GB/T 2518-2004 Continuously hot-dip galvanized steel sheets and strips
Some standard content:
ICS77.140.50
National Standard of the People's Republic of China
GB/T2518—2004
Replaces GB/T2518—1988
Continuous hot-dip zinc-coated steel sheets and strips
Continuous hot-dip zinc-coated steel sheets and strips2004-05-09 Issued
Digital two injuries
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China Standardization Administration of China
2004-10-01 Implementation
National Standard of the People's Republic of China
Continuous hot-dip zinc-coated steel sheets and strips
GB/T2518--2004
Chinese Standard Published by China Standard Press
No.16, Sanlihebei Street, Fuxingmenwai, Beijing
Postal code: 100045
Website: bzcbs.com
Tel: 6852394668517548
Printed by Zahuangdao Printing Factory of China Standard Press Distributed by Xinhua Bookstores in various regions
Format: 880×1230
Printing sheet: 1
Word count: 26,000
First edition September 2004
First printing September 2004
If there is any printing error, the distribution center of our company will replace it. Copyright infringement will be investigated
Report phone: (010) 68533533
GB/T2518—2004
This standard refers to ISO3575:1996 "Commodity grade, fixed forming grade and stamping grade continuous hot-dip galvanized carbon This standard replaces GB/T2518-1988 "Continuously Hot-dip Galvanized Steel Sheets and Strips". Compared with GB/T2518-1988, this standard has revised the following major technical contents: - Added normative reference documents, technical requirements, information provided by the purchaser, inspection, re-inspection, examination and acceptance, etc.; - Added hot-rolled pickled strip steel as the base material of galvanized steel sheet, expanding the thickness range of the product; - Added the content of chemical composition of galvanized steel sheet; - Added structural grade galvanized steel sheet series: - Added the type of zinc-free galvanized layer;
- Added the coating classification of coating weight;
Changed the surface quality level classification method,
Added three surface treatment items of paint sealing, phosphating and no treatment: Canceled the provisions on the cupping value of galvanized steel sheet, and added the provisions of n and wide values. Appendix A of this standard is the appendix of the standard.
This standard is proposed by China Iron and Steel Association. This standard is under the jurisdiction of the National Steel Standardization Technical Committee. Drafting units of this standard: Wuhan Iron and Steel (Group) Corporation, Metallurgical Industry Information Standards Research Institute, Huangshi Shanli Coating Engineering Technology Co., Ltd.
The main drafters of this standard are: Yang Dake, Liu Youren, Huang E, Zheng Hongdao, He Mingwen, Yang Chunfu, Zhang Caifu, Su Weijia. The previous versions of the standards replaced by this standard are: GB2518-1981. GB2518-1988.
1 Scope
Continuous hot-dip galvanized steel sheets and strips
GB/T2518-2004
This standard specifies the definition, classification and code, size, shape, weight and allowable deviation, technical requirements, test methods, inspection rules, packaging, marking and quality certificate of continuous hot-dip galvanized steel sheets and strips (hereinafter referred to as steel sheets and strips). This standard is applicable to continuous hot-dip galvanized ordinary grade, mechanical bite grade, stamping grade (03, 04, 05, 06 grade), and structural grade steel sheets and strips with a width of not less than 600mm and a nominal thickness of 0.20mm~5.0mm. 2 Normative references
The clauses in the following documents become clauses of this standard through reference in this standard. For any dated referenced document, all subsequent amendments (excluding errata) or revisions are not applicable to this standard. However, parties to an agreement based on this standard are encouraged to study whether the latest versions of these documents can be used. For any undated referenced document, the latest version shall apply to this standard. GB/T222--1984 Sampling method for chemical analysis specimens and allowable deviation of chemical composition of finished products GB/T228 Room temperature tensile test method for metallic materials (GB/T228-2002.eqvISO6892:1998) GB/T232 Bend test method for metallic materials (GB/T232-1999, eqvISO7438:1985) General provisions for acceptance, packaging, marking and quality certification of steel plates and strips GB/T247|| tt||GB/T708
Dimensions, shapes, weights and allowable deviations of cold-rolled steel sheets and strips GB/T709
Dimensions, shapes, weights and allowable deviations of hot-rolled steel sheets and strips GB/T1839
GB/T2975
GB/T4336
GB/T5027
GB/T5028
10275:1993)
Steel products Hot dip galvanizing layer quality wind test method (GB/T1839-1993, neqISO1460:1973) Sampling location and sample preparation for mechanical properties test of steel and steel products (GB/T2975-1998, eqvISO377: Spark source atomic emission spectrometry analysis method for carbon steel and medium and low alloy steel (conventional method) Test method for plastic strain ratio (r value) of metal sheet and thin strip (GB/T5027-1999, eqvISO10113: Metal thin Test method for tensile strain hardening index (n value) of plate and thin strip (GB/T5028--1999, eqvISO GB/T8170 Numerical rounding rules
GB/T17505 Steel and steel products delivery - general technical requirements (GB/T17505-1998, eqvISO404:1992) 3 Terms and definitions
Continuously hot-dip galvanized steel plate and strip continuoushot-dipzinc-coated Steel sheets and strips Continuously hot-dip galvanized steel sheets and strips are galvanized steel sheets and strips obtained by immersing cold-rolled steel strips or hot-rolled pickled steel strips in a plating solution with a zinc content (mass fraction) of not less than 98% on a continuous production line. 3.2
Normal spangle coating
During the normal solidification process of the zinc layer, the zinc grains grow and form a coating with obvious spangle morphology. 3.3
minimized spangle coating
Small zinc spangle coating
During the solidification process of the zinc layer, the zinc grains are artificially restricted to form a zinc spangle coating that is as small as possible. GB/T2518—2004
Spangle-free coating
A coating obtained by adjusting the chemical composition of the plating solution, which has no visually visible zinc spangle morphology and a uniform surface. 3.5
Zinc-iron alloy coating zinc-iron alloy coating The steel strip after passing through the galvanizing tank is heat-treated to form an alloy layer of zinc and iron on the entire coating. This coating has a dark gray appearance and no metallic luster. It is easy to powderize during the intense forming process. It is suitable for coatings that can be directly painted without further treatment except for general cleaning.
Differential coating
Differential coating
For the two sides of the galvanized steel sheet, a coating with different zinc layer weight is required. 3.7
Skinpass
Skinpass is a cold rolling process with a small amount of deformation on galvanized steel sheets for one or more of the following purposes. a) To improve the surface appearance of galvanized steel sheets or to make them suitable for decorative coatings; to temporarily minimize the slip lines (Lüders lines) or wrinkles produced during the processing of finished parts, etc. b)
4 Classification and code
The classification and code of performance levels shall be in accordance with the provisions of Table 1. 4.1
Table 1 Classification and code of performance
General purpose
Mechanical bite
Special killed steel deep drawing
Non-aging ultra-deep drawing
Performance level code
220, 250, 280.320.350.400, 450.550 The types and codes of the substrate shall be in accordance with the provisions of Table 2. Types and codes of substrates
Types of substrates
Cold rolled coil
Hot rolled pickled coil
Scope of application
Code for zinc layer weight shall not exceed Z350
Thickness range is ≥0.4mm
Zinc layer weight shall not exceed Z275
Steel plates with thickness <0.4mm
Not applicable to 220, 250, 280 and 320 grades
4.3 Classification and codes of coating types and coating weight Galvanized steel sheets and steel strips are suitable for anti-magic purposes. The protective effect of the zinc coating in the atmosphere is proportional to the weight of the zinc layer per unit area. The weight of the zinc layer should be consistent with the required service life, plate thickness, and forming requirements and adaptation. 4.3.1 The classification and codes of the types and coating weight of double-sided equal thickness coatings shall be in accordance with the provisions of Table 3. With the agreement between the supplier and the buyer, the steel sheets and strips with coating weights not listed in Table 3 can also be provided.
Coating weight/
(g/m2)(double-sided)
Classification and code of coating type and coating weightZinc coating
Note: The zinc coating weight in brackets needs to be negotiated by the supplier and the buyer. Coating weight/
(g/m2)(double-sided)
Zinc-iron alloy coating
GB/T2518—2004
(ZF40)
(ZF180)
4.3.2 Differential thickness coating can be expressed as half of the coating weight listed in Table 3, respectively, with different coating weights on the upper and lower surfaces, such as: Z40/90 or ZF30/50. The surface appearance of a low zinc coating weight may be different from the surface appearance of a high zinc coating weight. 4.4 The classification and code of the zinc layer surface structure shall be in accordance with the provisions of Table 4. Due to the strain aging, the 01-04 grade steel plates and strips that have been smoothed can be properly leveled by the user before processing by an effective straightening machine to avoid the generation of slip lines. The 05 or 06 grade steel plates and strips that have been smoothed are non-aging smoothed steel plates and strips, which can avoid the generation of slip lines within 6 months.
Table 4 Classification and code of zinc layer surface structure and smooth surface Surface structure
Normal zinc flower
Small zinc flower
No zinc flower
Zinc-iron alloy
The classification and code of surface quality shall be in accordance with the provisions of Table 5. Unfinished
Table 5 Classification and code of surface quality
Surface quality
Ordinary surface
Higher-grade surface
High-grade surface
GB/T2518--2004
4.6 Classification and code of surface treatment shall be in accordance with the provisions of Table 6. Table 6 Classification and code of surface treatment
Surface treatment
No treatment
4.6.1 Passivation
Galvanized coating can reduce rust (white rust) produced under humid storage and transportation conditions through passivation treatment. However, the anti-corrosion performance of this chemical treatment is limited, and it hinders the adhesion of most coatings. This treatment is generally not used for zinc-iron alloy coatings. Except for the smooth surface, as a routine, the manufacturer performs passivation treatment on other types of galvanized coatings. 4.6.2 Oiling
Oiling can reduce the rust of steel sheets under humid storage and transportation conditions. Re-oiling of steel sheets and steel strips after passivation treatment will further reduce rust under humid storage conditions.
The oil layer should be removable with a degreaser that does not damage the zinc layer. 4.6.3 Paint sealing
By applying a very thin layer of transparent organic coating film, it can provide an additional corrosion protection effect, especially anti-fingerprint properties. It can improve lubricity during molding and serve as an adhesion base for subsequent coatings. 4.6.4 Phosphating
Through phosphating treatment, galvanized steel sheets of various coating types can be coated without further treatment except normal cleaning. This treatment can improve the adhesion and corrosion resistance of the coating and reduce the risk of corrosion during storage and transportation. After phosphating, it can be used with a suitable lubricant to improve molding properties.
4.6.5 No treatment
Only when the orderer makes a request for no treatment and is responsible for it, the steel plates and strips supplied in accordance with this standard may not be subjected to surface treatment such as passivation, oiling, lacquering or phosphating. 5 Dimensions, shape, weight and allowable deviations
5.1 Dimensions and allowable deviations
5.1.1 The size range of steel plates and strips with hot-rolled pickled coils as the base material shall comply with the provisions of GB/T709, and the size range of steel plates and strips with cold-rolled coils as the base material shall comply with the provisions of GB/T708.
5.1.2 Thickness allowable deviation
5.1.2.1 The thickness allowable deviation of steel plates and strips with hot-rolled pickled coils as the base material shall comply with the provisions of GB/T709. 5.1.2.2 The thickness allowable deviation of steel plates and strips with cold-rolled coils as the base material shall comply with the provisions of Table 7. 5.1.2.3 When measuring the thickness of steel plates and strips, the thickness of the coating shall be included. 5.1.2.4 The thickness measurement position is any point not less than 25mm from the edge. 4
Nominal width
≤1500
Table 7 Thickness Permissible Deviation
Nominal thickness
GB/T2518-2004
Unit is millimeter
5.1.2.5 The thickness deviation within the total length of 30m of the head and tail of the steel strip supplied in coils is allowed to be 50% greater than the value specified in Table 7, and the thickness deviation within 15m of the weld zone is allowed to be 60% greater than the value specified in Table 7. 5.1.3 Width Permissible Deviation
The width permissible deviation of the base material shall comply with the provisions of Table 8. 5.1.4 Allowable deviation of length
The allowable deviation of length of all base materials shall comply with the provisions of Table 9, Table 8 Allowable deviation of width
Nominal width
600~1200
>1200~1500
Nominal length (L)
5.2 Appearance
5.2.1 Out-of-squareness
Grade A accuracy
Allowable deviation
Allowable deviation of length
Allowable deviation
Grade A accuracy
Grade B accuracy
Unit: mm
Unit: mm
The out-squareness of the steel plate shall not exceed 1% of the nominal width of the steel plate. The squareness of the steel plate is the vertical projection length of the wide side of the steel plate in the rolling direction, or half of the difference in the diagonal length of the steel plate. 5.2.2 Cutter bend
The sickle bend of the steel plate and the steel strip shall comply with the provisions of Table 10. Table 10 Permissible deviation of sickle bend
Maximum value of cutter bend
Measurement length
Unit is millimeter
Actual length (L)
GB/T2518—2004
5.2.3 Unevenness
The unevenness of the steel plate shall comply with the provisions of Table 11. The unevenness of the steel plate is the maximum distance between the lower surface of the steel plate and the platform when the steel plate is placed freely on the platform.
Table 11 Allowable deviation of unevenness of steel plate
Allowable deviation of unevenness
Performance level code
Nominal thickness
>0.7~<1.2
≥0.7~<1.2
Note: There is no requirement for unevenness deviation for grades 400, 450 and 550. <1200
5.3 The inner diameter and outer diameter (maximum value) of steel strip supplied in coils shall be specified in the contract. Nominal width
≥1200~<1500
Unit: mm
5.4 Weight
The weight of steel plate can be delivered by actual weight or theoretical weight. The calculation method of theoretical weight is shown in Appendix A. Steel strip is delivered by actual weight. Order Content
6.1 The order contract or order shall include the following: a)
Product name (plate or strip):
Standard number of this product:
Type of steel base;
Performance level;
Type and weight of coating,
Surface structure;
Surface treatment (passivation, oiling, lacquer sealing, phosphating or no treatment); surface quality,
Specifications and quantity;
Dimensional accuracy.
If the following information is not provided when ordering, the standard products will be processed in the conventional way: 6.2
Steel base type: products with original thickness <3.0mm are supplied as cold-rolled base plates, and products with thickness >3.0mm are supplied as hot-rolled base plates; a)
Surface treatment: except for alloying plating and smooth surface, passivation and oiling treatment are applied; b)
Surface structure: as unsmooth surface treatment: d) Dimensional accuracy: supplied as Class A accuracy; Packaging: as provided by the supplier. e
6.3 Marking example:
Marking order: standard number-performance level-coating type-zinc layer weight-surface structure-surface treatment-steel base type-specification size Galvanized steel sheet, mechanical bite grade, zinc coating, zinc layer weight 275g/m2, normal zinc flower polishing, surface treatment passivation and oiling, table (1)
Surface quality FB grade, cold rolled substrate, specification 2.0mm×1200mm×2000mm marking example: GB/T2518-02Z275-NS-CO-FB-2 .0X1200X2000(2)
Galvanized steel strip, 220 structural grade, zinc-iron alloy, zinc layer weight 180g/m2, zinc-iron alloy smooth, surface untreated, surface quality FA grade, hot-rolled base plate, specification 2.0mm×1200mm. The marking example is: GB/T2518-220ZF180-ZFS-U-FA-H2.0X1200XC Technical requirements
Production process
The production process of steel plates and steel strips is usually selected by the manufacturer. 7.2 Chemical composition
GB/T2518-2004
The chemical composition (melting analysis) of steel plates and steel strips shall comply with the provisions of Table 12. When required by the user, the analysis results shall be provided. Table 12
2 Chemical composition (melting analysis)
Energy level
Structural grade
Note 105 grade base material can also add appropriate amount of titanium, saw or vanadium. Chemical composition (mass fraction)/%
Note 2: Titanium of 06 grade can be replaced by saw or vanadium in whole or in part, and carbon and nitrogen should be completely solidified. Note 3: The phosphorus content of grade 350 and above is not more than 0.20%. 3 Zinc layer plate
The weight of zinc layer should comply with the provisions of Table 13.
Table 13 Zinc layer weight plate
Double-sided three-point detection
Layer type
Zinc-iron alloy
(ZF40)
(ZF180)
Note 1: The items in brackets in the table need to be agreed upon by both parties. Note 2: For steel strips divided by wide coils, only single-point inspection can be performed. Minimum average value/
(g/m2)
Not greater than
Minimum value of single point detection/(g/m)
GB/T2518--2004
7.4 Coating adhesion
Coating adhesion should be tested by 180° cold bending of zinc layer according to the diameter specified in Table 14. No zinc layer is allowed to fall off beyond 5mm from the edge of the specimen bend, but zinc layer cracks that do not expose the steel base are allowed to appear on the surface. Zinc-iron alloy (ZF) coating is allowed to have cracks, coarsening and powder. Table 14 180° cold bending test of zinc layer
Performance level
Plate thickness a/mm
Z275, ZF180
7.5 Mechanical properties
and below
Various thicknesses
<3.0/≥3.0
Bending center diameter (D)
320, 350
Various thicknesses
7.5.101~06 grade steel plates and steel strips The mechanical properties shall comply with the provisions of Table 15. When conducting a 180° cold bending test on a steel base, cracks and delamination are not allowed to appear at the bending portion of the specimen.
Table 1501~06 grade steel plate and strip mechanical properties Axomm/
Rpo.2/(N/mm)
140~300
140~260
140~270
120~280
Note 1, if the yield point is obvious, take R.
(N/mm）
270~500
270~420
270~380
270~350
270~350
Note 2: For tensile test, take transverse specimens, and the tensile strength value is incremented by 10N/mm. %
Not less than
Note 3: When the material thickness (after removing the galvanized layer) is 0.7mm, the elongation value listed in the table is reduced by 2. ngo
180° cold bending diameter of steel base
(d, transverse)
plate thickness (a)
Note 4: When the material thickness (after removing the galvanized layer) is ≤0.7mm, the r value of grade 06 in the table is reduced by 0.2 and the na value is reduced by 0.01. Note 5: When the material thickness (after removing the galvanized layer) is >1.5mm, the r value of grade 06 in the table is reduced by 0.2. Note 6: Grade 04 can also provide ngo and rg values, and the values are determined by negotiation between the supply and demand parties. Note 7: The mechanical properties of the hot-rolled base material are negotiated by the supply and demand parties. 9
≥3mm
GB/T2518—2004
Due to strain aging (the property that hardness increases and elongation decreases with the extension of storage time), the mechanical properties specified in Table 15 have applicable time periods as specified in Table 16 for steel plates and strips of various performance levels. To reduce this effect, 05 or 06 grade steel plates and strips should be used.
Applicable time period for mechanical properties
Applicable time period
1 month
6 months
6 months
The mechanical properties of structural grade steel plates and strips shall comply with the provisions of Table 17. The 180° cold bending test of steel base is only carried out when the user has special requirements7.5.2
. When conducting the bending test, cracks and delamination are not allowed to appear at the bending part of the specimen. Table 17 Mechanical properties of structural grade steel plates and strips Rpo.2/
(N/mm2）
Not less than
Note 1: If the yield point is obvious, take RH
(N/mm）
Not less than
Agomm/%
Not less than
Note 2: For the tensile test, take the transverse specimen, and the tensile strength value (for reference only) is rounded by 10N/mm2. Note 3 When the material thickness (after removing the galvanized layer) is ≤0.7mm, the elongation value listed in the table is reduced by 2. 7.6 Surface quality
The surface quality level and characteristics of steel plates and strips are shown in Table 18. 7.6.1
Table 18 Surface quality levels and characteristics
Surface quality level code
Ordinary surface
Higher surface
Commercial surface
180° bending diameter of steel base (d, transverse) Plate thickness (a)
≥3mm
Small corrosion spots, uneven zinc flower dark spots, slight scratches and indentations, air knife stripes, small passivation spots, etc. are allowed. Stretch straightening marks and zinc flow lines are allowed. There shall be no corrosion spots, but slight imperfect surfaces such as stretch straightening marks, finishing indentations, scratches, embossing, zinc flower patterns, zinc flow lines, slight passivation defects, etc. are allowed. The better side shall not have an adverse effect on the uniform appearance of the high-quality paint layer. The requirements for the other side shall not be lower than the surface level FB.
7.6.2 The surface quality of steel plates and steel strips with hot-rolled pickled coils as the base material is only FA. 7.6.3 Unless otherwise agreed by the supply and demand parties, only one side of the steel plates and steel strips with surface quality of FA or FB is inspected. Without special instructions, the outer surface of the steel strip and the upper surface of the steel plate are the inspection surfaces. 920%. 3 Zinc layer plate
The weight of the zinc layer shall comply with the provisions of Table 13.
Table 13 Zinc layer weight plate
Double-sided three-point detection
Layer type
Zinc-iron alloy
(ZF40)
(ZF180)
Note 1: The items in brackets in the table need to be agreed upon by both parties. Note 2: For steel strips divided from wide coils, only single-point inspection can be performed. Minimum average value/
(g/m2)
Not greater than
Minimum value of single-point inspection/(g/m)
GB/T2518--2004
7.4 Coating adhesion
The coating adhesion shall be subjected to a 180° cold bending test of the zinc layer according to the diameter specified in Table 14. The zinc layer is not allowed to fall off beyond 5mm from the edge of the specimen bend, but zinc layer cracks that do not expose the steel base are allowed to appear on the surface. The zinc-iron alloy (ZF) coating is allowed to have cracks, coarsening and powder. Table 14 180° cold bending test of zinc layer
Performance level
Plate thickness a/mm
Z275, ZF180
7.5 Mechanical properties
and below
Various thicknesses
<3.0/≥3.0
Bending center diameter (D)
320, 350
Various thicknesses
7.5.101~06 grade steel plates and steel strips The mechanical properties shall comply with the provisions of Table 15. When conducting a 180° cold bending test on the steel base, cracks and delamination are not allowed to appear at the bend of the specimen.
Table 1501~06 grade steel plate and strip mechanical properties Axomm/
Rpo.2/(N/mm)
140~300
140~260
140~270
120~280
Note 1, if the yield point is obvious, take R.
(N/mm）
270~500
270~420wwW.bzxz.Net
270~380
270~350
270~350
Note 2: For tensile test, take transverse specimens, and the tensile strength value is incremented by 10N/mm. %
Not less than
Note 3: When the material thickness (after removing the galvanized layer) is 0.7mm, the elongation value listed in the table is reduced by 2. ngo
180° cold bending diameter of steel base
(d, transverse)
plate thickness (a)
Note 4: When the material thickness (after removing the galvanized layer) is ≤0.7mm, the r value of grade 06 in the table is reduced by 0.2 and the na value is reduced by 0.01. Note 5: When the material thickness (after removing the galvanized layer) is >1.5mm, the r value of grade 06 in the table is reduced by 0.2. Note 6: Grade 04 can also provide ngo and rg values, and the values are determined by negotiation between the supply and demand parties. Note 7: The mechanical properties of the hot-rolled base material are negotiated by the supply and demand parties. 9
≥3mm
GB/T2518—2004
Due to strain aging (the property that hardness increases and elongation decreases with the extension of storage time), the mechanical properties specified in Table 15 have applicable time periods as specified in Table 16 for steel plates and strips of various performance levels. To reduce this effect, 05 or 06 grade steel plates and strips should be used.
Applicable time period for mechanical properties
Applicable time period
1 month
6 months
6 months
The mechanical properties of structural grade steel plates and strips shall comply with the provisions of Table 17. The 180° cold bending test of steel base is only carried out when the user has special requirements7.5.2
. When conducting the bending test, cracks and delamination are not allowed to appear at the bending part of the specimen. Table 17 Mechanical properties of structural grade steel plates and strips Rpo.2/
(N/mm2）
Not less than
Note 1: If the yield point is obvious, take RH
(N/mm）
Not less than
Agomm/%
Not less than
Note 2: For the tensile test, take the transverse specimen, and the tensile strength value (for reference only) is rounded by 10N/mm2. Note 3 When the material thickness (after removing the galvanized layer) is ≤0.7mm, the elongation value listed in the table is reduced by 2. 7.6 Surface quality
The surface quality level and characteristics of steel plates and strips are shown in Table 18. 7.6.1
Table 18 Surface quality levels and characteristics
Surface quality level code
Ordinary surface
Higher surface
Commercial surface
180° bending diameter of steel base (d, transverse) Plate thickness (a)
≥3mm
Small corrosion spots, uneven zinc flower dark spots, slight scratches and indentations, air knife stripes, small passivation spots, etc. are allowed. Stretch straightening marks and zinc flow lines are allowed. There shall be no corrosion spots, but slight imperfect surfaces such as stretch straightening marks, finishing indentations, scratches, embossing, zinc flower patterns, zinc flow lines, slight passivation defects, etc. are allowed. The better side shall not have an adverse effect on the uniform appearance of the high-quality paint layer. The requirements for the other side shall not be lower than the surface level FB.
7.6.2 The surface quality of steel plates and steel strips with hot-rolled pickled coils as the base material is only FA. 7.6.3 Unless otherwise agreed by the supply and demand parties, only one side of the steel plates and steel strips with surface quality of FA or FB is inspected. Without special instructions, the outer surface of the steel strip and the upper surface of the steel plate are the inspection surfaces. 920%. 3 Zinc layer plate
The weight of the zinc layer shall comply with the provisions of Table 13.
Table 13 Zinc layer weight plate
Double-sided three-point detection
Layer type
Zinc-iron alloy
(ZF40)
(ZF180)
Note 1: The items in brackets in the table need to be agreed upon by both parties. Note 2: For steel strips divided from wide coils, only single-point inspection can be performed. Minimum average value/
(g/m2)
Not greater than
Minimum value of single-point inspection/(g/m)
GB/T2518--2004
7.4 Coating adhesion
The coating adhesion shall be subjected to a 180° cold bending test of the zinc layer according to the diameter specified in Table 14. The zinc layer is not allowed to fall off beyond 5mm from the edge of the specimen bend, but zinc layer cracks that do not expose the steel base are allowed to appear on the surface. The zinc-iron alloy (ZF) coating is allowed to have cracks, coarsening and powder. Table 14 180° cold bending test of zinc layer
Performance level
Plate thickness a/mm
Z275, ZF180
7.5 Mechanical properties
and below
Various thicknesses
<3.0/≥3.0
Bending center diameter (D)
320, 350
Various thicknesses
7.5.101~06 grade steel plates and steel strips The mechanical properties shall comply with the provisions of Table 15. When conducting a 180° cold bending test on the steel base, cracks and delamination are not allowed to appear at the bend of the specimen.
Table 1501~06 grade steel plate and strip mechanical properties Axomm/
Rpo.2/(N/mm)
140~300
140~260
140~270
120~280
Note 1, if the yield point is obvious, take R.
(N/mm）
270~500
270~420
270~380
270~350
270~350
Note 2: For tensile test, take transverse specimens, and the tensile strength value is incremented by 10N/mm. %
Not less than
Note 3: When the material thickness (after removing the galvanized layer) is 0.7mm, the elongation value listed in the table is reduced by 2. ngo
180° cold bending diameter of steel base
(d, transverse)
plate thickness (a)
Note 4: When the material thickness (after removing the galvanized layer) is ≤0.7mm, the r value of grade 06 in the table is reduced by 0.2 and the na value is reduced by 0.01. Note 5: When the material thickness (after removing the galvanized layer) is >1.5mm, the r value of grade 06 in the table is reduced by 0.2. Note 6: Grade 04 can also provide ngo and rg values, and the values are determined by negotiation between the supply and demand parties. Note 7: The mechanical properties of the hot-rolled base material are negotiated by the supply and demand parties. 9
≥3mm
GB/T2518—2004
Due to strain aging (the property that hardness increases and elongation decreases with the extension of storage time), the mechanical properties specified in Table 15 have applicable time periods as specified in Table 16 for steel plates and strips of various performance levels. To reduce this effect, 05 or 06 grade steel plates and strips should be used.
Applicable time period for mechanical properties
Applicable time period
1 month
6 months
6 months
The mechanical properties of structural grade steel plates and strips shall comply with the provisions of Table 17. The 180° cold bending test of steel base is only carried out when the user has special requirements7.5.2
. When conducting the bending test, cracks and delamination are not allowed to appear at the bending part of the specimen. Table 17 Mechanical properties of structural grade steel plates and strips Rpo.2/
(N/mm2）
Not less than
Note 1: If the yield point is obvious, take RH
(N/mm）
Not less than
Agomm/%
Not less than
Note 2: For the tensile test, take the transverse specimen, and the tensile strength value (for reference only) is rounded by 10N/mm2. Note 3 When the material thickness (after removing the galvanized layer) is ≤0.7mm, the elongation value listed in the table is reduced by 2. 7.6 Surface quality
The surface quality level and characteristics of steel plates and strips are shown in Table 18. 7.6.1
Table 18 Surface quality levels and characteristics
Surface quality level code
Ordinary surface
Higher surface
Commercial surface
180° bending diameter of steel base (d, transverse) Plate thickness (a)
≥3mm
Small corrosion spots, uneven zinc flower dark spots, slight scratches and indentations, air knife stripes, small passivation spots, etc. are allowed. Stretch straightening marks and zinc flow lines are allowed. There shall be no corrosion spots, but slight imperfect surfaces such as stretch straightening marks, finishing indentations, scratches, embossing, zinc flower patterns, zinc flow lines, slight passivation defects, etc. are allowed. The better side shall not have an adverse effect on the uniform appearance of the high-quality paint layer. The requirements for the other side shall not be lower than the surface level FB.
7.6.2 The surface quality of steel plates and steel strips with hot-rolled pickled coils as the base material is only FA. 7.6.3 Unless otherwise agreed by the supply and demand parties, only one side of the steel plates and steel strips with surface quality of FA or FB is inspected. Without special instructions, the outer surface of the steel strip and the upper surface of the steel plate are the inspection surfaces. 92
before the test. When the bending test is carried out, cracks and delamination are not allowed to appear at the bending part of the specimen. Table 17 Mechanical properties of structural grade steel plates and strips Rpo.2/
(N/mm2）
Not less than
Note 1: If the yield point is obvious, take RH
(N/mm）
Not less than
Agomm/%
Not less than
Note 2: For the tensile test, take a transverse specimen, and the tensile strength value (for reference only) is incremented by 10N/mm2. Note 3 When the material thickness (after removing the galvanized layer) is ≤0.7mm, the elongation value listed in the table is reduced by 2. 7.6 Surface quality
The surface quality level and characteristics of steel plates and strips are shown in Table 18. 7.6.1
Table 18 Surface quality levels and characteristics
Surface quality level code
Ordinary surface
Higher surface
Commercial surface
180° bending diameter of steel base (d, transverse) Plate thickness (a)
≥3mm
Small corrosion spots, uneven zinc flower dark spots, slight scratches and indentations, air knife stripes, small passivation spots, etc. are allowed. Stretch straightening marks and zinc flow lines are allowed. There shall be no corrosion spots, but slight imperfect surfaces such as stretch straightening marks, finishing indentations, scratches, embossing, zinc flower patterns, zinc flow lines, slight passivation defects, etc. are allowed. The better side shall not have an adverse effect on the uniform appearance of the high-quality paint layer. The requirements for the other side shall not be lower than the surface level FB.
7.6.2 The surface quality of steel plates and steel strips with hot-rolled pickled coils as the base material is only FA. 7.6.3 Unless otherwise agreed by the supply and demand parties, only one side of the steel plates and steel strips with surface quality of FA or FB is inspected. Unless otherwise specified, the outer surface of the steel strip and the upper surface of the steel plate are the inspection surfaces. 92
before the test. When the bending test is carried out, cracks and delamination are not allowed to appear at the bending part of the specimen. Table 17 Mechanical properties of structural grade steel plates and strips Rpo.2/
(N/mm2）
Not less than
Note 1: If the yield point is obvious, take RH
(N/mm）
Not less than
Agomm/%
Not less than
Note 2: For the tensile test, take a transverse specimen, and the tensile strength value (for reference only) is incremented by 10N/mm2. Note 3 When the material thickness (after removing the galvanized layer) is ≤0.7mm, the elongation value listed in the table is reduced by 2. 7.6 Surface quality
The surface quality level and characteristics of steel plates and strips are shown in Table 18. 7.6.1
Table 18 Surface quality levels and characteristics
Surface quality level code
Ordinary surface
Higher surface
Commercial surface
180° bending diameter of steel base (d, transverse) Plate thickness (a)
≥3mm
Small corrosion spots, uneven zinc flower dark spots, slight scratches and indentations, air knife stripes, small passivation spots, etc. are allowed. Stretch straightening marks and zinc flow lines are allowed. There shall be no corrosion spots, but slight imperfect surfaces such as stretch straightening marks, finishing indentations, scratches, embossing, zinc flower patterns, zinc flow lines, slight passivation defects, etc. are allowed. The better side shall not have an adverse effect on the uniform appearance of the high-quality paint layer. The requirements for the other side shall not be lower than the surface level FB.
7.6.2 The surface quality of steel plates and steel strips with hot-rolled pickled coils as the base material is only FA. 7.6.3 Unless otherwise agreed by the supply and demand parties, only one side of the steel plates and steel strips with surface quality of FA or FB is inspected. Without special instructions, the outer surface of the steel strip and the upper surface of the steel plate are the inspection surfaces. 9
Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.