Metallic coatings--Hot dip galvanized coatings on fabricated iron and steel articles--Specifications and test methods
Some standard content:
ICS 25. 220. 40
National Standard of the People's Republic of China
GB/T 13912—2002
Replaces GB/T 13912—1992
Metallic Coatings
Hot-dip Galvanized Coatings on Steel Articles
Technical Requirements and Test Methods
Metallic Coatings-Hot dip galvanized coatings on fabricated iron and steel articles--Specifications and test methods(ISO 1461:1999,Hot dip galvanized coatings on fabricated iron and steel articles--Specifications and test methods,MOD)Promulgated on April 10, 2002
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
Implementation on December 1, 2002
GB/T 13912—2002
Normative references
3 Terms and definitions
General requirements
Information that the purchaser should provide to the supplier
Base metal
Hot-dip galvanizing bath
Requirements for coating
Leakage and repair
Adhesion
Acceptance criteria
7 Test methods
7.1 Appearance test
Coating thickness test
7.3 Negative force test
8 Qualification certificates
|.+.+.+.
Appendix A (Informative Appendix) Comparison of the chapter and article numbers of this standard with those of ISO) 1461:1999 Appendix B (Informative Appendix)
Appendix C (Informative Appendix)
Appendix [(Normative Appendix)
Appendix F (Informative Appendix)
References
Technical differences between this standard and ISO146]:1999 and their causes Influence of hot-dip galvanizing
Safety requirements
Thickness determination
GB/T 13912—2002
This standard modifies and adopts [ISO1461:1999 "Technical conditions and test methods for hot-dip galvanizing layer of steel products". This standard is redrafted based on ISO1461:1999. Appendix A lists the comparison table of the factory standard and ISO1461 article numbers.
This standard makes the following modifications to ISO1461:1999. Appendix B lists the technical differences between this standard and ISO1461 and their origins.
According to the existing domestic series of standards, the name of the standard is changed to "Technical requirements and test methods for hot-dip galvanizing of metal-coated steel products":
The foreword of ISO 1461 is cancelled;
-"This standard" is used instead of "this international standard"; some Chinese standards that adopt international standards are quoted; the contents of 4.2 and Appendix A in ISO1461:1999 are combined into 4.1 of this standard; the contents of Chapter 6 in ISO1461:1999 are decomposed into Chapters 6 and 7 of this standard, which puts forward requirements for the coating thickness of hot-dip galvanized parts that use zinc explosion instead of centrifugal treatment or zinc explosion and centrifugal treatment at the same time;
Safety requirements are put forward for hot-dip galvanizing of parts that have not been completely dried. This standard replaces GB/T13912-1992 "Technical requirements for hot-dip galvanized layers of steel products with metal coatings". The main changes of this standard compared with GR/T13912-1992 are as follows: Under the condition that the thickness of the coating is greater than the specified value, dark or light gray color unevenness is allowed on the surface of the plated parts; safety requirements are put forward for the hot-dip galvanizing production process; the area of each plated surface should not exceed 10 cm2; the thickness of the repair layer should be more than 30um thicker than the minimum thickness required for the galvanized layer: Appendix D of this standard is a normative appendix, and Appendix A, Appendix B, Appendix C and Appendix E are informative appendices. This standard is proposed by the China Machinery Industry Federation. This standard is under the jurisdiction of the National Technical Committee for the Promotion of Metal and Non-metallic Coverings. The responsible drafting unit of this standard is: Wuhan Materials Protection Research Institute. The participating drafting unit of this standard is: Harbin Tower Factory. The main drafters of this standard are: Wu Yong and Li Chunyan. I
GB/T139122002
Technical requirements and test methods for hot-dip galvanized layer of steel products
1 Scope
This standard specifies the technical requirements and test methods for hot-dip galvanized layer of steel products (the total content of other metal elements does not exceed 2%). This standard is not applicable to the following situations:
a) Plates, strips, wires, pipes and bars produced by continuous hot-dip galvanizing, b) Hot-dip galvanized products using special standards; d) Hot-dip galvanized products with additional requirements or inconsistent with the requirements of this standard. Note: The labels of these products can specify the hot-dip galvanized layer of the product by citing this label number or modifying some clauses of this standard. This standard does not specify the post-treatment and additional protective coating of hot-dip galvanized products. 2 Normative references
The clauses in the following documents become the clauses of this standard through reference in this standard. For all referenced documents with dates, all subsequent amendments (excluding errata) or revisions are applicable to this standard. However, the parties who reach an agreement based on this standard are encouraged to study whether the latest versions of these documents can be used. For all referenced documents without dates, the latest versions are applicable to this standard. GB/T 470 zinc chain (eqvISO 752)
Metallic coating thickness measurement anodic dissolution coulometric method (eqv1S02177)GB/T 4955
GB/T 4956
GB/T 6162
G3/T 9793
Measurement of thickness of non-magnetic coatings on magnetic metals by magnetic method (eqv1SO2178)Method for microscopic measurement of cross-sectional thickness of metal and oxide coatings (eqv1S0)1463)Metallic and other inorganic coatings thermal spraying zinc and its alloys (eqvISO2063)Metallic and other inorganic coatings on thickness measurement definitions and general rules (eqvISO2064)GB/T 12334
GB/T 13825
GB3/T 18253
ISO 2859 1
Metallic coverings - Determination of quality of hot-dip galvanized coating on ferrous metal materials - Methods for determination of quality of hot-dip galvanized coating on ferrous metal materials (nqISO1460) Types of inspection documents for steel and steel products (eyvIS0)10747) Sampling procedures for inspection of characteristics - Part 1: Sampling plan for inspection of lots according to the acceptable quality level (AQI.)
Sampling procedures for inspection of characteristics - Part 3: Sampling procedures for discontinuous lots IS0 2859-3±
3 Terms and definitions
The terms and definitions established in GB/T 12334 and the following apply to this standard. 3.1
Hot dip galvanizing
The process and method of immersing pre-treated steel or iron parts into a molten zinc bath to form a zinc and (or) zinc-iron alloy coating on their surface.
Hot dip galvanizing coatingThe zinc and (or) zinc-iron alloy coating obtained on the surface of steel parts by hot dip galvanizing; referred to as coating in this standard.
GB/T 13912—2002
Coating mass
Steel surface 1. The total mass of zinc and (or) zinc-iron alloy coating per unit area, expressed in g/m\. 3.4
Coating thickness
The total thickness of zinc and (or) zinc-iron alloy coating on the surface of steel, expressed in um. 3.5
Significant surface
The surface of the part that is hot-dip galvanized or will be hot-dip galvanized. The coating on this surface is extremely important for the appearance and (or) performance of the part.
Control sample
The hot-dip galvanized part or part group randomly selected from the inspection batch for testing. 3.7
Reference area
The area for testing at the specified number of times. 3.8
Local coating thickness local coating thickness The arithmetic mean value of the coating thickness measured by the magnetic method at a certain basic measurement surface for a specified number of times, or the converted value of the thickness of the coating mass of the galvanized layer measured by the weighing method for a specified number of times. 3.9
Mean coating thickness
The arithmetic mean value of the local thickness of the galvanized layer measured after sampling a certain large piece or a batch of galvanized pieces. Note: In this standard, large pieces refer to pieces with a surface area of more than 2m2 (see 6.2.7.2): 3.10
Local coating mass of the coating The coating mass of a certain area measured by the weighing method for a single measurement. 3.11
Mean toating mass of the coating The arithmetic half-mean value of the coating mass of the entire coating measured by the weighing method according to the provisions of Chapter 5, or the converted value of the average coating thickness. 3.12
Minimum valueminimum value
The minimum value of the converted value of the coating thickness measured by the weighing method on the basic measuring surface, or the minimum value of the arithmetic mean of the coating thickness measured by the magnetic method at a specified number of times. 3.13
Inspection lot
Referred to as lot. Refers to the hot-dip galvanized parts of a single order or delivery. 3.14
Acceptance inspectionacueptanceinspectionIn the absence of other provisions, it should be inspected on the hot-dip galvanized parts of the inspection lot within the hot-dip galvanizing manufacturer. 3.15
Uncatcdreas
The area on the surface of the steel product that does not react with the molten zinc. 2
4 General requirements
4.1 Information that the purchaser should provide to the supplier
4.1.1 Necessary information
Standard number of this standard.
4.1.2 Additional information
If the purchaser has special requirements, the following information should be provided: a) Chemical composition and properties of the base metal that will affect hot-dip galvanizing (see Appendix C); b) Marking of the main surface, which can be marked with drawings or samples with appropriate markings; GB/T13912—2002
c) Whether the surface is flat or not, the area that will affect the usability of the galvanized parts should be marked with drawings or other methods. These unevenness is often caused by zinc nodules formed during the galvanizing process, traces formed by the contact between the parts during galvanizing, etc. The supply and demand parties should negotiate to resolve Solve these problems;
Use samples or other methods to illustrate the required surface smoothness of the product; e) Are there any special pretreatment requirements:
Are there any special coating thickness requirements (see the notes in 6.2 and Appendix C) f)
Is it allowed that the coating thickness after centrifugal or blasting zinc treatment reaches the requirements of Table 3 instead of Table 2? Is it necessary to carry out post-treatment or painting after hot-diffusion galvanizing (see 5.2.3, Appendix C.4 and Appendix C.5); h)
Sampling method (see Chapter 5):
j) Is the certificate of conformity required to be consistent with the provisions of GB/T18253? The supplier shall provide relevant information including the repair method (see 6.3.2 and Appendix C.5) according to the requirements of the purchaser. 4.2 Base metal
The chemical composition, surface condition of the base metal, the weight of the product and the galvanizing conditions will affect the appearance, thickness, structure and physical/mechanical properties of the coating. This standard does not put forward specific requirements for these. The supply and demand parties can refer to Appendix C for consultation on the selection of base metal and galvanizing conditions.
4.3 Hot Sea Galvanizing Bath
The zinc bath used for hot dip galvanizing should mainly consist of molten zinc liquid. The total impurity content (excluding iron and tin) in the molten zinc should not exceed 1.5 of the total mass. The impurities referred to are specified in GB/T470. 4.4 Safety
Safety measures should be taken in accordance with the requirements of Appendix D during the production process of hot dip galvanizing. Note: IS14713 gives a guide for the selection of hot dip galvanized layers in Guanggang. 1SO12944-5 contains information on coatings applied over hot-dip galvanized iron (see Appendix).
5 Sampling
Samples for coating thickness tests shall be randomly selected from each inspection batch (see 3.6). Not less than the minimum number of articles shall be selected from the inspection batch in accordance with the requirements of Table 1 to form the sample. The sample size shall be determined according to the size of the batch
Table 1
Number of articles in inspection batch
501~1 200
1 201-*3 200
3 201-~10 000
>10 000
Minimum number of articles required for sample
GB/T 13912:2002bzxZ.net
Unless otherwise specified by the purchaser at the time of ordering, acceptance inspection shall be carried out before the products leave the galvanizing plant. 6 Requirements for coating
6.1 Appearance
The main surface (see 3.5) of all hot-dip galvanized parts shall be smooth, free of nodules, roughness and zinc thorns (if these zinc thorns may cause damage), peeling, non-plating, and residual slag. There shall be no zinc nodules and zinc embedding in the parts that may affect the use or corrosion resistance of the hot-dip galvanized parts.
Note 1: "Rough" and "smooth" are relative concepts. The roughness of the coating on the workpiece is different from the roughness of the zinc-cut products (such as galvanized steel sheets and zinc-sensitive steel wires) that have been mechanically rolled or (and) blown or smeared.
As long as the thickness of the coating is greater than the specified value, dark or light gray color uneven areas are allowed to exist on the surface of the plated workpiece. Galvanized workpieces stored under humid conditions are allowed to have white rust (white or charcoal-colored corrosion products with basic zinc oxide as the main component) on the surface. Note 2: It is impossible to establish a definition of appearance and finish that can cover all practical requirements. The appearance is checked monthly. The unqualified parts should be repaired or re-plated according to 6.3.2 and then sent for re-inspection. If there are special requirements (for example, galvanizing requires painting), samples should be provided as required (see 4.1.2 and Appendix C.1.4). 6.2 Thickness The coating thickness test shall be carried out by sampling in accordance with the number specified in Chapter 1 and by the test method specified in 7.2. According to the size of the main surface (see 3.5) of the hot-dip galvanized product, the coating thickness measured in the test shall meet the following requirements: a) For products (i.e. large products) with a main surface (see 3.5) area greater than 2m2, the average coating thickness measured in all basic measuring surfaces (see 3.7) of each product of the sample shall not be less than the minimum value of the corresponding average coating thickness in Table 2 or Table 3; h) For products with a main surface (see 3.5) area less than or equal to 2m2, the local coating thickness measured in each basic measuring surface (see 3.7) shall not be less than the local minimum value in Table 2 or Table 3: The average coating thickness measured in all basic measuring surfaces (see 3.7) of the sample shall not be less than The corresponding minimum average thickness in Table 2 or Table 3. Note: The length of the anti-corrosion time of the hot-dip galvanized layer is roughly proportional to the thickness of the layer. For parts that serve under extremely severe corrosion conditions and (or) require a longer service time, the coating thickness requirements can be higher than the requirements specified in this standard. However, the thickness of the galvanized layer is limited by factors such as the chemical composition of the substrate, the surface condition of the part, the geometric dimensions of the part, and the hot-dip galvanizing process parameters. When a thicker coating is required, the supply and demand parties should explore the technical feasibility of hot-dip galvanizing and indicate the relevant technical conditions (see Appendix C). Table 2 Minimum coating thickness without centrifugal treatment Parts and their thickness/rm
Steel thickness 6
3Steel thickness 6
1.5Steel thickness 3
Steel thickness, 5
Cast iron thickness ≥6||tt ||Thickness of cast iron3
Local thickness of coating/μm
Average thickness of coating/μm
Note: This table is for general requirements. Specific product standards may include various requirements including different thickness grades and classifications. In the case of no conflict with this standard, thicker coating requirements and other requirements may be added. Parts and their thickness/mm
Table 3 Minimum thickness of coating after centrifugation Local thickness of coating/μm
Diameter ≥20
Threaded parts
Other parts
(including cast iron parts)
6≤Diameter 20
Diameter 6
Original thickness 23
Sequence thickness 3
Note i This table is for general requirements. Fasteners and specific product standards may have different requirements (see 4.1.2.). Note 2: For galvanized parts that use zinc blasting instead of centrifugal treatment or zinc blasting and centrifugal treatment, see Appendix C.4. 6.3 Missing plating and repair
6.3.1 Missing plating
GB/T13912—2002
Average thickness of coating/jrm
The total area of the missing plating surface of the hot-dip galvanized part shall not exceed 0.0 ...5. The area of each missing galvanizing surface should not exceed 10 cm2. When there is no other agreement between the supply and demand parties, if the plating area is larger than the above specified value, these parts should be re-plated. 6. 3.2 Repair
If there is a missing galvanizing surface on the surface of hot-dip galvanized parts, the missing galvanizing surface should be repaired by hot-spraying zinc, zinc-rich paint or melting zinc alloy (see Appendix C.5). Unless the purchaser has special requirements, such as: hot-dip galvanizing is to be followed by painting or the thickness of the repair layer must be the same as the thickness of the original galvanized layer. The thickness of the zinc coating (covering) layer in the repair area should generally be 30% thicker than the corresponding local thickness of the coating required in Table 2 or Table 3. The repaired layer should be more than m, and it should be able to provide sacrificial anode protection to the steel during the use of the steel. Before repair, the scale and other dirt in the missed plating area should be removed, or other pre-treatment methods should be used to ensure the adhesion between the repair layer and the substrate. If hot-spraying zinc repair is used, it should be carried out in accordance with GB/T9793. The supplier should inform the buyer of the repair method. If the buyer has special requirements, the supplier should be asked to inform the repair method before repair. For the repair method of the damaged surface, please refer to Appendix 5. 6.4 Adhesion
…·Hot-dip galvanized workpieces of normal thickness should not have peeling and flaking under normal working conditions. The puncture and flaking of the coating caused by bending and deformation after galvanizing does not mean that the adhesion of the coating is poor. If the buyer has special requirements and must test the adhesion, it will be negotiated by the supplier and the buyer. 6.5 Acceptance criteria
Select the following basic measurement surfaces according to the requirements of 7.2.2, and test them according to the provisions of 7.2.3 on these basic measurement surfaces. The test method is used for testing, and the measured coating thickness should not be less than the values specified in Table 2 and Table 3. Non-destructive test methods should be used unless there is a dispute or the supplier allows cutting of its products for weighing test. When the steel thickness of the products is different, the products of each thickness range should be regarded as a separate processing batch, and their coating thickness should be respectively patrolled to the corresponding values in Table 2 and Table 3. If the coating thickness of the sample does not meet these requirements, double sampling should be taken from the batch of products (if the number of products is less than the minimum sampling number, all products should be tested). If this larger sample passes the test, the batch of products is considered qualified; if it fails, the products that do not meet the requirements should be scrapped or re-plated with the permission of the purchaser.
7 Test method
7.1 Appearance test
Use corrected vision to check orally under normal reading environment, 7.2 Coating thickness test
7.2.1 General test conditions
GB/T 13912—2002
When the size of the article permits, the thickness of the coating shall not be measured in an area less than 10 mm from the edge, on the flame-cut surface or in the corner (see Annex C.1.2).
7.2.2 Basic measuring plane (see 3.7)
In order to obtain the most representative average thickness of the coating (see 3.9) or the coating amount (see 3.11), the number, position and size of the basic measuring plane when measuring the thickness of the coating by magnetic or gravimetric method shall be determined according to the shape and size of the article. For the longer articles in the sample, the basic measuring plane shall be obtained at a position approximately [0 mm] from each end, roughly close to the center line, and shall include the entire cross-section of the article. The number of basic measuring surfaces depends on the size of each workpiece in the sample and should be determined according to the following provisions: a) For workpieces with a rough surface (see 3.5) area greater than 2m (i.e. large workpieces), at least 3 basic measuring surfaces should be taken for each workpiece in the sample; b) For workpieces with a main surface (see 3.5) area greater than 10000mm~2m (including 2m), at least one basic measuring surface should be taken for each small workpiece in the sample; c) For workpieces with a main surface (see 3.5) area of 1000mm~10000mm (including 10000mm), one basic measuring surface should be taken for each workpiece in the sample; d) For workpieces with a main surface (see 3.5) area less than 100 The total number of basic measuring surfaces shall be taken according to the last column of Table 1. Therefore, the total number of pieces used for measurement is equal to the number of pieces required to provide a single basic measuring surface multiplied by the number provided in the last column of Table 1. This number is related to the size of the inspection batch (see 3.13) (if the batch is not large, all the pieces can be taken for testing). If the above provisions are not adopted, the sampling procedure specified in IS () 2859-1 or ISO2859-3 can also be used. Note: 10000mm2 = 100cm
1 000 mm\--10 cn
2m is typically expressed as 200c×1c0cm
100001nm is typically expressed as 10cm×10cm1(100)mm is typically expressed as 1cm×icm7.2.3 Thickness measurement method (see Appendix E) The thickness of the coating can be measured by the following methods: a) The weighing method is an arbitration method and is carried out in accordance with the requirements of GI3/T13825. The zinc coating thickness measured by this method should be converted into the coating thickness according to the density of the coating (7.2g/cm\) (see Appendix E.2). This method is a destructive test method. In the case of less than 10 pieces, if the weighing method may involve damage to the parts and the resulting remedial costs are unacceptable to the purchaser, the purchaser should not reluctantly accept the weighing method.
b) The magnetic method is a non-destructive test method and is carried out in accordance with the requirements of GB/T4956. When measuring, the basic measuring surface should be placed in a typical area that can be selected as the basic measuring surface by the weighing method. When the magnetic method is used to measure the thickness in each basic measuring surface not less than 1000mm, at least 5 measuring points should be taken for thickness measurement, and the arithmetic average value is the local thickness of the coating on the basic measuring surface (see 3.9). As long as the average value is not lower than the value required for the local thickness in Table 2 or Table 3, the measured value at an individual measuring point is allowed to be lower than the value in Table 2 or Table 3. The magnetic method is most suitable for reverse online quality control in the factory. Since each area measured by this method is very small, the individual measurement value may be lower than the local thickness or average thickness value of the coating. If a sufficient number of measurements are made in a basic measuring surface by the magnetic method, the measured local thickness value is close to the value measured by the weighing method. c) The cross-sectional microscopy method is a destructive test method and represents only a certain point, so it is not suitable for routine inspection of large or valuable parts. We can observe the metallographic structure of a certain point in accordance with the requirements of GB/T6462. d) Anodic dissolution coulometric method is a destructive test method, which is carried out in accordance with the requirements of GB/T4955. Note: Electromagnetic method can also be used, which is a non-destructive test method (see Appendix E.1). Among the above test methods, the destructive test method will cause damage to the hot-dip galvanized parts. In general, non-destructive test methods should be used. If there is a dispute, the weighing method should be used for arbitration. If the part is very small, the sum of the main surface areas of more than 5 parts must reach 1000mm. Under the condition that each part has a basic measuring surface suitable for the magnetic method, the magnetic method can be used. Otherwise, the weighing method should be used. For the conversion method of coating thickness and coating amount, please refer to Appendix F. 7.3 Adhesion test GB/T13912-2002 As long as the adhesion between the galvanized layer and the substrate can meet the requirements of the parts under use and general operating conditions, it is usually not necessary to specifically test the bonding strength between the galvanized layer and the substrate.
If the purchaser has special requirements, the test method of adhesion shall be determined by negotiation between the supply and demand parties (see Appendix C.6). The adhesion test shall be carried out on the main surface and in the area where adhesion is required during use. 8 Qualification certificate
As required, the hot-dip galvanizing manufacturer shall provide a certificate that meets the requirements of this standard. GB/T13912-2002
Appendix A
Informative Appendix)
Comparison table of chapter and article numbers of this standard with those of IS01461:1999 A.] gives a comparison table of chapter and article numbers of this standard with those of IS01461:1999. Table A.1 Comparison of the chapter and clause numbers of this standard with those of ISO 1461:1999 Chapter and clause numbers of this standard
Note to Chapter 4
Appendix C
D. 1 and D. 2
Appendix F
References
Corresponding chapter and clause numbers of ISO 1461
4.2 and Appendix A
Note 1 to Chapter 4
Note 2 to Chapter 1
Appendix B
Note: The chapter and clause numbers of this standard other than those in the table are the same as those of ISO 1461:1999 and the contents correspond. Appendix B
(Informative Appendix)
Technical differences between this standard and ISO 1461:1999 and their causes Table B.1 gives the differences between this standard and ISO 1461:1999.1999 Technical differences and their causes, Table B.1 Technical differences between this standard and IS0 1461:1999 and their causes Article number of this standard Technical differences For galvanized parts (see C.1) that use zinc blasting instead of centrifugal treatment or zinc blasting and centrifugal treatment at the same time, the coating thickness can refer to the requirements of Table 3. Measures are required to prevent splashing zinc liquid from injuring people. Original GB/T13912-2002 Many hot-dip galvanizing manufacturers in my country use zinc blasting and centrifugal drying. Many manufacturers in my country do not have a drying process before hot-dip galvanizing or the parts are not completely dried before hot-dip galvanizing. 9
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