.1 The nominal thickness of wide steel strips, steel plates and longitudinally cut steel strips is within the range specified in 5.1.The nominal thickness of steel plates and steel strips is less than 1.00 mm.
Any dimension in multiples of 0.05 mm; any dimension in multiples of 0.10 mm for steel plates and steel strips with a nominal thickness of not less than 1.00 mm.
5.2.2 The nominal width of wide steel strip, steel plate and longitudinally cut steel strip shall be any dimension in multiples of 10 mm.
5.2.3 The nominal length of the steel plate shall be within the range specified in 5.1 and any dimension in multiples of 50 mm.
5.2.4 Based on the requirements of the purchaser and after negotiation between the supply and demand parties, wide steel strips, steel plates and longitudinally cut steel strips of other sizes can be supplied.
6.Dimensional tolerances
6.1 Thickness tolerance
6.1.1 The allowable thickness deviation of wide steel strips, steel plates and longitudinally cut steel strips with a specified minimum yield strength less than 260 MPa shall comply with the provisions of Table 2.
6.1.2 The thickness tolerance of wide steel strip, steel plate and longitudinally cut steel strip with a minimum yield strength of not less than 260 MPa and less than 360 MPa shall comply with
The provisions of Table 3 shall apply.
6.1.4 The allowable thickness deviation of wide steel strips, steel plates and longitudinally cut steel strips with a specified minimum yield strength greater than 420 MPa shall comply with the provisions of Table 5.
6.1.5 When the yield strength and thickness tolerances are not specified in the document specifying the product requirements, the thickness of wide strip, plate and longitudinally cut strip shall be
The allowable thickness deviation shall be negotiated by the supplier and the buyer and shall be specified in the contract.
6.1.6 If the purchaser requires a higher thickness accuracy (PT.B), this should be indicated in the contract. If not indicated, the normal thickness accuracy (PT.A) shall be used.
Availability.
6.1.7 Unless otherwise specified, the allowable thickness deviation within 10 m from the weld of wide steel strip and longitudinally cut steel strip may be increased by 100% compared with the values specified in Tables 2 to 5.
50%.
6.1.8 For wide steel strips, steel plates and longitudinally cut steel strips with the sum of the weight of the double-sided coating not less than 450 g/m2, the thickness tolerance shall be greater than that in Table 2~
The values specified in Table 5 shall be increased by ±0.01 mm.
6.2 Width tolerance
6.2.1 The width tolerance of trimmed wide steel strips and steel plates shall comply with the provisions of Table 6.The width tolerance of untrimmed steel plates and wide steel strips shall be determined by the supplier.
It needs to be determined through negotiation between both parties.
6.2.2 The allowable deviation of the width of longitudinally cut steel strips with a width less than 600 mm shall comply with the provisions of Table 7.The width of longitudinally cut steel strips with a width not less than 600 mm shall comply with the provisions of Table 7.
The allowable deviation of the degree shall comply with the provisions of Table 7.
6.2.3 If the purchaser requires a higher width accuracy (P WB), it should be specified in the contract. If not specified, the normal width accuracy shall be used.
(PW.A) supplies.
6.3 Length tolerance
The allowable deviation of the length of the steel plate shall comply with the provisions of Table 8.
7 Appearance
7.1 Roughness
7.1.1 The unevenness of the steel plate shall comply with the requirements of Table 9.If the purchaser requires a higher unevenness accuracy (PF.B), this should be noted in the contract.
If not specified, the product shall be supplied according to the normal unevenness accuracy (PF.A).
After the wide steel strip and the longitudinally cut steel strip are fully flattened and straightened, the values specified in Table 9 are also applicable to the steel plates cut from the wide steel strip and the longitudinally cut steel strip.
7.1.2 When the yield strength and unevenness are not specified in the document specifying the product requirements, the unevenness of the steel plate shall be determined by negotiation between the supplier and the buyer.
and specified in the contract.
7.2 Sickle
The camber of wide steel strips and steel plates should not be greater than 5 mm over any 2 000 mm length; when the length of the steel plate is less than 2 000 mm, the camber of the steel plate should not be greater than 5 mm over any 2 000 mm length.
The blade camber should not exceed 0.25% of the actual length of the steel plate. The sickle camber of the longitudinally cut steel strip should not exceed 2 mm over any 2 000 mm length.
7.3 Desquareness
The steel plate should be cut into right angles. When the projection method is used to measure the squareness, it should not be greater than 1% of the actual width of the steel plate. When the diagonal method is used to measure the squareness, it should not be greater than 1% of the actual width of the steel plate.
Half of the difference in angle line length (absolute value) should not be greater than 0.7% of the actual width of the steel plate (｜X1-X2｜/2≤0.7%×actual width).
The projection method shall be followed during arbitration.
7.4 Tower
Wide steel strips and longitudinally cut steel strips should be firmly rolled, and the tower height on one side of the wide steel strip and longitudinally cut steel strip rolls should comply with the requirements of Table 10.
8 Measurement of dimensions and shape
8.1 Thickness
The uncut width of steel strips and steel plates is measured at a distance of not less than 40 mm from the rolled edge; the cut width of steel strips and steel plates is measured at a distance of not less than
When the width of the longitudinally cut steel strip is less than 50 mm, measure along the center of the width.
8.2 Width
Measured in a direction perpendicular to the center line of the steel plate, wide steel strip or longitudinally cut steel strip.
8.3 Length
The length of the largest rectangle in the steel plate.
8.4 Roughness
8.4.1 Place the steel plate freely on the platform and do not apply any pressure except the weight of the steel plate itself. Measure the distance between the lower surface of the steel plate and the platform.
The maximum distance is shown in Figure 1.
Description of index number.
1─Unevenness.
Figure 1.Measurement of roughness
8.4.2 If the length of the testing platform is limited, for steel plates longer than 2 000 mm, any section of 2 000 mm may be cut for unevenness testing.
Measurement is used instead of full length unevenness measurement.
8.5 Sickle
The camber of wide steel strip, steel plate and longitudinally cut steel strip refers to the maximum distance between the side and the straight line connecting the two end points of the measuring part.
The concave side is measured as shown in Figure 2.
8.6 De-squareness
The out-of-squareness of the steel plate is measured by one of the following two methods.
Projection method. The vertical projection length of the horizontal side of the steel plate on the vertical side, as shown in Figure 3.a)
9 Weight
9.1 Steel plates shall be delivered according to theoretical or actual weight, and wide steel strips and longitudinally cut steel strips shall be delivered according to actual weight.
9.2 Theoretical weight of steel plates When delivered, the theoretical weight shall be calculated based on the nominal size.
9.3 The nominal thickness of the coating is calculated according to formula (1).
9.4 The density of the coating may be as follows.
a) The density of pure zinc and zinc-iron alloy coating 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 aluminum-zinc alloy coating is 3.80 g/cm3 (the mass fraction of aluminum in the molten aluminum-zinc alloy solution is 55%, the mass fraction of silicon is
1.6%));
d) The aluminum-silicon alloy coating is 3.03 g/cm3 (the mass fraction of silicon in the molten aluminum-silicon alloy solution is 5% to 11%);
e) Zinc-aluminum-magnesium alloy coating according to the formula
9.5 The calculation method for the theoretical weight of steel plates shall be in accordance with the provisions of Table 11.
10 Rounding off
The measurement results are rounded off according to the rounding value comparison method, and the rounding rules are in accordance with the provisions of GB/T 8170.
Get Quotation: Click GB/T 25052-2024 (Self-service in 1-minute)
Historical versions (Master-website): GB/T 25052-2024
Preview True-PDF (Reload/Scroll-down if blank)
GB/T 25052-2024: Dimension,shape,weight and tolerance for continuously hot-dip coated steel sheet and strip
GB/T 25052-2024.Continuously hot-dip coated steel sheets and strips - Dimensions, shapes, weights and tolerances
National Standard of the People's Republic of China
Replace GB/T 25052-2010
Released on 2024-08-23
2025-03-01 Implementation
State Administration for Market Regulation
The National Standardization Administration issued
1 Scope
This document specifies the classification and code, dimensions, dimensional tolerances, shape, dimensions and shape of continuously hot-dip coated steel sheets and strips.
Measurements, weights and values are rounded off.
This document applies to continuous hot-dip coated wide steel strip and its sheared steel plate (hereinafter referred to as steel plate), longitudinally cut steel strip with a nominal thickness not exceeding 6.5 mm
Steel belt.
2 Normative references
The contents of the following documents constitute the essential clauses of this document through normative references in this document.
For referenced documents without a date, only the version corresponding to that date applies to this document; for referenced documents without a date, the latest version (including all amendments) applies.
in this document.
GB/T 8170 Rules for rounding off values and expression and determination of limit values
3 Terms and definitions
The following terms and definitions apply to this document.
4 Classification and code
4.1 The classification and codes according to edge status are as follows.
a) Cut edge, EC;
b) No cutting edge, EM.
4.2 The classification and codes according to dimensional accuracy are as follows.
a) General thickness accuracy, PT.A;
b) High thickness accuracy, PT.B;
c) Normal width accuracy, PW.A;
d) Higher width accuracy, PW.B;
e) General length accuracy, PL.A;
f) Higher length accuracy, PL.B.
4.3 The classification and codes according to roughness accuracy are as follows.
a) General roughness accuracy, PF.A;
b) Higher roughness accuracy, PF.B.
4.4 The classification of dimensional accuracy and roughness accuracy corresponding to product forms is shown in Table 1.
5.Dimensions
5.1 Size range
5.1.1 The nominal thickness of wide steel strip, steel plate and longitudinally cut steel strip shall not exceed 6.50 mm.
5.1.2 The nominal width of wide steel strips, steel plates and longitudinally cut steel strips shall not exceed 2 080 mm.
5.1.3 The nominal length of the steel plate is 1 000 mm to 8 000 mm.
5.2 Recommended nominal dimensions
5.2.1 The nominal thickness of wide steel strips, steel plates and longitudinally cut steel strips is within the range specified in 5.1.The nominal thickness of steel plates and steel strips is less than 1.00 mm.
Any dimension in multiples of 0.05 mm; any dimension in multiples of 0.10 mm for steel plates and steel strips with a nominal thickness of not less than 1.00 mm.
5.2.2 The nominal width of wide steel strip, steel plate and longitudinally cut steel strip shall be any dimension in multiples of 10 mm.
5.2.3 The nominal length of the steel plate shall be within the range specified in 5.1 and any dimension in multiples of 50 mm.
5.2.4 Based on the requirements of the purchaser and after negotiation between the supply and demand parties, wide steel strips, steel plates and longitudinally cut steel strips of other sizes can be supplied.
6.Dimensional tolerances
6.1 Thickness tolerance
6.1.1 The allowable thickness deviation of wide steel strips, steel plates and longitudinally cut steel strips with a specified minimum yield strength less than 260 MPa shall comply with the provisions of Table 2.
6.1.2 The thickness tolerance of wide steel strip, steel plate and longitudinally cut steel strip with a minimum yield strength of not less than 260 MPa and less than 360 MPa shall comply with
The provisions of Table 3 shall apply.
6.1.4 The allowable thickness deviation of wide steel strips, steel plates and longitudinally cut steel strips with a specified minimum yield strength greater than 420 MPa shall comply with the provisions of Table 5.
6.1.5 When the yield strength and thickness tolerances are not specified in the document specifying the product requirements, the thickness of wide strip, plate and longitudinally cut strip shall be
The allowable thickness deviation shall be negotiated by the supplier and the buyer and shall be specified in the contract.
6.1.6 If the purchaser requires a higher thickness accuracy (PT.B), this should be indicated in the contract. If not indicated, the normal thickness accuracy (PT.A) shall be used.
Availability.
6.1.7 Unless otherwise specified, the allowable thickness deviation within 10 m from the weld of wide steel strip and longitudinally cut steel strip may be increased by 100% compared with the values specified in Tables 2 to 5.
50%.
6.1.8 For wide steel strips, steel plates and longitudinally cut steel strips with the sum of the weight of the double-sided coating not less than 450 g/m2, the thickness tolerance shall be greater than that in Table 2~
The values specified in Table 5 shall be increased by ±0.01 mm.
6.2 Width tolerance
6.2.1 The width tolerance of trimmed wide steel strips and steel plates shall comply with the provisions of Table 6.The width tolerance of untrimmed steel plates and wide steel strips shall be determined by the supplier.
It needs to be determined through negotiation between both parties.
6.2.2 The allowable deviation of the width of longitudinally cut steel strips with a width less than 600 mm shall comply with the provisions of Table 7.The width of longitudinally cut steel strips with a width not less than 600 mm shall comply with the provisions of Table 7.
The allowable deviation of the degree shall comply with the provisions of Table 7.
6.2.3 If the purchaser requires a higher width accuracy (P WB), it should be specified in the contract. If not specified, the normal width accuracy shall be used.
(PW.A) supplies.
6.3 Length tolerance
The allowable deviation of the length of the steel plate shall comply with the provisions of Table 8.
7 Appearance
7.1 Roughness
7.1.1 The unevenness of the steel plate shall comply with the requirements of Table 9.If the purchaser requires a higher unevenness accuracy (PF.B), this should be noted in the contract.
If not specified, the product shall be supplied according to the normal unevenness accuracy (PF.A).
After the wide steel strip and the longitudinally cut steel strip are fully flattened and straightened, the values specified in Table 9 are also applicable to the steel plates cut from the wide steel strip and the longitudinally cut steel strip.
7.1.2 When the yield strength and unevenness are not specified in the document specifying the product requirements, the unevenness of the steel plate shall be determined by negotiation between the supplier and the buyer.
and specified in the contract.
7.2 Sickle
The camber of wide steel strips and steel plates should not be greater than 5 mm over any 2 000 mm length; when the length of the steel plate is less than 2 000 mm, the camber of the steel plate should not be greater than 5 mm over any 2 000 mm length.
The blade camber should not exceed 0.25% of the actual length of the steel plate. The sickle camber of the longitudinally cut steel strip should not exceed 2 mm over any 2 000 mm length.
7.3 Desquareness
The steel plate should be cut into right angles. When the projection method is used to measure the squareness, it should not be greater than 1% of the actual width of the steel plate. When the diagonal method is used to measure the squareness, it should not be greater than 1% of the actual width of the steel plate.
Half of the difference in angle line length (absolute value) should not be greater than 0.7% of the actual width of the steel plate (｜X1-X2｜/2≤0.7%×actual width).
The projection method shall be followed during arbitration.
7.4 Tower
Wide steel strips and longitudinally cut steel strips should be firmly rolled, and the tower height on one side of the wide steel strip and longitudinally cut steel strip rolls should comply with the requirements of Table 10.
8 Measurement of dimensions and shape
8.1 Thickness
The uncut width of steel strips and steel plates is measured at a distance of not less than 40 mm from the rolled edge; the cut width of steel strips and steel plates is measured at a distance of not less than
When the width of the longitudinally cut steel strip is less than 50 mm, measure along the center of the width.
8.2 Width
Measured in a direction perpendicular to the center line of the steel plate, wide steel strip or longitudinally cut steel strip.
8.3 Length
The length of the largest rectangle in the steel plate.
8.4 Roughness
8.4.1 Place the steel plate freely on the platform and do not apply any pressure except the weight of the steel plate itself. Measure the distance between the lower surface of the steel plate and the platform.
The maximum distance is shown in Figure 1.
Description of index number.
1─Unevenness.
Figure 1.Measurement of roughness
8.4.2 If the length of the testing platform is limited, for steel plates longer than 2 000 mm, any section of 2 000 mm may be cut for unevenness testing.
Measurement is used instead of full length unevenness measurement.
8.5 Sickle
The camber of wide steel strip, steel plate and longitudinally cut steel strip refers to the maximum distance between the side and the straight line connecting the two end points of the measuring part.
The concave side is measured as shown in Figure 2.
8.6 De-squareness
The out-of-squareness of the steel plate is measured by one of the following two methods.
Projection method. The vertical projection length of the horizontal side of the steel plate on the vertical side, as shown in Figure 3.a)
9 Weight
9.1 Steel plates shall be delivered according to theoretical or actual weight, and wide steel strips and longitudinally cut steel strips shall be delivered according to actual weight.
9.2 Theoretical weight of steel plates When delivered, the theoretical weight shall be calculated based on the nominal size.
9.3 The nominal thickness of the coating is calculated according to formula (1).
9.4 The density of the coating may be as follows.
a) The density of pure zinc and zinc-iron alloy coating 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 aluminum-zinc alloy coating is 3.80 g/cm3 (the mass fraction of aluminum in the molten aluminum-zinc alloy solution is 55%, the mass fraction of silicon is
1.6%));
d) The aluminum-silicon alloy coating is 3.03 g/cm3 (the mass fraction of silicon in the molten aluminum-silicon alloy solution is 5% to 11%);
e) Zinc-aluminum-magnesium alloy coating according to the formula
9.5 The calculation method for the theoretical weight of steel plates shall be in accordance with the provisions of Table 11.
10 Rounding off
The measurement results are rounded off according to the rounding value comparison method, and the rounding rules are in accordance with the provisions of GB/T 8170.
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