GB/T 5267.1-2002 Electroplating of fasteners

This part specifies the dimensional requirements and coating thickness of steel or steel alloy electroplated fasteners, and gives recommendations for eliminating hydrogen embrittlement for high tensile strength fasteners or hardened or case-hardened fasteners. This part applies to electroplated coatings on threaded fasteners, or other threaded parts. For the application of self-tapping screws, etc., see Chapter 8. The provisions of this part also apply to non-threaded parts, such as washers and pins. GB/T 5267.1-2002 Electroplated coatings on fasteners GB/T5267.1-2002 Standard download decompression password: www.bzxz.net

ICS21.060.01
National Standard of the People's Republic of China
GB/T5267.1-2002/IS04042:1999 replaces GB/T5267--1985
Fasteners
Electroplated coatings
Fasteners-Electroplated coatings(ISO4042.1999,IDT)
2002-12-05
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
Implementation on 2003-06-01
GB/T5267.1—2002/ISO4042:1999 This part is one of the national standard "Surface treatment of fasteners" series standards. This series includes: a) GB/T5267.1-2002 Fastener Electroplating; b) GB/T5267.2-2002 Fastener Non-electrolytic Zinc Flake Coating. This part is equivalent to the international standard ISO4042:1999 "Fastener Electroplating" (English version). This part replaces GB/T5267-1985 "Threaded Fastener Electroplating". Compared with GB/T5267--1985, the main changes of this part are as follows: - Modify the standard number (GB/T5267 for the 1985 edition and GB/T5267.1 for this edition); - Adjust the terms and definitions (Chapter 2 of the 1985 edition; Chapter 3 of this edition); - Cancel the conditions for use of electroplated layers (4.2 of the 1985 edition); - Add the provisions on the upper deviation value of the coating thickness for pitch P = 0.2 ~ 0.3mm, and adjust the provisions on the upper deviation value of the coating for some other pitches (Tables 4 and 5 of Chapter 5 of the 1985 edition; Table 2 of this edition); - Cancel the provisions on the acceptance inspection of coating thickness in the old standard and adopt the provisions of GB/T90.1 (Chapter 8 of the 1985 edition; Chapter 11 of this edition);
Adjust and supplement the information on removing hydrogen embrittlement (Chapter 9 and Appendix C of the 1985 edition, Chapter 6 of this edition Chapter and Appendix A); cancel the measurement method of local thickness (Appendix B of the 1985 edition); - add the code marking system for the thickness of the electroplated layer of threaded parts (see Chapter 13 and Appendix E), - adjust the provisions of the "Guidelines for the Acceptable Thickness of Metallic Coatings" (Appendix E of the 1985 edition; Appendix C of this edition); add examples of coating marking (see Appendix F). Appendices D and E of this part are normative appendices, and Appendix A, Appendix B, Appendix C, Appendix F and Appendix G are informative appendices. This part is proposed by the China Machinery Industry Federation. This part is under the jurisdiction of the National Technical Committee for Standardization of Fasteners (CSBTS/TC85). This part is drafted by the Mechanical Science Research Institute. This part was first published in July 1985.
1 Scope
Fasteners
Electroplating
GB/T52 67.1—2002/ISO4042:1999 This part specifies the dimensional requirements and coating thickness of steel or copper alloy electroplated fasteners, and gives recommendations for eliminating hydrogen embrittlement for high tensile strength fasteners or hardened or case-hardened fasteners. This part applies to electroplating of threaded fasteners, or other threaded parts. For applicability to self-tapping screws, etc., see Chapter 8. The provisions of this part also apply to non-threaded parts, such as washers and pins. 2
Normative referenced documents
The provisions in the following documents become the provisions of this part through reference in this part of GB/T 5267. All subsequent amendments (excluding errata) or revisions of dated referenced documents are not applicable to this part; however, parties to agreements based on this part are encouraged to investigate whether the latest versions of these documents can be used. For undated referenced documents, their The latest version applies to this part. 2 Fastener acceptance inspection (idtISO3269.2000) GB/T90.1-2002
GB/T192-1981 Basic tooth profile of common thread GB/T1237-2000
Fastener marking method (egvISO8991:1986) GB/T25161981
Ordinary thread deviation table (diameter 1~355mm) Fastener mechanical property inspection Hydrogen embrittlement preload test parallel bearing surface method (idtGB/T3098.17-2000
ISO15530:1999)
GB/T3934-1983
GB/T5782-2000
GB/T9145-—1988
GB/T 9797--1997
GB/T9798-1997
GB/T9799—1997
GB/T98001988
G B/T10125--1997
GB/T11374-1989bzxz.net
GB/T13346—1992
ISO9587)||tt| |1SO95882
3 Terms and definitions
General thread gauge (neq1SO1502:1978) Hexagon head bolt (eqvISO4014:1999) Medium precision general thread limit size of commercial fasteners (egvISO965-2:1980) Metal coating nickel + chromium and copper + nickel + chromium electrodeposition layer (egvISO1456:1988) Metal coating Covering nickel electrodeposited coating (eqvISO1458:1988) Metallic coating Zinc electroplated coating on steel (eqyISO2081:1986) Chromate conversion coating of electroplated zinc and electroplated zinc (eqvISO4520:1981) Artificial atmosphere corrosion test Salt spray test (eqvISO9227:1990) Non-destructive measurement of thickness of thermal spray coatings (neqISO2064:1980) Metallic coating Electroplated zinc coating on steel (idtISO2082:1986) Metallic and other inorganic coatings Pretreatment of steel products to reduce the risk of hydrogen embrittlement Metallic and other inorganic coatings Post-plating treatment of steel products to reduce the risk of hydrogen embrittlement The terms and definitions given in this part of ISO are used together with those given in GB/T11374 (especially effective surface, test area, local thickness and minimum local thickness) and GB/T90.1. 3.1
The number of fasteners of the same type and size in a manufacturing batch processed at the same time and by the same process. 1) To be issued.
2) To be issued.
GB/T5267.1—2002/ISO4042:19993.2
Production operation (management)
Batch of parts for which the coating process or composition is continuous without any change. 3.3
Batch average thickness
Assuming that the coating is evenly distributed on the surface of the batch of parts, calculate the average thickness of the coating. 3.4
Dry baking
The process of heating parts at a given temperature and for a specified time to minimize the risk of hydrogen embrittlement. 3.5
Dry baking time
The time the parts must be kept at the specified temperature. 4 Dimensional requirements and gauge inspection
4.1 Dimensional requirements before electroplating
Unless it is expressly specified that a thicker coating than the standard thread is allowed as far as possible for threads or other parts to meet functional requirements, the dimensions before electroplating shall comply with the provisions of the relevant national standards or other applicable standards. The coating thickness applies to ordinary threads specified in GB/T192, GB/T9145 and GB/T2516, and depends on the availability of basic deviations, and also on the thread and the following tolerance zone positions: external threads: multi, fe;
-internal threads: G, or when required: H.
These tolerance zone positions are preferred for electroplating. 4.2 Dimensional requirements after electroplating
After electroplating, ordinary threads shall be inspected in accordance with GB/T3934: use a go gauge with a tolerance zone position of h or H for external or internal threads respectively.
Other product dimensional requirements apply only before electroplating. Note: It should be noted that in the case of internal wrenching, relatively thick coatings may affect the dimensions with tighter tolerances. In this case, the supply and demand parties should reach an agreement. The applicability of the recommended coatings for ordinary threads is subject to the basic deviation and pitch of the relevant threads and the position of the tolerance zone. In the case of external threads, the coating should not exceed the zero line (basic dimension); in the case of internal threads, it should not be lower than the zero line. That is, if the tolerance zone fails to reach the zero line (basic dimension), only a moderate degree of coating friction can be electroplated for the internal thread with a tolerance zone position of H. 5 Other requirements
Other electroplating requirements involving appearance, adhesion, toughness and corrosion resistance shall comply with the relevant national standards (GB/T9797, GB/T9798:GB/T9799 and GB/T13346). 6 Measures to reduce hydrogen embrittlement
Parts are at risk of hydrogen embrittlement failure under the following conditions: high tensile strength or hardened or surface hardened; adsorbed hydrogen atoms,
- Under tensile stress.
When the core hardness or surface hardness is greater than 320HV, hydrogen embrittlement should be tested during the process, such as in accordance with GB/T3098.17, to ensure that the hydrogen embrittlement occurring during the process is under controllable conditions. If hydrogen embrittlement is found, the parameters of the manufacturing process should be modified, including the drying process (for more detailed information, see Appendix A). 2
GB/T5267.1-2002/ISO4042:1999 When the hardness exceeds 365HV, the supplier and buyer should clearly stipulate in the agreement how to control the risk of hydrogen embrittlement; if there is no such agreement, the manufacturer should adopt its recommended operating procedures to reduce the risk of hydrogen embrittlement. It cannot be guaranteed to completely eliminate hydrogen embrittlement. Any process modification should be evaluated if it is desired to reduce the probability of hydrogen embrittlement. Note: Process testing during production is an effective method to reduce hydrogen embrittlement. 7 Corrosion Protection Measures
The corrosion protection performance of the electroplated coating depends mainly on the coating thickness. In addition to increasing the coating thickness, chromate conversion treatment can also increase the corrosion protection of zinc and barrier coatings.
The duration and frequency of contact with metal products and raw materials, humidity and operating temperatures may affect the protective performance of the coating. When uncertainty arises, it is necessary to listen to expert advice. Since the anode of zinc (Zn) or cadmium (Cd) on iron is smaller than that of steel-based metal products, cathodic protection should be provided. In contrast, nickel (Ni) and chromium (Cr) plating require larger anodes than steel-based metal products, and when the coating is damaged or pitted, corrosion of the parts may be accelerated.
For details of zinc plating, please refer to GB/T13346;
For details of zinc plating, please refer to GB/T9799;
For details of nickel plating, please refer to GB/T9798;
For details of nickel + chromium and copper + nickel + chromium plating, please refer to GB/T9797; For details of chromate conversion treatment, please refer to GB/T9800
Note: The corrosion resistance salt spray test data of metal coatings are given in the informative Appendix B. 8 Applicability to fasteners that can be cut or rolled out with matching internal threads All recommended coatings are applicable to screws that can be cut or pressed out with matching internal threads, such as wood screws, self-tapping screws, self-drilling self-tapping screws and self-extrusion screws. Unless otherwise specified, the maximum value of the batch average thickness given in Table 1 can be ignored. 9 Technical requirements for coating thickness
The nominal coating thickness recommended by the relevant electroplating standards, as well as the corresponding local thickness and batch average thickness, are given in Table 1. In order to reduce the risk of interference in thread assembly caused by coating thickness, the coating thickness shall not exceed 1/4 of the basic deviation of the thread, see the values ​​specified in Table 2.
Note: The guidance value of the acceptable coating thickness is given in the informative annex C. The actual coating thickness shall be measured by one of the methods specified in Chapter 10, and the measured value shall comply with the provisions of Table 1. Table 1 Coating thickness
Effective coating thickness
Nominal coating thickness
Local thickness measurement see 10.1.
b Batch average thickness measurement see 10.2.
Local thickness
Batch average thickness
Unit is micron
If the nominal length of the threaded part is >5&, when measuring the batch average thickness, the nominal coating thickness less than that specified in Table 1 should be used, see Table 2.
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GB/T5267.1—2002/IS04042:199910 Measurement of coating thickness
10.1 Local thickness
The local thickness shall not be less than the minimum thickness specified in the order and shall be measured by one of the methods specified in the coating standard. The thickness of bolts, screws and nuts shall be measured on the test surface shown in Figure 1. - Measurement location.
Figure 1 Measurement location of local coating thickness of fasteners10.2 Batch average thickness
The batch average thickness measurement shall be carried out in accordance with the method described in Annex D of the specification. When the measured value exceeds the maximum batch average thickness, if the plated thread can be accepted by an appropriate go gauge (H or h), it shall not be rejected. 10.3 Consistency of test method
Unless otherwise specified, the local coating thickness shall be measured. Note: Most screws and bolts are rolled electroplated in batches, with the result that the maximum coating thickness is always at the end of the part. This results in an increase in the length or diameter of the bolt or screw, and it is acceptable to reduce the coating thickness according to the pitch size. 11 Sampling inspection of coating thickness
Sampling inspection of coating thickness shall be in accordance with GB/T90.1. 12 Plating Technical Requirements
When ordering electroplated threaded parts in accordance with the requirements of this standard, the following information shall be provided to the electroplater: coating designation and, if required, the desired coating in accordance with this standard; a
Part material and condition, such as heat treatment, hardness or other properties that may be affected by the electroplating process; stress relief condition, if required, before electroplating; if required, technical requirements for preventive measures against hydrogen embrittlement risk (see Clause 6); if required, batch average coating thickness measurement is preferred (see Clause 10); technical requirements for selective plating or thread size reduction; requirements for gloss or matte, unless otherwise specified, bright treatment shall be provided; additional coating technical requirements, such as lubrication requirements. 13 Marking
Fastener marking shall be in accordance with the relevant product standards. The marking of the surface coating shall be added to the product marking according to GB/T1237 and shall meet the following requirements:
Class A: See the code marking method in normative Appendix E, or Class B: See the classification and type codes specified in GB/T9797 (nickel + chromium and copper + nickel + chromium), GB/T9799 (zinc), GB/T13346 (cadmium) and GB/T9800 (chromate conversion film). See informative Appendix F for examples of coating marking.
A.1 Introduction
Appendix A
(Informative Appendix)
Measures to Remove Hydrogen Embrittlement
GB/T5267.1-2002/IS04042:1999 When hydrogen atoms enter steel or certain other metal products, such as aluminum or titanium alloys, it may cause loss of ductility or load-bearing capacity, cracks (usually submicroscopic) or severe brittle failure under stress conditions below the yield strength or at the nominal strength of the alloy. This phenomenon often occurs in alloys and is manifested as: when checked by conventional tensile tests, although there is no significant reduction in ductility, it is usually considered to be delayed brittle failure, hydrogen stress cracking or hydrogen embrittlement due to hydrogen. Hydrogen atoms may enter the matrix during heat treatment, gas carburizing, cleaning, packaging, phosphating, electroplating, autocatalysis, and in service environments due to the reaction of cathodic protection or corrosion. Hydrogen atoms may also enter during processing, such as thread rolling, charring due to improper lubrication during machining and drilling, and welding or brazing operations. Parts that have been machined, ground, cold formed or cold drawn, especially after tumbling heat treatment, are extremely susceptible to hydrogen embrittlement. Research results show that any material susceptible to hydrogen embrittlement can directly show the density of its trapped hydrogen in a given test (type and effectiveness of sampling). Therefore, the relationship between time-temperature and drying process depends on the composition and structure of the steel, as well as the coating metal material and the electroplating process. In addition, for the highest strength steels, the effectiveness of the drying process decreases rapidly with decreasing time and temperature. Note 1: The above two paragraphs are an introduction to the basic content of ISO9588. Note 2: "Sampling" refers to certain metallographic features in the steel structure, and also includes external atoms, lattice displacements, etc. to which hydrogen atoms may be bound. The hydrogen so bound is very (no longer) free to move to high stress areas and promotes the initiation of catalytic failure. Sampling may be reversible or irreversible. For more information, see Professor Troiano's paper Troiano, A.R, The role of hydrogen and other interstitials in the mechanical behavior of metals, Transactions of the American Society of Metals, Vol. 52, 1960, p. 54.] There are many other causes of hydrogen embrittlement in fasteners. The entire manufacturing process should be controlled to reduce the probability of hydrogen embrittlement to a minimum. The procedure examples given in this appendix can reduce the probability of hydrogen embrittlement during the electroplating process of fasteners. A.2 Measures to reduce stress
Fasteners with cold working hardness greater than or equal to 320 HV and electroplated can add a stress relief process. However, this process should be carried out before the cleaning process specified in A.3. If the process is carried out in accordance with the requirements provided in Chapter 12, the temperature and duration of the process should vary according to the design, process and heat treatment conditions of the parts, and the electroplater should be notified in a timely manner. The heat treatment of parts with a hardness exceeding 320 HV after machining, grinding, cold forming or cold drawing should comply with ISO9587. In cases where residual stresses are intentionally introduced, stress relief will not be satisfactory, such as thread rolling of screws after heat treatment. A.3 Cleaning process
The cleaning process may cause hydrogen to adhere to the steel and cause brittle fracture after electroplating. Unless otherwise agreed, parts with a hardness greater than or equal to 320 HV after heat treatment or work hardening shall be cleaned using an anti-corrosive acid, alkaline or mechanical method. The time of immersion in the anti-corrosive acid depends on the state of the part surface that can be tolerated and the minimum duration. NOTE: The addition of a suitable anti-corrosive acid can reduce the attack on the steel and the hydrogen adhesion. Parts with a hardness greater than 385 HV after heat treatment or cold work hardening or property level 12.9 and above are not suitable for pickling. It is reasonable to use special acid-free methods for pre-treatment, such as dry grinding, sandblasting or alkaline rust removal. For electroplating, the surface of steel parts should be specially prepared, that is, cleaned with a minimum immersion time before electroplating. A.4 Electroplating process
For fasteners with a hardness greater than 365 HV after heat treatment or cold work hardening, it is reasonable to use a high cathode power electroplating solution. GB/T5267.1—2002/IS04042：1999A.5 Drying process
With the increase of hardness, the increase of cold work hardening degree and the increase of carbon content and (or) certain other elements in steel parts, the solubility of hydrogen and the total amount of absorbed hydrogen generated during pickling and electroplating will also increase. At the same time, the limit amount of hydrogen that can cause brittle fracture is reduced. The beneficial effect of the baking process after electroplating is that hydrogen atoms are released due to the evaporation and (or) irreversible collection of hydrogen in steel. The parts should be dried for 4h, and it is best to do it 1h after electroplating and before chromate treatment. The temperature of the parts is 200℃～230℃. The maximum temperature should take into account the type of coating material and base material. For some materials, such as tin and the physical properties of some parts, the use of these temperatures may produce opposite results. In this case, a lower temperature and a longer tempering holding time should be required. These requirements should be agreed upon by both the supplier and the buyer.
Increasing the coating thickness increases the difficulty of hydrogen release. When the coating thickness is only 2μm to 5um, the risk of hydrogen embrittlement can be reduced by promoting the use of a transitional drying procedure.
To reduce hydrogen embrittlement, users may agree to use other methods that can be shown to be effective. It should not be assumed that the recommended drying procedure can completely avoid hydrogen embrittlement in all cases. If the drying time and temperature for a part have been proven to be effective, the time and temperature can be used as an alternative. However, for all parts, the temperature exceeding the tempering temperature of the part should not be used for drying. Generally, lower drying temperatures require longer holding times. The combination of the chemical composition and process conditions of some steels may produce a higher sensitivity to hydrogen embrittlement. Fasteners with larger diameters are less sensitive than those with smaller diameters. At the time of publication of this part, it has not been considered to give as accurate a drying duration as possible. 8h is a typical example of a drying duration considered. However, at a temperature of 200℃~230℃, depending on the type and specification of parts, part geometry, mechanical properties, cleaning and electroplating process, it is possible to select a drying duration in the range of 2h~24h, which is suitable for use. Appendix B
(Informative Appendix)
GB/T5267.1-2002/IS04042:1999 Salt spray corrosion protection of metal coatings
This appendix gives the salt spray corrosion protection performance of zinc and cadmium coatings after chromate conversion (see Tables B.1 and B.2), and nickel and nickel/chromium coatings (see Table B.3) under the salt spray test conditions specified in GB/T10125. Table B.1 Protection performance of zinc and cadmium against neutral salt spray corrosion Coating marking code:
(Class B)
Fe/Zn or Fe/Cd3c1A
Fe/Zn or Fe/Cd3c1B
Fe/Zn or Fe/Cd3c2C
Fe/Zn or Fe/Cd3c2D
Fe/Zn or Fe/Cd5c1A
Fe/Zn or Fe/Cd5c1B
Fe/Zn or Fe/Cd5c2C
Fe/Zn or Fe/Cd5c2D
Fe/Zn or Fe/Cd5Bk
Fe/Zn or Fe/Cd8c1A
Fe/Zn or Fe /Cd8clB
Fe/Zn or Fe/Cd8c2C
Fe/Zn or Fe/Cd8c2D
Fe/Zn or Fe/Cd8Bk
Fe/Zn or Fe/Cd1 2c1A
Fe/Zn or Fe/Cd12c1B
Fe/Zn or Fe/Cd12c2C
Fe/Zn or Fe/Cd12c2D
Fe/Zn or Fe/C d12Bk
Fe/Zn or Fe/Cd25clA
Fe/Zn or Fe/Cd25c1B
Fe/Zn or Fe/Cd25c2C
Fe/Zn or Fe/ Cd25c2D
Fe/Zn or Fe/Cd25Bk
Nominal coating thickness/μm
Chromate treatment mark
Time for first appearance of white
Time for first appearance of red
Time for rust/h
Boiler coating
No suitable data yet
aFor the type code of zinc coating, see GB/T9799: for the type code of coating, see GB/T13346. bFor the code marking method, see Chapter 13.
. For the mark of chromate treatment, see Table B2. dThin coatings weaken the performance of chromate treatment. Zinc coating
GB/T5267.1—2002/ISO4042:1999 Classification
Type code
Opaque
Table B.2 Chromate treatment marking
Typical appearance
Transparent, bright, sometimes with slight blue Slightly iridescent and transparent
Yellow iridescent
Olive green faintly visible Brown or bronze
Slightly iridescent black
Note: This table supplements the black treatment compared to GB/T9800. aIn addition to A~D, black film layer can also be selected. Protection
Mild, e.g., protection against rust when handled or against high humidity under moderately corrosive conditions
Quite good, including protection against some organic gases and nitrogenVarious degrees of corrosion protection
Table B.3 Salt spray corrosion protection of nickel and nickel/chromium coatingsKey layer marking* (Class B)
Copper or copper alloy substrate
Nickel + chromiumd
Cu/Ni3b
Cu/Ni5b
Cu/Ni10bCu/Ni10bCrr
Cu/Ni20b
Not recommended
Cu/Ni20b Cr
Cu/Ni30d
Fe/Ni5b
Fe/Ni10b
Fe/Ni20b
Fe/Ni30b
Not recommended
a For the type code of nickel plating, see GB/T9797. b For the code marking method, see Chapter 13.
℃“b\ indicates bright nickel plating, while \d\ indicates double-layer nickel plating. d“” indicates ordinary chrome plating, with a minimum thickness of 0.3μm. Iron metal material matrix
Nickel + chromium or copper +
Nickel + chromiumd
Fe/Ni 5bCr
Fe/Ni10bCr
Fe/Cu10Ni5b
Fe/Ni20bCr
Fe/Cu20Ni
eFor Ni/Cr coating, neutral salt spray test (NSS) is usually not required, 40dCr
fFor thinner coating, in copper accelerated salt spray test (CASS), it is meaningless because the implementation time is too short. 10
The first appearance of red rust on the effective surface
Neutral salt spray test
(NSS)e
Copper accelerated salt spray
Test (CASS)
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