Detail of GB/T 41950-2022

Introduction of GB/T 41950-2022

Foreword This document is drafted in accordance with the provisions of GB/T 1.12020 "Quasi-chemical guidelines for the first sub-rule". This document is modified to adopt ISO195982016 "metal cladding iron and alloy electric layer without hexavalent treatment" This document has made the following structural adjustments compared with ISO 19598-2016. A process in the order of "rolling lock and padlock" and "post-plating treatment" order The technical differences between this document and ISO 19598-2016 and the reasons for them are as follows: the definitions of "white rust" and "red rust" (see 3.13.2) have been added to define the type; one of the definitions of "ZnNi " definition of nickel mass fraction from "12% to 16%" to "8% to 16%" (see Table 1, Table 1 of ISO195982016), in order to meet my practical applications Changed the requirements of the six-valent test (see 83 in line with my actual application of the document made the following editorial changes 4.3 "back" to "layer table" - a knowledge of the example of "//" to "/" (see 4.58.1) Changed the title of 7.1 from "Surface front and electrical" to "Control and process flow" Added reference to Figure 1, Table 3 and Table 6. Changed the informative references in the thickness and bond tests. Please note that some of the contents of this document may be patent related. The issuer of this document does not assume responsibility for identifying patents. This document is presented by the China Machinery Industry Federation. This document is attributed to the National Technical Committee for Standardization of Metal and Non-metal Coverings (SAC/TC 57). Introduction The hexavalent chromium-free system differs from the hexavalent chromium system in two main ways. The Cr(VI)-free system has no self-healing capability. The hexavalent chromium-free system has higher heat resistance (>150C while the heat resistance limit of the hexavalent system is no more than 0C6). 1 Range This document specifies the identification of zinc and zinc alloy plating systems without hexavalent chromium passivation on steel surfaces and the minimum layer of resistance required to be achieved under the specified test conditions, with or alloy in the alloy electric called alloy plating or zinc-iron alloy plating. This document applies to the steel surface without hexavalent chromium clocking treatment of zinc and zinc alloy electric lock layer. The main purpose of the electroplating layer or lock layer system is to protect steel parts from corrosion. 2 normative reference documents The content of the following documents through the normative references in the text and constitute the essential provisions of this document. Among them, note the date of the reference document, only the date of the corresponding version applicable to this document; do not note the date of the reference document and its latest version (including all the change orders) applicable to this document. ISO 2080 Terminology for surface treatment of metals and other inorganic coatings Note GB/T 3138-2015 Terminology for surface treatment of metal and other inorganic coverings (ISO 208-2008, IDT) ISO 3497 metal cladding layer thickness measurement X-ray spectrometry Note GB/T 16921-2005X-ray spectrometry for thickness measurement of metal cladding overlays(ISO 3497:2000,IDT) ISO 3613:2021 acid conversion film test method for metals and other inorganic coverings of gold and alloys ISO 9227 artificial atmosphere corrosion test salt spray test Note:GB/T 10125-2021 artificial atmosphere corrosion test salt spray test (ISO 9227:2017,MOD) ISO 9587 metal and other inorganic coverings to reduce the risk of brittle steel pretreatment Note GB/T 19349-2012 Pretreatment of metals and other inorganic coverings for the reduction of brittle hazards of steel ISO 9587:2007,IDT) ISO 9588 Treatment of steel after coating with metal and other inorganic coverings to reduce the risk of brittleness 3 Terms and definitions The terms defined in ISO 2080 and the following terms and definitions apply to this document 4 Marking 4.1 Plating layer The electroplated layer shall consist of zinc or zinc alloy, the identification of which is shown in Table 1 4.2 Plating Passivation treats the lock layer with a solution free of hexavalent chromium to produce a chemical transformation film to improve the corrosion resistance of the coating. The conversion film is available in different color options. Passivation without hexavalent chromium is a new coating system and its chemical identification is shown in Table 2 4.3 Closure layer or surface coating film The sealer or surface coating improves corrosion resistance and is identified in Table 3 Closed layer consists of organic and / or inorganic compounds without hexavalent chromium, the thickness usually reaches 2m with room temperature cleaning agent to remove the coating (such as oil film, grease or wax film), this document is not considered a closed layer. The surface coating layer is a thin organic coating free of hexavalent chromium, which may require high temperature curing and is usually thicker than 2m. The surface coating layer is specially applied to improve the corrosion resistance of the black passivation layer and to make the color darker. The impact of the sealer or surface coating on the performance of the parts, such as contact resistance, weldability, fuel compatibility, adhesion properties, etc., should be evaluated on a case-by-case basis when using this document. 5 Information to be provided to the plater The information to be provided to the plater should include at least the following Tensile strength of the component (with due consideration to the requirements of 7.4)a bInformation on the component (base material production method heat treatment) The main surface information required in 4.4;c d layer used (4.5) If there is a need for more requirements, such as appearance, friction properties and dielectric resistance, can be added accordingly to the performance of the coating used and the corresponding test. 6 Substrate material Plating in accordance with this document, currently the most widely used in low-alloy steel. For other iron-based materials, such as cast iron or powder metallurgy, materials containing a large number of passivated alloying elements or materials with special strength properties, special adjustments can be made to the treatment process (pretreatment, plating, post-plating treatment) when necessary, and additional measures may be taken to meet the requirements of this document. Therefore, the electric party should have detailed information on the composition, characteristics and production process of the parts. If the tensile strength of the steel parts to be plated is 1000 N/mm and above in the period order (such as the choice of material hardening process and assembly procedures), very reliable measures should be taken to eliminate the possibility of damage caused by internal brittleness. The parts to be plated should not have any material defects, processing defects or surface defects that could adversely or unpredictably affect the corrosion protection and/or appearance of the locking layer. Through the standard cleaning and pretreatment process, all impurities (such as corrosion products or chemical skin, oil, grease, dirt, etc.) should be removed from the surface of the parts, and there should be no residues. Agreement can be reached on surface quality issues if necessary 7 Plating treatment 7.1 Process control and process flow To ensure process reliability and repeatability, the entire pre-treatment and plating process, the physical data associated with it (e.g. treatment time and temperature) and the chemicals used should be recorded and maintained, and optimized as necessary. The frequency of monitoring of over-control limits and analysis procedures for each process shall be specified. Measures to meet these requirements should be described and documented by the electroplating party. 7.2 Barrel plating and rack plating 7.2.1 Barrel plating Parts that are normally plated by the barrel process are mainly screws, nuts and other small parts. After the parts are bulk loaded into the barrel, the barrel is kept rotating during the pretreatment and plating process. The barrel rotation ensures that the layer of all parts in the barrel is essentially uniform, which can also lead to surface damage. Damage can be mitigated by, for example, reducing the speed of the barrel and reducing the height of the drop for loading and unloading the plated parts. In general, the corrosion resistance of barrel plated parts is not as good as padlocked parts. 7.2.2 Padlocking Parts due to the size, shape or should meet the special requirements, can be used to hang plating process. In the padlock process, the parts are clamped on the pendant for electric lock. The plating characteristics (especially the thickness of the plating) can vary depending on the location of the part on the pendant, but this can be optimized, for example, by designing special pendants for specific parts. 8 Plating and test method requirements 8.1 Thickness The thickness of the dm zinc and zinc alloy plating on the gold side of Table 5 Table 6 should be measured using the optical spectrometer in ISO 3497. Can use other methods examples are as follows. a) GB/T6462 in the microscope method GB/T4955 in the library method b c)Magnetic method in GB/T4956. d)Eddy current method in GB/T4957 and GB/T30565 Do not consider the thickness of the passivation layer and the closure layer. 8.2 Bonding force The test workpiece in the (22010)C conditions of holding 30min, and then into the 15C25C water cooled, the layer should be no flaking or blistering (see GB/T5270 in the thermal test) If feasible, it is appropriate to use the bending test or friction polishing test as a further bonding test No hexavalent chromium 8.3 According to ISO3613:2021 in 6.5.3 of the precipitation layer should be free of hexavalent chromium 8.4 Accelerated corrosion test 8.4.1 Overview The process stability of the plating can be controlled in accordance with the salt spray test in ISO 9227. For the identification of electrical components the guidelines in ISO/TR16335 for example can be used. Note: Since (actual conditions) temperature, humidity, gas conditions, etc. are different from the test gas limited in the plus test, so, without verification, the results of the accelerated corrosion test can not be used to predict the corrosion behavior of the parts in the actual service environment. 8.4.2 Minimum corrosion resistance of zinc and zinc alloy plating after passivation In the given plating system and test the minimum test time, there should be no corrosion products, such as plating white rust or base red rust. Corrosion assessment should be based on the main surface of the component. The minimum corrosion resistance applies to the post-lock state, also applies to the test after the first 120C holding 24 heat aging test. And for Zn/An/TO plating system, the thermal aging test is not required. 9 Test report 9.1 General information The plating party shall provide a test report, which gives the following information. b Proof of consistency with the requirements of this document. The name of the electroplating party. d) detailed records of the worker (roll and system) 9.2 tensile strength greater than or equal to 1000N/mm' material on the plating Test report should prove that the prescribed steps have been taken to minimize the risk of hydrogen embrittlement 9.3 Test results The tests in 8.2, 8.3 and 84 should be synchronized with production The test report should include the following details. a) Test results as specified in 8. b) Information on the testing party (supplier and/or subcontractor and/or independent testing laboratory) Bibliography

Contents of GB/T 41950-2022

Foreword Introduction 1 Range 2 normative reference documents 3 Terms and definitions 4 Marking 5 Information to be provided to the plater 6 Substrate material 7 Plating treatment 8 Plating and test method requirements 9 Test report Bibliography