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GB/T 9799-2024 PDF English


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GB/T 9799-2024English325 Add to Cart 0-9 seconds. Auto-delivery. Metallic and other inorganic coatings - Electroplated coatings of zinc with supplementary treatments on iron or steel Valid
GB/T 9799-2011English85 Add to Cart 0-9 seconds. Auto-delivery. Metallic and other inorganic coatings -- Electroplated coatings of zinc with supplementary treatments on iron or steel Obsolete
GB/T 9799-1997English319 Add to Cart 3 days Metallic coatings--Electroplated coatings of zinc on iron or steel Obsolete
GB/T 9799-1988EnglishRFQ ASK 3 days Metallic coatings--Electroplated coatings of zinc on iron or steel Obsolete
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GB/T 9799-2024: PDF in English (GBT 9799-2024)

GB/T 9799-2024 GB NATIONAL STANDARD OF THE PEOPLE'S REPUBLIC OF CHINA ICS 25.220.40 CCS A 29 Replacing GB/T 9799-2011 Metallic and other inorganic coatings - Electroplated coatings of zinc with supplementary treatments on iron or steel (ISO 2081.2018, MOD) ISSUED ON. JUNE 29, 2024 IMPLEMENTED ON. JANUARY 1, 2025 Issued by. State Administration for Market Regulation; Standardization Administration of PRC. Table of Contents Foreword... 3 Introduction... 5 1 Scope... 6 2 Normative references... 6 3 Terms and definitions, abbreviations and symbols... 8 3.1 Terms and definitions... 8 3.2 Abbreviations... 8 3.3 Symbols... 8 4 Information that the buyer shall provide to the supplier... 8 4.1 Necessary information... 8 4.2 Additional information... 9 5 Marking... 9 5.1 General rules... 9 5.2 Marking rules... 10 5.3 Marking of base materials... 11 5.4 Marking of heat treatment requirements... 11 6 Requirements... 12 6.1 Appearance... 12 6.2 Thickness... 12 6.3 Trivalent chromium conversion coating and other post-treatment... 13 6.4 Bonding strength of the zinc electroplated coating and the trivalent chromium conversion coating... 13 6.5 Accelerated corrosion test... 13 6.6 Stress relief heat treatment before electroplating... 14 6.7 Hydrogen embrittlement relief heat treatment... 15 7 Sampling... 15 Appendix A (normative) Marking of chromate conversion coatings and other auxiliary treatments... 16 Appendix B (normative) Measurement of average coating thickness on small workpieces... 18 References... 20 Metallic and other inorganic coatings - Electroplated coatings of zinc with supplementary treatments on iron or steel WARNING. Some of the substances and processes required by this document may cause health hazards if appropriate measures are not taken. This document does not discuss any matters and regulations that may endanger health, safety or the environment during the use of this document. Users of this document are responsible for establishing appropriate and feasible health, safety and environmental regulations and taking appropriate measures to comply with relevant national regulations. Compliance with this document does not mean exemption from legal obligations. 1 Scope This document specifies the requirements for treated zinc electroplated coatings on steel, including the information to be provided by the purchaser to the supplier and the requirements for heat treatment before and after electroplating. This document does not specify the surface condition of the base metal before zinc electroplating, but defects on the base metal surface will have an adverse effect on the appearance and performance of the coating. This document applies to treated zinc electroplated coatings on iron or steel. This document does not apply to. -- zinc electroplated coatings on unformed steel sheets, strips and wires; -- zinc electroplated coatings for tightly wound springs; -- zinc electroplated coatings for non-protective decorative purposes. The thickness of the electroplating coating on threaded parts can be limited by thread grade or assembly size requirements. 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 ISO 15724 Metallic and other inorganic coatings - Electrochemical measurement of diffusible hydrogen in steels - Barnacle electrode method 3 Terms and definitions, abbreviations and symbols 3.1 Terms and definitions The terms and definitions defined in GB/T 3138 and GB/T 12334 apply to this document. 3.2 Abbreviations The following abbreviations apply to this document. ER. hydrogen embrittlement relief heat treatment SR. stress relief heat treatment T2.organic sealant 3.3 Symbols The following symbols apply to this document. Fe. The chemical symbol for iron. Zn. The chemical symbol for zinc. 4 Information that the buyer shall provide to the supplier 4.1 Necessary information When ordering electroplated parts according to this document, the purchaser shall provide the following information in the contract or ordering agreement, or in writing on the engineering drawing. a) this document number GB/T 9799 and coating identification (see Chapter 5); b) the specified principal surfaces, e.g., by marking them on drawings or by providing samples with appropriate markings; c) the nature of the base metal, its surface condition and the type of finish (when these factors may affect the suitability and/or appearance of the electroplated coating) (see Chapter 1); d) the locations on the surface where insurmountable defects (hanger marks) are permitted (see 6.1); e) the type of finish, e.g., bright, matte or other finish, preferably together with an approved sample of the finish (see 6.1); f) the types of chromate conversion coating and other auxiliary treatments (see 6.3 and Appendix A); when the purchaser has special requirements, the chromate conversion coating shall be canceled, and non-traditional conversion coating and/or other auxiliary treatments, or paint-like coating treatments may be applied on the chromate conversion coating; g) the requirements for thickness and bonding strength tests (see 6.2, 6.4 and Appendix B); h) the tensile strength of the workpiece and requirements for heat treatment before and/or after electroplating (see 6.6 and 6.7); i) the sampling methods, acceptance levels or other inspection requirements (when inspection methods different from those specified in GB/T 12609 are used) (see Chapter 7); j) the requirements for accelerated corrosion testing (see 6.5) and rating (see 6.5.2). 4.2 Additional information The purchaser shall provide the supplier with the following additional information. a) special requirements or restrictions on the pretreatment of the workpiece to be plated (see [10] and [11] in References); b) other requirements, such as areas for testing and rating of workpieces of special shapes. 5 Marking 5.1 General rules The marking shall appear on the engineering drawing, purchase order, contract or detailed product description. The marking shall clearly identify, in the following order, where. A -- represents bright conversion coating; Y -- represents one of the other auxiliary treatment coating codes given in Table A.2. The chemical symbol of the base metal should be followed by the standard grade of the special alloy. For example, the UNS number of the special alloy, or the equivalent national or local number, can be indicated in the symbol < >. For example, Fe< G43400> is the UNS grade of a high-strength steel (see [12] in References). The following are examples of marking. EXAMPLE 1.The zinc electroplated coating of 12 μm thick on iron or steel (Fe), treated with bright chemical conversion (A) is marked as. Electroplated coating GB/T 9799-Fe/Zn12/A EXAMPLE 2.Same as EXAMPLE 1, but the workpiece is subjected to stress relief heat treatment before plating, with a minimum duration of 4 hours at 200 °C, marked as SR(200)≥4; for hydrogen embrittlement relief, it is heat treated at 190 °C for 8 hours after plating (before passivation), marked as ER(190)8; then, the coating is treated with bright chemical conversion (A) and sealed with an organic sealant (T2), and it is marked as. Electroplated coating GB/T 9799-Fe/SR(200)≥4/Zn12/ER(190)8/A/T2 5.3 Marking of base materials The base material shall be indicated by its chemical symbol. If it is an alloy, the main component shall be indicated, for example. a) Fe represents iron or steel; b) Zn represents zinc alloy; c) Al represents aluminum and aluminum alloys. 5.4 Marking of heat treatment requirements Heat treatment requirements shall be marked as follows. a) The letters SR represent the stress relief heat treatment before electroplating, and the letters ER represent the hydrogen embrittlement relief heat treatment after electroplating; b) The lowest temperature is indicated in degrees Celsius (°C) in parentheses; c) the duration of heat treatment, in hours (h). For example, SR(210)1 indicates that the stress relief heat treatment is carried out at 210 °C for 1 hour. 6 Requirements 6.1 Appearance This document does not specify the condition, finish or roughness of the base material prior to plating, but the appearance of the electroplated coating will depend on the surface condition of the base material (see [10] and [11] in References for surface preparation). The electroplated parts shall not have obvious coating defects such as blisters, pores, roughness, cracks or local absence of coating on the major surfaces, except for unavoidable coating defects caused by defects in the base metal. Contact marks on the workpiece are unavoidable and their location shall be agreed upon by the interested parties (see 4.1). The workpiece shall be clean and free from damage. Unless otherwise specified by the purchaser, the appearance of the zinc electroplated coating shall be bright. If necessary, the purchaser shall provide or confirm samples that can demonstrate the coating appearance requirements [see 4.1 e)]. 6.2 Thickness The coating thickness indicated in the marking shall be the minimum local thickness. Unless otherwise specified by the purchaser, the minimum local thickness shall be measured at any part of the main surface that can be contacted by a ball with a diameter of 20 mm (see 4.1 and 4.2). The methods specified in GB/T 6462, GB/T 4955, GB/T 4956, GB/T 11378, GB/T 16921 and GB/T 20018 are applicable to measuring the thickness of various zinc coatings on steel or iron. When there is a dispute over the thickness measurement, if the main surface area of the coating is greater than 100 mm2, it shall be measured according to the method specified in GB/T 6462; if the main surface area of the coating is less than 100 mm2, the average thickness of the coating shall be measured according to the method specified in Appendix B, and the minimum value of the average thickness of the coating can be regarded as the minimum local thickness of the coating. Before the thickness is measured according to the method specified in GB/T 4955, a soft abrasive, such as aluminum oxide grinding paste, shall be used to remove the chromate conversion coating, other conversion coating or organic coating. When the conversion coating is thick, the measurement result will be slightly lower. When the coating is rough or matte, the results obtained by the microscope method (see GB/T 6462) and the profile measurement method (see GB/T 11378) may be inaccurate. When being measured by the magnetic method, the thickness value measured for the rough or matte coating is larger than that for the smooth coating with the same mass per unit area. 6.3 Trivalent chromium conversion coating and other post-treatment When the purchaser specifically requests, the trivalent chromium conversion treatment may be canceled or replaced by other conversion treatments, such as chromium-free or phosphate conversion [see f) in 4.1]. The codes for trivalent chromium conversion and all other auxiliary treatments shall comply with the provisions of Appendix A. 6.4 Bonding strength of the zinc electroplated coating and the trivalent chromium conversion coating When the friction polishing test is carried out in accordance with GB/T 5270, the zinc electroplated coating shall continuously adhere to the base metal. The chromate conversion coating shall be subjected to the bonding strength test in accordance with the relevant provisions of GB/T 9791. All tests except the thickness test shall be carried out 24 hours after chromate conversion treatment. 6.5 Accelerated corrosion test 6.5.1 Neutral salt spray test The neutral salt spray test (NSS) specified in GB/T 10125 shall be carried out for the time specified in Table 1.The test surface shall be free of white rust and red rust when observed with the naked eye or corrected vision. Slight staining shall not be a reason for rejection. Some coating marks in Table 1 give the minimum local thickness of the zinc electroplated coating after chromate treatment under various service conditions. To ensure corrosion resistance, the thickness requirement of the coating depends on the severity of the service conditions. For example, the coating marked with Fe/Zn5 is only of the heat treatment process shall be indicated in the mark in accordance with the provisions of 5.2, 5.3 and 5.4. Steel parts with scale or dirt shall be cleaned before electroplating. For high-strength steel (tensile strength greater than or equal to 1000 MPa), chemical alkaline degreasing, anodic electrolytic degreasing or mechanical degreasing shall be used to avoid hydrogen embrittlement during the cleaning process (see [10] in References). 6.7 Hydrogen embrittlement relief heat treatment Steel parts with a maximum tensile strength greater than or equal to 1000 MPa and surface-hardened workpieces shall be heat treated to reduce hydrogen embrittlement. The heat treatment process and grade shall be in accordance with GB/T 19350 or as specified by the purchaser. When heat treatment for stress relief before electroplating or for hydrogen embrittlement relief after electroplating is specified (see 6.6), the time and temperature of the heat treatment process shall be marked in the mark, as shown in 5.4.Unless otherwise specified by the purchaser, the actual effect of the hydrogen embrittlement relief heat treatment shall be measured as follows. the threaded parts shall be subjected to residual hydrogen embrittlement test in accordance with GB/T 26107 or GB/T 3098.17; the relative dissolved hydrogen concentration in the steel shall be measured in accordance with ISO 15724. 7 Sampling The number of samples specified in GB/T 12609 shall be randomly selected from the inspection batch. The workpieces in the inspection sample shall be judged whether they meet the requirements of this document, and the inspection batches shall be divided into qualified batches or unqualified batches according to the sampling procedure of GB/T 12609.If other types of sampling inspection procedures are used, samples shall be randomly selected and the workpieces in the samples shall be inspected to determine whether they meet the requirements of this document. Appendix B (normative) Measurement of average coating thickness on small workpieces B.1 Materials WARNING. Perform platy stripping in a fume hood. Formaldehyde solution is toxic, flammable and has a pungent odor. Avoid inhalation of vapors and contact with skin and eyes. NOTE. Workpieces de-plated according to this appendix shall not be reused. Solution A and Solution B are suitable de-plating solutions. B.1.1 Solution A Dissolve 10 mL of formaldehyde (30% by mass fraction) in 500 mL of hydrochloric acid (1.16 g/mL< ρHCl< 1.19 g/mL), and then dilute with 500 mL of distilled or deionized water. B.1.2 Solution B 300 g/L ammonium nitrate (NH4NO3) solution. B.2 Steps For workpieces with a main surface area of less than 1 cm2, a sufficient number of workpieces shall be taken so that the mass of the coating is not less than 100 mg. Weigh the workpiece, accurate to milligrams, and then use a stripping solution to strip the zinc electroplated coatings at room temperature. If the workpiece has a complex shape, the inspection and rating surfaces shall be specified by the purchaser [see 4.2 b)]. Rinse the workpiece with running water, and if necessary, use a brush to remove loose sediment on the surface, dry it carefully and weigh it, and record the mass loss. Finally, calculate the thickness d of the zinc electroplated coating using the formula (B.1). where. ......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.