Metallic coatings－Electroplated coatings of cadmium on iron and steel
Some standard content:
National Standard of the People's Republic of China
Metallic coatings
Electroplated coatings on iron and steel
Melallic coatings-Electroplated coatings of cadmlum on iron and steel GB/T13346-92
This standard is equivalent to the international standard 1502082-1986 "Metallic coatings-Electroplated coatings on iron and steel". 1. Subject content and applicable scope
This standard specifies the technical requirements and test methods for electroplated coatings on iron and steel. This standard is applicable to cadmium electroplated coatings that prevent brain corrosion of steel under various conditions of use. This standard does not apply to:
Cadmium electroplated coatings on unformed plates, strips or wires: h. Coatings on objects that may come into contact with food or beverages (the toxicity of cadmium can cause serious harm to the human body). 2 Reference standards GB 12383 Metal coatings and chemical treatment methods GB4955 Metal coating thickness measurement Coulometric method by anodic dissolution GB4956 GB 5270 GB 6458 GB 6462 GHB 6463 GB 9800 GB 12609 Measurement of thickness of non-magnetic coatings on magnetic metal substrates Magnetic method Test method for adhesion strength of metal coatings (electrodeposited and chemically deposited coatings) on metal substrates Non-susceptible salt spray test (NSS) for metal coatings (Test) Thickness of metal and oxide coatings in cross section Microscope measurement of thickness of metal and other inorganic coatings Review of methods for measuring thickness of chromate conversion coatings of electroplated zinc and electroplated cadmium Electrodeposited metal coatings and related finishing counting sampling inspection procedures GB/T12611
Technical requirements for quality control of metal parts before plating 3 Terminology
3.1 Main surface
Certain surfaces on the parts that have been or are to be covered, on which the covering layer is important to the appearance and (or performance of the parts). 3.2 Local thickness
The arithmetic mean of the specified number of thickness measurements within the basic measuring surface Mean. 3.3 Minimum local thickness
The minimum local thickness measured on the main surface of a single workpiece. 4 Base metal
The quality of the base metal of the parts before plating should meet the requirements of GBT12611, otherwise, the supply and demand parties shall agree separately. Approved by the State Administration of Technical Supervision on 19920107
Implementation on 1992-10-01
Information that the purchaser should provide to the supplier
The purchaser should provide the following information to the supplier:
This standard number (GB/T13346)
Requirements for coating thickness,
GB/T 13346
The main surface shall be indicated by drawings or appropriate markings; c
The properties, surface state and processing accuracy of the base metal; the surface appearance requirements of the coating;
The requirements for heat treatment before and after plating:
The type of chromate or other conversion coating. It should be noted that the chromate conversion coating can be omitted or an alternative conversion coating can be applied only when the purchaser specifically requests it:
Sampling or inspection requirements;
Any special requirements and restrictions for pre-plating preparation and electroplating process; Packaging and storage of electroplated parts or transportation requirements. 6 Coating representation method
The representation method of the electroplated coating shall comply with the provisions of GB1238. 7 Coating thickness series
7.1 Service life
The coating has excellent corrosion resistance under marine atmosphere conditions. The thickness of the cadmium coating should be selected depending on the severity of the use environment and (or) the length of the service life. Fe/Cd5C (see 7.2) is generally only used in dry indoor environments. If the use environment is relatively harsh and (or) the service life is long, a thicker coating should be used. 7.2 Correspondence between coating and use environment and service life Table 1 lists the thickness series of cadmium electroplating, the minimum local thickness of the coating after chromate treatment, and their correspondence with the use environment and service life. When there is a chromate conversion film, it is followed by the symbols specified in GB9800. The specific description of other conversion films should be given separately.
Table 1 Thickness series, minimum local thickness, use environment and service life of cadmium coating on iron Use conditions or service life
With the increase of the severity of the use conditions or service life, the minimum local thickness increases accordingly
Thickness series
Fe/Cd 5 c
Fe/Cd 8 c
Fe/Cd 12 c
Fe/Cd 25 e
Minimum local thickness, μm
Note, the manganese coating of the thickness series Fe/Cd12c and Fe/Cd25r should have a colored 2-level chromate conversion film (see GB9800). 7.3 Thickness series
Composition of thickness series:
Chemical symbol Fe, representing the base metal (steel or iron), followed by a slash! a.
Chemical symbol Cd, indicates the coating:
Number, indicates the minimum local thickness of the coating, in μm: d. The application symbol indicates the presence of chromate conversion coating, and the type and code of the conversion coating should be indicated when necessary. For detailed provisions on the method of indicating conversion coating, see GB9800.
GB/T 13346-92
Fe/Cd 8c2A
This coating series indicates that the electroplating layer is at least 8um on the steel substrate: In addition: Chromate conversion coating,
2-Chromate conversion coating grade. Grade 2:
A\-Type of chromate conversion coating, light type. 8 Heat treatment
8.1 Overview
Some base metals should be heat treated as specified in 8.3 and 8.4 to reduce the risk of hydrogen embrittlement damage. In all cases, the heat treatment time should be calculated from the moment when each component fully reaches the specified temperature. Steel workpieces with a maximum tensile strength of 1050MPa (corresponding to a hardness of about 34HRC, 340HV or 325HR) and surface-rate workpieces exposed to heat treatment are required. Cathodic treatment in liquid or acid should be avoided before plating. Note: ① It is recommended to select a low hydrogen embrittlement chain pot process for steel workpieces with a tensile strength greater than 1450MPa (corresponding to a hardness close to 45HRC, 440HV or 415HR).
Figure: When the maximum tensile strength of the electroplated steel workpiece is greater than 1050MPa (corresponding to a hardness close to 340HV), it is not recommended to use a light filler in the electrosensitive wave.
8.2 Classification of steels
8.2.1 Except for surface hardened parts (see 8.3.2 and 8.4.2), the heat treatment conditions shall be selected according to the maximum tensile strength of the matrix. Steels may be classified according to their maximum tensile strength values (see Table 2). If only the minimum tensile strength value of a steel is given, the corresponding maximum tensile strength value of the steel may be determined according to Table 2.
Table 2 Correspondence between classification of steels, minimum tensile strength values and maximum tensile strength values Minimum tensile strength, MPa
>1 000~1 400
-1 400 -1 750
Corresponding maximum tensile strength, MPa
>1 050~1 450
>1 450~1 800
8.2.2 If the maximum and minimum tensile strength values of the steel are not indicated, the Vickers hardness values of 310410 and 560HV can be used, which are equivalent to the maximum tensile strengths of 1050 and 1450.1800MP8 respectively, and then the heat treatment conditions can be selected according to these strength values. 8.3 Stress relief before electroplating
8.3.1 If the purchaser requires the workpiece to be stress-relieved before electroplating (except for surface quenched workpieces), it is recommended to use the conditions listed in Table 3 for heat treatment. Other effective heat treatment conditions that appropriately increase the temperature and shorten the time can also be used for heat treatment. Table 3 Stress relief heat treatment before electroplating (except for surface quenched workpieces) Maximum tensile strength, MPa
2-1 050--1 450
21450~1800
>1 800
Temperature, c
Not required
190~220
190~220
190~220
Time, h
8.3.2 Heat treatment of surface-hardened workpieces should be performed at 130~150℃ for 5h. If the surface hardness of the base metal is allowed to decrease, a higher temperature and shorter time heat treatment condition can also be used. 8.3.3 If stress is eliminated after shot peening or other cold working treatment, the temperature should not exceed 220℃. 8.4 Elimination of hydrogen embrittlement after electroplating
8.4.1 Heat treatment to eliminate hydrogen embrittlement. Except for surface annealed plated parts, this should be carried out as soon as possible within 4 hours after the workpiece is annealed according to the conditions given in 4.
8.4.2 Surface annealed workpieces shall be heat treated in a humidity environment of 190~220℃ for not less than 2 hours, otherwise, it shall be carried out in accordance with 8.4.1. 8.4.3 If other temperatures and times have been proven to be effective for a certain workpiece and are acceptable to the manufacturer, they may also be used. However, the workpiece should not be heat treated above the tempering temperature.
Table 4 Heat treatment conditions for eliminating hydrogen embrittlement after electroplating (excluding surface quenched workpieces) Maximum tensile strength, MPa
21 050~1 450
>1 450~1 800
>1 800
9 Sampling
Temperature,
Not required
190~220
190220
190~220
Time,b
In order to check whether the coating meets the requirements of Chapter 10 of this standard, sampling should be carried out in accordance with the relevant provisions of GB12609. 10 Requirements for coating
10.1 Appearance
On the main surface, the electroplated parts should have no obvious visible coating defects, such as blistering, pitting, roughness, cracks or unplated areas. The position of the fixture contact marks that cannot be avoided on the workpiece should be agreed upon by the supplier and the purchaser. The plated parts should be clean and free of defects. If necessary, a sample should be provided or approved by the purchaser to illustrate the requirements for surface roughness.
Note: Heat treatment may cause a slight darkening of the appearance of the coating. 10.2 Radiation-plated thickness
10.2.1 Minimum local thickness
On the part of the main surface that can be contacted by a ball with a diameter of 20 mm, the cadmium coating should reach the minimum local thickness specified in the thickness series (see Table 1>). The purchaser may also specify another thickness. If the purchaser requires, other parts of the main surface should also reach the minimum local thickness value. 10.2.2 Thickness of the coating on small workpieces
In the case where the main surface of the workpiece is less than 100 mm, the minimum local thickness should be regarded as the minimum value of the average thickness measured by the method specified in 11.1.2.
10.3 Bonding strength
The coating should be well bonded to the substrate, and the bonding test The test is carried out by one or more methods suitable for cadmium coatings specified in GB5270. There should be no separation between the coating and the substrate after the test. 10.4 Application of conversion film
Conversion film, especially chromate conversion film, can improve the corrosion resistance of the coating. Only at the special request of the purchaser can the chromate conversion film be removed or replaced by other conversion films. Various types of chromate conversion films formed by radium coating are specified and explained in detail in GB9800. 10.5 Corrosion resistance of cadmium coating
The corrosion resistance of cadmium coating treated with chromate should meet the corresponding provisions in GB980. If the purchaser stipulates that the coating must be subjected to corrosion resistance test, the cadmium-plated parts shall be tested in accordance with the provisions of GR6458. The corrosion resistance requirements of cadmium coating shall be agreed upon by the supplier and the purchaser. 11 Test method
11.1 Thickness determination
11.1.1 Local thickness determination
GB/T 13346—92
The methods specified in GB6462, GB4955 and GB4956 are applicable to the thickness measurement of coatings on steel. In addition, other thickness measurement methods suitable for coatings in GB6463 may also be used. When there is a dispute over the thickness measurement, the method specified in GB4955 shall be used, except for workpieces with an upper surface less than 100 mm (see the method specified in 11.1.2).
Note: (When the key layer is rough, the results measured by the microscopic method and the wheel smearing instrument method may have large errors, and the results measured by the cross-sectional method may be larger than the thickness value measured on the optical coating.
② Before measuring the thickness using the method specified in GB4955, a soft release material (such as lead oxide grinding paste) must be used to remove the chrome salt or other conversion film. Therefore, for thick conversion films, the measurement results will be slightly lower. 11.1.2 Determination of average thickness on small plated parts 11. 1. 2. 1 Measuring method
When the area of the main surface of the plated part is less than 100mm2, the thickness of the base layer shall be measured as follows: Take a sufficient number of parts so that the mass of the coating is not less than 100mm2. If the plated part has a complex shape, the area shall be agreed upon by both parties. The plated part shall be weighed accurately to 0.0001 mm2 and the coating shall be stripped at room temperature using a solution specified in 11.1.2.2. Wash the workpiece in running water and, if necessary, brush off the loose dark deposits on the surface (antimony deposits when using solution b or c), dry carefully and weigh, and determine the mass lost. The thickness of the cadmium coating is calculated by the following formula, in units of m. d=m×10mbzxZ.net
Where: m is the mass lost, mg
A is the area of the test surface, mm
β is the density of the cadmium coating, generally 8.6/cml11.1.2.2 Applicable stripping solution
solution g, ammonium nitrate (NH4NO3) 300g/Lsolution b: antimony trioxide (Sb2O3) 20g hydrochloric acid (p1.16/mL) 800 mL
water 200 mL
free liquid antimony trinitride (SbCls) 32g
hydrochloric acid (p≥l.16 g/mL) 800 mL
find 200 ml.
Dissolve blue-supported antimony or antimony nitride in hydrochloric acid, and then dilute with water. When the bond layer is completely removed in solution b or, that is, when the violent chemical reaction stops, the workpiece should be taken out of the solution immediately. If the workpiece is left in the solution for too long after the removal reaction is over, the base metal may be corroded. Note: Antimony trioxide and antimony trifluoride in salt are toxic and should not come into contact with the skin. ② When using solution b or, very toxic antimony trihydride gas will be released. It should be strictly prevented from being inhaled and operated in a fume hood. Additional notes:
This standard is proposed and managed by the National Technical Committee for Standardization of Metal and Non-metal Coverings. This standard was drafted by the 621st Institute and the 53rd Factory of the Ministry of Aeronautics and Astronautics. The main drafter of this standard is Sui Yongmo.4 Application of conversion film
Conversion film, especially chromate conversion film, can improve the corrosion resistance of the coating. Only under the special request of the purchaser can the chromate conversion film be removed or replaced by other conversion films. Various types of chromate conversion films formed by radium plating are specified and explained in detail in GB9800. 10.5 Corrosion resistance of cadmium coating
The corrosion resistance of cadmium coating treated with chromate should meet the corresponding provisions in GB980. If the purchaser stipulates that the coating must be subjected to corrosion resistance test, the cadmium-plated parts shall be tested in accordance with the provisions of GR6458. The corrosion resistance requirements of cadmium coating shall be agreed upon by the supply and demand parties. 11 Test methods
11.1 Thickness determination
11.1.1 Local thickness determination
GB/T 13346-92
The methods specified in GB6462, GB4955 and GB4956 are applicable to the thickness determination of coatings on steel. In addition, other thickness measurement methods suitable for coatings in GB6463 may also be used. When there is a dispute over the thickness measurement, the method specified in GB4955 shall be used, except for workpieces with an upper surface less than 100 mm (see the method specified in 11.1.2).
Note: (When the key layer is rough, the results measured by the microscopic method and the wheel smearing instrument method may have large errors, and the results measured by the cross-sectional method may be larger than the thickness value measured on the optical coating.
② Before measuring the thickness using the method specified in GB4955, a soft release material (such as lead oxide grinding paste) must be used to remove the chrome salt or other conversion film. Therefore, for thick conversion films, the measurement results will be slightly lower. 11.1.2 Determination of average thickness on small plated parts 11.1.2.1 Measuring method
When the area of the main surface of the plated part is less than 100mm2, measure the thickness of the base layer as follows: Take a sufficient number of parts so that the mass of the coating is not less than 100m. If the shape of the plated part is complex, the area should be agreed upon and approved by both parties. The plated part is weighed accurately to 0.0001 mm, and the coating is stripped at room temperature using a solution specified in 11.1.2.2. Wash the workpiece in running water and, if necessary, brush off the loose dark deposits on the surface (antimony deposits when using solution b or c). After careful drying, weigh and determine the lost mass. The thickness of the cadmium coating is calculated by the following formula, in units of m. d=m×10m
Where: m is the lost mass, mg
A——Area of the test surface, mm
β——Density of the cadmium coating, generally taken as 8.6 /cml11.1.2.2 Applicable stripping solution
Solution g, ammonium nitrate (NH4NO4) 300g/LSolution b: antimony trioxide (Sb2O3) 20g hydrochloric acid (p1.16/mL) 800 mL
water 200 mL
free liquid antimony trinitride (SbCls) 32g
hydrochloric acid (p≥l.16 g/mL) 800 mL
find 200 ml.
Dissolve the antimony dihydride or antimony dinitride in hydrochloric acid, and then dilute with water. When the bond layer is completely removed in solution b or, that is, when the violent chemical reaction stops, the workpiece should be removed from the solution immediately. After the removal reaction is over, if the workpiece is left in the solution for too long, the base metal may be corroded. Note: There is antimony trioxide and antimony trifluoride in the salt solution, so do not contact with the skin. ② When using solution b or, very toxic antimony trihydride gas will be released, which should be strictly prevented from being inhaled into the body and operated in a fume hood. Additional notes:
This standard is proposed and managed by the National Technical Committee for Standardization of Metal and Non-metallic Coatings. This standard was drafted by the 621st Institute and the 53rd Factory of the Ministry of Aeronautics and Astronautics. The main drafter of this standard is Sui Yongmo.4 Application of conversion film
Conversion film, especially chromate conversion film, can improve the corrosion resistance of the coating. Only under the special request of the purchaser can the chromate conversion film be removed or replaced by other conversion films. Various types of chromate conversion films formed by radium plating are specified and explained in detail in GB9800. 10.5 Corrosion resistance of cadmium coating
The corrosion resistance of cadmium coating treated with chromate should meet the corresponding provisions in GB980. If the purchaser stipulates that the coating must be subjected to corrosion resistance test, the cadmium-plated parts shall be tested in accordance with the provisions of GR6458. The corrosion resistance requirements of cadmium coating shall be agreed upon by the supply and demand parties. 11 Test methods
11.1 Thickness determination
11.1.1 Local thickness determination
GB/T 13346-92
The methods specified in GB6462, GB4955 and GB4956 are applicable to the thickness determination of coatings on steel. In addition, other thickness measurement methods suitable for coatings in GB6463 may also be used. When there is a dispute over the thickness measurement, the method specified in GB4955 shall be used, except for workpieces with an upper surface less than 100 mm (see the method specified in 11.1.2).
Note: (When the key layer is rough, the results measured by the microscopic method and the wheel smearing instrument method may have large errors, and the results measured by the cross-sectional method may be larger than the thickness value measured on the optical coating.
② Before measuring the thickness using the method specified in GB4955, a soft release material (such as lead oxide grinding paste) must be used to remove the chrome salt or other conversion film. Therefore, for thick conversion films, the measurement results will be slightly lower. 11.1.2 Determination of average thickness on small plated parts 11.1.2.1 Measuring method
When the area of the main surface of the plated part is less than 100mm2, measure the thickness of the base layer as follows: Take a sufficient number of parts so that the mass of the coating is not less than 100m. If the shape of the plated part is complex, the area should be agreed upon and approved by both parties. The plated part is weighed accurately to 0.0001 mm, and the coating is stripped at room temperature using a solution specified in 11.1.2.2. Wash the workpiece in running water and, if necessary, brush off the loose dark deposits on the surface (antimony deposits when using solution b or c). After careful drying, weigh and determine the lost mass. The thickness of the cadmium coating is calculated by the following formula, in units of m. d=m×10m
Where: m is the lost mass, mg
A——Area of the test surface, mm
β——Density of the cadmium coating, generally taken as 8.6 /cml11.1.2.2 Applicable stripping solution
Solution g, ammonium nitrate (NH4NO4) 300g/LSolution b: antimony trioxide (Sb2O3) 20g hydrochloric acid (p1.16/mL) 800 mL
water 200 mL
free liquid antimony trinitride (SbCls) 32g
hydrochloric acid (p≥l.16 g/mL) 800 mL
find 200 ml.
Dissolve the antimony dihydride or antimony dinitride in hydrochloric acid, and then dilute with water. When the bond layer is completely removed in solution b or, that is, when the violent chemical reaction stops, the workpiece should be removed from the solution immediately. After the removal reaction is over, if the workpiece is left in the solution for too long, the base metal may be corroded. Note: There is antimony trioxide and antimony trifluoride in the salt solution, so do not contact with the skin. ② When using solution b or, very toxic antimony trihydride gas will be released, which should be strictly prevented from being inhaled into the body and operated in a fume hood. Additional notes:
This standard is proposed and managed by the National Technical Committee for Standardization of Metal and Non-metallic Coatings. This standard was drafted by the 621st Institute and the 53rd Factory of the Ministry of Aeronautics and Astronautics. The main drafter of this standard is Sui Yongmo.
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