Methods for corrosion testing of metallic and other inorganic coatings on mtallic substrates--Rating of test speciments and manufactured articles subjected to corrosion tests
Some standard content:
ICS 25.220. 20
National Standard of the People's Republic of China
GB/T64612002
Replaces GB/164611986
GB/T123351990
Methods for corrosion testing of metallic and other inorganic coatings on metallic substrates-Rating of test specimens and manufactured articles suhjected to corrosion tests(ISO 10289:1999. IDT)
2002-09-11 Issued
People's Republic of China
General Administration of Quality Supervision, Inspection and Quarantine
2003-04-01 Implementation
Terms and definitions
Defect types
Test methods
6 Rating cousin
Test report
Appendix A (informative appendix) Dot diagram and color photograph of cathodic coating on base metal Appendix B (informative appendix) Dot diagram of anodic coating on base metal References
GB/T 6461—2002
GB/T 6461—2002
This standard adopts IS0102891099 Rating of specimens and test pieces after corrosion tests of metallic and other inorganic coatings on metallic substrates (English version).
This standard is translated from the international standard and this standard is translated based on the English version of the international standard. The following modifications have been made to facilitate the use of this standard: - "This standard" is used instead of "this international standard"; - The foreword of the international standard is cancelled. - This standard replaces GB/T6161-198 Rating of electroplated specimens after corrosion tests of metallic coatings on substrates with anodic coatings and GB/T12335-990 Rating of specimens after corrosion tests of metallic coatings on substrates with anodic coatings. Compared with GB/T6461-1986 and GR/T12335-990, the main changes of this standard are as follows: the dot diagram of the anodic coating on the substrate is more in line with the shape of the notch of the specimens and test pieces after the corrosion test, and the Appendix A of the original GB/T12335 is deleted; - Chapter 6 of this standard is more consistent with the original GB/T12333 Chapters 5 and 6. Chapter 7 and Chapters 4, 5, 6 and Appendix A of the original GB/T6461 have been greatly modified to make the content more complete and clear. This standard changes Article 3.4 of the original GB/T6461 and Article 4.5 of the original GB/T12335 "within 6mm of the edge of the specimen" to "within 5mm of the edge of the specimen or tape/wax"... The Appendix A and Appendix B of this standard are informative appendices. This standard was proposed by the China Machinery Industry Federation. This standard was issued by the National Technical Committee for Standardization of Metal and Non-metallic Materials. The drafting unit of this standard: Wuhan Institute of Materials Protection The main drafters of this standard: Zhang Yan, Li Zhi, Wang Yaping, Sun Yong, Shi Lai Zao, Zhang San. The previous versions of the standards replaced by this standard are: GR/T6461-1986. GB/T12335-1990. GB/T 6461--2002
The rating method described in this standard applies to metallic and inorganic coatings that are applied and protective to the metal substrate, whether it is anodic or cathodic to the substrate. The corrosion resistance of these coatings is rated from two aspects: the ability of the coating to protect the substrate from corrosion damage; the ability of the coating to maintain its integrity and maintain a satisfactory appearance. Although the above functions are mutually exclusive, they can be evaluated separately using the following indicators: - Protection rating () related to corrosion of the base metal; - Appearance rating (RA) related to damage to the coating. The protection rating (K) is a number that describes the ability of the coating to protect the base metal from corrosion. The appearance rating (R) is a letter and number that describes the overall appearance of the specimen, including the appearance of the specimen. All damage caused by the corrosion test or the environment. Note 1: Defects of the corrosion test inserts or test pieces should be recorded and taken into account when evaluating the test results. Prefabricated defects can also be part of the test plan.
If this rating system is used, the coating system must be known and reported. If possible, it should be determined whether the micro-coating is anodic or cathodic to the base metal.
Note 2: In certain cases (for example, chromium-formaldehyde conversion models or multi-layer coatings on the surface of the surface of the defect are very strong) When determining the mechanisms of anodic and cathodic corrosion, the implementation of the technical standard does not require understanding of these mechanisms. 1 Scope
Rating of specimens and test pieces after corrosion tests of metals and other inorganic coatings on metal substrates GB/T 6461--2002
This standard specifies methods for assessing the corrosion state of test panels or test pieces covered by decorative and protective metal and inorganic coatings after being subjected to drop tests or other exposure in a commercial environment. The methods specified in this standard are applicable to test panels or test pieces exposed to dynamic or static conditions in a natural atmosphere. They are also applicable to test panels or test pieces subjected to accelerated tests.
Note 1: For examples, see this standard.
This standard assumes that the protection rating is made objectively as specified in Chapter 6, while the appearance rating is determined by a number of subjective considerations (see 6.21).
Note 2: The edges of the test panels or test pieces may need to be protected, for example with glue or wax. If this protection is agreed upon in the test, it should be recorded in the test report. When the specimen is cut from a part and the part is not fully covered, protection is not necessary. 2 Terms and Definitions
The following terms and definitions apply to this standard. 2.1
Profection Rating
The protection rating number (see Table 1) indicates the ability of the die casting to protect the base metal from corrosion. 2.2
Protection Defects
Proteclide Defects
Defects associated with the protection rating include pits, pores, corrosion spots caused by base corrosion, blisters, and other defects caused by corrosion of the base metal.
Note: Blisters on lead and zinc alloy die castings and electroplated coatings usually indicate corrosion of the base metal. The inspector determines whether the blister is found at the interface between the base metal and the coating.
Appearance rating
appcarancc rating
The rating number (see Table 1) and code (see Table 2) describe the entire appearance of the specimen: including all defects caused by exposure. 2.4
appearancedefect
Appearance defect
Defect that damages the appearance of the specimen (see 2). 2.5
Performance rating
performinceralingbzxZ.net
The combination of the protection rating number (K) followed by a slash and then the appearance rating number (K,). That is, K/R2.6
Coating system
coating system
GB/T6461—2002
Special deposition series, including the thickness and type of each layer of multi-layer deposition and the treatment of the base metal. 2. 7
Major surfacesignificant surfacc
Part 1 The part of the surface that has been covered or is to be covered by the coating, which is important for the external appearance or performance of the workpiece (see Chapter 3).
3 Principle
The standard provides a rating system for evaluating the corrosion damage of the coating and the base metal. The rating method described in the standard is used to evaluate the appearance of the coating and the degree of corrosion of the main surface of the test plate or test piece after the performance test. The surface inspection results are recorded using two independent ratings, protection rating R and appearance rating (R), which are called performance ratings.
When recording the surface rating of the specimen, if the type and severity of the defect are to be indicated, the agreed defect type code and defect severity code are used to record this information.
When only the protection rating (R) is required, the appearance rating (R.) can be omitted. The method of indicating H is to follow the protection rating with a short dash (R/).To indicate that the appearance rating has been omitted. 4 Defect Types
Defects may affect both the protection rating (R) and the appearance rating (R). In this rating system, the protection rating is a simple numerical rating, while the appearance rating may include the specific defect and a numerical rating indicating its severity. A list of defects is shown in Table 2. This list may also be supplemented when recording specific defects. Defects are pitting, pinhole corrosion, general corrosion of the coating, corrosion products, blistering and any other defects in the coating. Some defects, such as blistering, may be related to the coating, the base metal, the interface between the coating and the base metal, or the interface between layers in the coating. Other defects, although only slight corrosion, have a significant effect on the appearance, such as spots, gloss loss, cracks, etc. Although sophisticated mechanical treatment methods are used, defects on the surface of the base metal, such as scratches, pores, non-conductive inclusions, rolling and die marks, cold shuts and lines, etc., will still have a negative impact on the performance of the coating. Such defects should be recorded and rated separately. Because the reproducibility of some defects may depend on whether the capping layer is anodic or polar to the base metal, the capping system should be carefully recorded.
Attention should be paid to the development of defects in the exposure, such as peeling or detachment of the coating layer. This indicates that there may be problems with the pretreatment of the base metal or the coating.
5 Inspection method
Use a pattern or appropriate marking to indicate the main surface of the specimen. Before conducting environmental tests, it is necessary to find out the material with defects in some aspects and make records. If the surface is damaged before the pre-test, this damage should be recorded and reported truthfully. If the specimen is intentionally deformed, the deformed area should be rated separately.
The specimen can be inspected on the exposure rack or moved to an appropriate place for inspection. The light should be as uniform as possible during inspection, avoiding direct sunlight reflection or cloud cover, and inspect from different angles to ensure that the defects are fully revealed. After the test, if the specimen is in a satisfactory condition, it can be inspected without cleaning. If dirt and salt deposits etc. obscure defects and make inspection difficult, it is advisable to rub the surface with a sponge dipped in neutral detergent solution and then rinse with water. It is recommended that pressure should not be applied during this process to avoid washing away corrosion products and causing a high rating. The cleaning solution should not cause any damage to the covering layer. Do not wash the sample during the mid-term or regular inspection, otherwise it will interfere with the corrosion behavior of the test piece: the sample should be allowed to dry after cleaning before inspection. This should be explained when rating the surface. The defects counted are those visible to normal or corrected vision. 2
Note 1: After the initial inspection, the characteristics of the defects can be further described with the help of optical instruments. GB/T 6461---2002
Edge defects within 5mtl of the test piece edge or tape/wax can be noted in the report, but should not affect the numerical rating. Similarly, defects such as contact marks, hanger marks and fixing holes can be ignored: Note 2: Edge defects on deeply processed specimens, such as cracks, holes, etc., can be evaluated. In this case, the specific defect area to be determined can be agreed upon by the strip owner and the supplier.
When the micro-coating is of the same polarity as the base metal, the development of concave corrosion products from the edge of the specimen is not considered to be a failure of the coating. Sometimes the surface of the specimen is rubbed, mopped, chemically cleaned, etc. to study the surface - such treatment should be limited to the smallest possible area. For a 10mm×150mm specimen, the treatment area should preferably not exceed 100mm. This area for continued test rating should be stated.
6 Expression of ratings
6.1 Expression of protection rating (K,)
The numerical rating system is based on the area of the base material of the defect, which is calculated as follows: Rr = 3(2 - logA)
Where:
R - rounded to the nearest integer - as listed in Table 1: A - percentage of the area of the base metal etched
Note: In some cases, it may be difficult to calculate the exact area, especially for specimens with increased depth such as threads and holes. In this case, the inspector should calculate the area as accurately as possible.
For specimens with extremely small defect areas, strictly following formula (1) will result in a rating greater than 19. Therefore, formula (1) is limited to specimens with an area of A greater than 0.016416. For surfaces without base metal corrosion, a rating of 10 is arbitrarily defined. If necessary, the ratings listed in Table 1 may be used with the score values [x points]. Note 2: When using certain pre-coating systems that require anodic properties for metal alloys, it may be difficult to assess the true protection rating due to the formation of large amounts of corrosion products in the coating. Due to the high viscosity of these corrosion products, they tend to cover the surface corrosion of the base metal. For example, zinc coatings on steel in salty atmospheres. Although this standard can be used to rate the performance of zinc micro-coating, it may be difficult to determine the protection rating in some environments. If the defects are very concentrated, use the dot chart or photo standards listed in Appendix A and Appendix H. You can also use two flexible stencils of [mm×1mm.2mm<2mm or 5mm×5m to evaluate the corrosion surface. If a large group of samples is to be tested at the same time, it is recommended to evaluate them one by one according to formula (1). "After the whole group of samples is rated, each rating should be reviewed to ensure that each rating can truly reflect the degree of defects in the sample. The review serves to verify each rating and helps to ensure that the judgement or reference system of the inspector does not change due to factors such as changes in lighting conditions or fatigue during the inspection process. The following scheme can be used for inspection:
a) Take out the samples one by one from the exposure rack and then compare the samples between categories:) Arrange all samples in order of goodness and badness.
Protection rating (R) and appearance rating (R,
Defects
Light defects
.1: 0.1
, 1.4520. 25
0.25A.0. 5
0. 5-A81.0
1. 0.1,2. 5
GB/T 6461—2002
Defective surface area
2. 54.5. 0
Examples of using this method to assess the protection rating R: Capsule {Continued
a) Slight rust exceeding the requirements of Table 1. Less than 25% of the surface: /6) No defects: 10/-
6.2 Expression of appearance rating (R)
The appearance rating is assessed as follows:
The type of defect determined by the classification given in Table 2 and the area affected by a defect determined by the grades listed in Table 1 (1-~0): The main factor affecting the degree of damage Visual evaluation: For example: VS - very mild;
$ = mild:
m = moderate:
x - severe:
Table 2 Classification of types of cover damage
Rp or RA
Spots and (or) color changes caused by cover damage (different from the color of obvious corrosion products) are rarely seen or even invisible. Cathodic corrosion products caused by polar corrosion Corrosion products of the layer
Surface pitting (corrosion pits may not extend to the base metal) chipping, peeling and flaking
Chicken claw or star-shaped defects
Examples of using this method to assess the appearance rating (K): a
Moderate spotting - area exceeds 20Cold: -/2mA: Mild corrosion of the covering layer (anodic), area exceeds 1%: -/5sC: Very small surface pits cause slight damage to the entire surface: /05B, vsE, Note, appearance The rating (R) may include more than one defect, in which case each defect shall be reported separately (see example in 6.3e). 6.3 Expression of performance ratings
As described in 2.5. The performance rating is a combination (R/R) of the protection rating (R>) followed by a slash and the external rating (R). Examples of performance ratings:
The specimen has more than 0.1% of the total area of base metal corrosion and the remaining surface of the specimen has more than 20% of this area of moderate spotting: 9/2 m AF
The sample has no base metal corrosion, but has slight corrosion of the anodic coating of less than 1.0% of the total area: 10/6s (GB/T 6461-2002
The sample has a poor area and the base metal corrosion (=7), the corrosion products of the anodic coating have a total area of
0.15%, and the electrodeposition layer on the surface has a slight bulging of more than 0.75% of the total area (extended to the base metal): 7/8 v C.6 m G
Test report
Unless circumstances require, the test report shall include the following: test conditions, such as those specified in a standard; a
Exposure period, if known or estimated;
Description of the coating system and base metal or product under test; d)
Report on the assessment of the results obtained in R;
Size and shape of the test specimens or test pieces;
Preparation method used for the surfaces to be evaluated, including any cleaning treatment used, any protection of edges or other special areas, and any pre-test preparations; Number of test specimens or test pieces representing each coating or product; g
Washing method of the test specimens or test pieces after the test, if required; Protection rating (Rp) and appearance rating (R) (performance rating according to 6.1 and .2, respectively) for each test specimen or test piece; g
Report on the results obtained in R 6461—2002
A.1 General
Appendix A
(Informative Appendix)
Dot diagrams and color photographs of cathodic coatings on base metal - These diagrams and photos represent the maximum amount of base metal corrosion allowed for a given rating. Each rating has a diagram or photo from 1 to !, unless there is a sub-rating between 1 and !. Otherwise, a sample worse than the diagram or photo of 1 is rated as !. A.2 Use of dot diagrams
When using dot diagrams or photos, it is recommended to place the corresponding diagram or photo next to the surface being inspected and make the defect as close as possible to one of the ratings. If the surface being inspected is worse than (?) but not as good as (?), it is rated as (?): If the surface is slightly worse than (?) but better than (?) grade, then Rated as (-1). The type of corrosion defects encountered may vary depending on the type of atmospheric exposure and the type of overburden during the test. Therefore, in some cases it is best to use a dot diagram; in other applications, a color photograph may be more appropriate; however, in some cases, direct measurement may be beneficial for assessing the affected area.
In general, dot diagrams are more suitable for assessing the extent of industrial atmospheric corrosion. Photographs are more helpful in assessing the extent of marine atmospheric corrosion. Each of the six square diagrams represents one of the ratings for the area of corrosion. It uses a graph to show the number of corrosion spots. 1) Dot diagram color photographs provided by the American Society for Testing and Materials (ASTM), LuEarrarho Drive, westGonshubocken.Fennysylainia1342251
GB/1 6461
GB/T 6461
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