JB/T 7901-2001 Laboratory uniform corrosion immersion test method for metal materials
Some standard content:
ICS77.060
Machinery Industry Standard of the People's Republic of China
JB/T79011999
Metals materials--Uniform corrosion-Methods of laboratory immersion testing
Metals materials--Uniform corrosion-Methods of laboratory immersion testing1999-08-06Published
National Bureau of Machinery Industry
2000-01-01Implementation
JB/T7901-1999
This standard is a revision of JB/T7901-95 "Metals materials laboratory uniform corrosion full immersion test method". During the revision, the original standard was edited and the main technical content remained unchanged. The appendix A and appendix B of this standard are both informative appendices. From the date of implementation, this standard will replace JB/T7901-95 at the same time. This standard is proposed and managed by the Technical Committee for Standardization of Instrument Function Materials. This standard was drafted by Chongqing Instrument Material Research Institute and Beijing Iron and Steel Research Institute. The main drafters of this standard are Wu Xiaoguang, Duan Guohua and Li Huiling. This standard was first issued in December 1988 (CB10124-88). 1 Scope
Mechanical Industry Standard of the People's Republic of China
Metal Materials Laboratory
Uniform Corrosion Immersion Test Method
Metals materiais-Uniform corrosion-Methods of laboratory immerson testingJB/T7901-1999bzxz.net
Replaces JB/T7901-95
This standard specifies the scope of application, reference standards, specimens, test equipment, test solutions, test time, test conditions and procedures, test results and test reports of the laboratory uniform corrosion immersion test method for metal materials. This standard is applicable to the evaluation of the uniform corrosion performance of metal materials in the immersion test. 2 Referenced Standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. At the time of publication of this standard, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. CB/T2481-1998 Detection and marking of abrasive grain composition for bonded abrasives GB/T4334.6-1984 5% sulfuric acid corrosion test method for stainless steel GB/T4334.8-1984 42% magnesium chloride stress corrosion test method for stainless steel CB/T8170-1987 Numerical rounding rules
3 Test specimen
3.1 Shape and size of the test specimen
3.1.1 The shape and size of the test specimen should be determined according to the original conditions of the test material and the test container used. The test specimen with a large surface area per unit mass and a small ratio of the side to the total area should be used as much as possible. In general, the area perpendicular to the rolling or forging direction shall not be greater than half of the total area of the test specimen. The surface area of each test specimen shall not be less than 10cm. 3.1.2 Two shapes of test specimens are recommended, and their specifications are as follows: Plate test specimens: Overall dimensions l×b×h, mm: 50×25×(2~5). Round test specimens: Overall dimensions @×h, mm: 30×(2~5). Test specimens of other shapes and sizes may also be used depending on the purpose of the test. 3.1.3 The shapes and specifications of the test specimens in the same batch of tests shall be the same. 3.2 Preparation of test specimens
3.2.1 When sampling from plates or strips, the samples shall be cut along the rolling direction. If the rolling direction is unclear or the samples are not cut along the rolling direction, it shall be noted in the report. The edges of the plates and strips shall be avoided as much as possible. 3.2.2 When sampling from round bars, the samples shall be cut longitudinally from the middle of the cross section of the bars. If the samples are cut radially, it shall be noted in the report. The sampling and preparation methods of castings, welded parts, deposited metal materials, etc. shall be determined by negotiation between the two parties to the test. 3.2.3 The specimen can be processed to the predetermined size by various mechanical methods, but any change in the performance of the specimen that may be caused by this must be avoided. When the shearing method is used, the sheared section needs to be reprocessed to remove the parts affected by shearing. 3.2.4 In order to improve the uniformity of the test results, the original metal surface layer can be removed by sandpaper grinding or other mechanical methods. The final surface of the specimen is ground with water sandpaper with a grit of 120 that meets the requirements of CB/T2481. Only specimens of the same material can be ground on the same sandpaper (cloth). However, the specimens for the test to examine the effect of the original metal surface on the corrosion rate are not included in this case. 3.2.5 When dry grinding is used in special circumstances, it must be noted in the report. 3.2.6 The corners of the specimen should be maintained, and chamfering is not allowed. 3.3·Other requirements for the specimen
3.3.1 If the specimen needs to be hung, it is allowed to drill a hole in the specimen, but the hole diameter should not be greater than 4mm3.3.2 When necessary, identification marks can be made on the specimen by appropriate methods. 3.3.3 The specimen after the final grinding treatment should be promptly degreased and washed with water, magnesium oxide powder paste, etc., and then degreased and washed with acetone, alcohol and other reagents that do not contain chloride ions. After rapid drying, it should be stored in a desiccator and placed at room temperature before measuring the area and weighing. 3.3.4·The calculation of the surface area of the specimen should be accurate to 1%. 3.3.5 When measuring dimensions, weighing and other operations, clean and oil-free measuring tools must be used, and clean working gloves must be worn. 3.3.6 When weighing, an analytical balance with an accuracy of not less than ±0.5mg should be used. 4 Test equipment
4.1 Container
4.1.1 The container material should be made of materials that are indifferent to the corrosive medium, and commonly used ones are glass, plastic, ceramic, etc. 4.1.2 When testing under boiling and high temperature conditions, a flask with a conical ground mouth and a reflux condenser with good cooling effect can be used. It is recommended to use the containers shown in GB/T4334.6 and GB/T4334.8. 4.1.3 When testing at room temperature, a properly sealed container can be used. 4.2 Temperature maintenance system
According to different temperature requirements, a temperature maintenance system that can keep the test solution within the specified temperature range should be selected. 4.3 Sample support system
4.3.1 The sample support system should be able to support the sample in the middle of the test solution. The material of the support system should be compatible with the test solution and the sample, and the contact area between it and the sample should be as small as possible.
4.3.2 In general, a glass bracket or hook is used, and a support system made of plastic, ceramic, chemical fiber, etc. can also be used. 4.4 Other devices
During the test, if the test solution needs to be stirred or continuously flowed and replenished, the corresponding device must be designed and added according to the actual situation to meet the test requirements.
5 Test solution
5.1 The source and composition of the test solution depend on the purpose of the test. Generally, there are two types: natural and artificial. Seawater, industrial wastewater and media in the production process are generally classified as natural media. When using this type of solution, its main components need to be determined. 5.2 When preparing the solution, use distilled water or deionized water and reagents of analytical grade that meet national standards or industry standards. If other levels of reagents are used, it must be stated in the report. 5.3 The concentration of the solution is expressed in weight percentage. If it is expressed in other ways, it must be indicated. 5.4 Other parameters such as pH value and dissolved gas content shall be agreed upon by both parties to the test. 5.5 The amount of test solution used is not less than 20mL per cm2 of sample surface area. 5.6 The temperature control accuracy of the test solution should be within ±1℃. When testing at room temperature, the upper and lower limits of the actual temperature during the test and the average temperature value should be stated in the report.
5.7 If the solution is to be aerated, avoid spraying the airflow directly on the sample. This operation must be started at an appropriate time before the sample is placed in the test and must be continued throughout the test. If dissolved oxygen needs to be removed, insulated gas (such as nitrogen) can be used for inflation. 2
6 Test time
JB/T7901-1999
6.1 The test time refers to the entire time from when the sample enters the solution and reaches the specified temperature until the sample is taken out. 6.2 The determination of the test time depends on the size of the corrosion rate and whether the test material can form a passivation film in the test solution. Under normal circumstances, the results of long-term tests are more accurate, but materials that are severely corroded do not require a long test time. For materials that can form a passivation film, under extreme conditions, the test time needs to be extended to obtain more realistic results. 6.3The most commonly used test cycle is 48h168h. Please refer to Table 1 for specific selection. Table 1 Selection of test time
Estimation or prediction of corrosion rate
Test time
72-168
168~336
336~720
Note: *\The predicted test time is 24h, and the liquid volume is 20mL/cml. Replacement of solution or not
No replacement
No replacement
Replace once every 7 days
Replace once every 7 days
6.4 If the solution needs to be replaced during the test, the operation should be quick and the sample does not need to be processed. The test time is calculated cumulatively from the time the specified temperature is reached again.
6.5 If you need to understand the influence of the test time on the metal corrosion and the corrosiveness of the medium and determine the best test cycle, you can use a planned intermittent corrosion test method, see Appendix A.
7 Test conditions and steps
7.1 According to 5.5, take an appropriate amount of solution and place it in a fully washed test container. 7.2 Pour the sample completely into the solution: You can also place the sample in the container first and then pour the solution. When the solution needs to be degassed or inflated, the sample must be ventilated for at least 0.5h (depending on the amount of solution) before being placed in the solution. 7.3 Take at least three parallel samples for each test. 7.4 The sample should be placed in the middle of the solution as much as possible and is not allowed to contact the container wall. Generally, only one sample can be placed in each container. If more than two samples are required, the distance between the samples should be more than 1cm. 7.5 Use a temperature maintenance system to make the solution reach the specified temperature as soon as possible. At this time, the timing starts. 7.6 During the boiling test, the solution should be kept in a slightly boiling state. To prevent violent boiling, appropriate boiling aids can be added, such as small glass balls, ceramic eyebrows or polytetrafluoroethylene chips.
7.7 During the test, the changes in the sample and solution should be observed frequently and recorded. 7.8 After the predetermined time has elapsed, take out the sample, rinse it with water, and then wipe off the corrosion products with a brush, rubber tool, etc., or remove them with ultrasonic or other methods, see Appendix B.
7.9 After the sample is cleaned by the above method, treat it according to 3.3.3 and 3.3.6. 8 Test results
8.1 This standard uses corrosion rate as the expression form of test results. If the material has local corrosion, it shall be treated according to the relevant test method.
The corrosion rate is calculated as shown in formula (1):
Wherein: R——corrosion rate, mm/a;
M—mass of the sample before the test, g;
M,——mass of the sample after the test, g;
S—total area of the sample, cNR;
T—test time, h;
JB/T7901-—1999
R-8.76×10x(MM)
D-.Density of the material, kg/m.
8.3For some metals (such as titanium, etc.), their corrosion products are a layer of solid and dense oxide, which is difficult to remove by chemical or general mechanical methods. In this case, the weight-gain corrosion rate can be used to express the test results. 8.4Sometimes, for some special needs, the test results can also be expressed in other units of magic corrosion rate, but it needs to be stated in the report. 8.5 The corrosion rate is reported as the average value of all parallel samples tested: When the relative deviation between the corrosion rate of a parallel sample and the average value exceeds 10%, a new sample should be taken for repeated testing and the second test result should be reported. If the requirement is not met again, the average value of all samples in the two tests and the corrosion rate of each sample should be reported at the same time. However, this does not apply when the corrosion rate is less than 0.1mm/a. In this case, the corrosion rate of all samples should be reported.
8.6 The corrosion rate obtained in this test can only be used to evaluate the corrosion resistance of the tested material in a certain test medium, and cannot be used to refer to the corrosion resistance of this material in other media.
8.7 When the measured and calculated values need to be rounded off, they shall be handled in accordance with the relevant provisions of GB/8170. 9 Test report
The test report should include the following:
The brand (code), chemical composition and state of the sample material; the composition, temperature and test time of the test solution; the phenomena and corrosion rate that occurred during the test; the cleaning method of the corrosion products on the sample;
Corrosion rate or weight gain corrosion rate:
Remarks for situations that need to be noted;
The signature of the operator and reviewer;
Report date.
A1 Test purpose
JB/T7901—1999
Appendix A
(Suggestive appendix)
Planned intermittent corrosion test method
To examine the effect of test time on solution corrosivity and metal corrosion rate, and to select the best test cycle based on this. A2 Test method
A2.1 Take four groups of samples, each with at least two pieces. The four groups of samples are placed in the medium of the same container for testing. If the container is not large enough, one sample can be taken from each group and placed in one container for testing, or two containers can be used for parallel testing under the same conditions. A2.2 The test time of the four groups of samples is arranged according to Figure AI: Group I
Test time (h)
That is, Groups I, II, and III start the test at the same time, Group I is a full-time test (test time is! + α), Group II is a long-term test (test time is t), and Group III is a short-term test (test time is.). When the test is carried out to:, the sample of Group IV is placed in the above solution to start the test, and the test time is b (b=a).
A2.3 All tests are carried out in accordance with this standard, and the corrosion losses (weight loss per unit area) of the four groups of samples are used as the basis for evaluation. A2.4 Evaluation
A2.4.1 Let R., R,, R. and R. be the corrosion losses of the samples of Groups I, II, III, and N, respectively, and R. =R,+. -R.A2.4.2
The conditions during the test are determined according to Table A1 and Table A2. Table A1 Conditions during the corrosion test
Corrosivity of the solution
Metal corrosion rate
No change
No change
Corrosivity of the solution
No change
No change
No change
JB/T7901-1999
Table A2 Comprehensive evaluation table
Metal turbidity rate
No change
No change
No change
R.3 For some metals (such as titanium, etc.), their corrosion products are a layer of solid and dense oxides, which are difficult to remove by chemical or general mechanical methods. In this case, the test results can be expressed by weighted corrosion rate. 8.4 Sometimes for some special needs, the test results can also be expressed in other units of magic corrosion rate, but it needs to be explained in the report. 8.5 The corrosion rate is reported as the average value of all parallel samples tested: When the relative deviation between the corrosion rate of a parallel sample and the average value exceeds 10%, a new sample should be taken for repeated testing and the second test result should be reported. When the requirements are not met again, the average value of all samples in the two tests and the corrosion rate of each sample should be reported at the same time. However, this is not the case when the corrosion rate is less than 0.1mm/a. At this time, the corrosion rate of all samples should be reported.
8.6 The corrosion rate obtained in this test can only be used to evaluate the corrosion resistance of the tested material in a certain test medium, and cannot be used to refer to the corrosion resistance of this material in other media.
8.7 When the measured and calculated values need to be rounded off, they shall be handled in accordance with the relevant provisions of GB/8170. 9 Test report
The test report should include the following:
The brand (code), chemical composition and state of the sample material; the composition, temperature and test time of the test solution; the phenomena and corrosion rate that occurred during the test; the cleaning method of the corrosion products on the sample;
Corrosion rate or weight gain corrosion rate:
Remarks for situations that need to be noted;
The signature of the operator and reviewer;
Report date.
A1 Test purpose
JB/T7901—1999
Appendix A
(Suggestive appendix)
Planned intermittent corrosion test method
To examine the effect of test time on solution corrosivity and metal corrosion rate, and to select the best test cycle based on this. A2 Test method
A2.1 Take four groups of samples, each with at least two pieces. The four groups of samples are placed in the medium of the same container for testing. If the container is not large enough, one sample can be taken from each group and placed in one container for testing, or two containers can be used for parallel testing under the same conditions. A2.2 The test time of the four groups of samples is arranged according to Figure AI: Group I
Test time (h)
That is, Groups I, II, and III start the test at the same time, Group I is a full-time test (test time is! + α), Group II is a long-term test (test time is t), and Group III is a short-term test (test time is.). When the test is carried out to:, the sample of Group IV is placed in the above solution to start the test, and the test time is b (b=a).
A2.3 All tests are carried out in accordance with this standard, and the corrosion losses (weight loss per unit area) of the four groups of samples are used as the basis for evaluation. A2.4 Evaluation
A2.4.1 Let R., R,, R. and R. be the corrosion losses of the samples of Groups I, II, III, and N, respectively, and R. =R,+. -R.A2.4.2
The conditions during the test are determined according to Table A1 and Table A2. Table A1 Conditions during the corrosion test
Corrosivity of the solution
Metal corrosion rate
No change
No change
Corrosivity of the solution
No change
No change
JB/T7901-1999
Table A2 Comprehensive evaluation table
Metal turbidity rate
No change
No change
No change
R.3 For some metals (such as titanium, etc.), their corrosion products are a layer of solid and dense oxides, which are difficult to remove by chemical or general mechanical methods. In this case, the test results can be expressed by weighted corrosion rate. 8.4 Sometimes for some special needs, the test results can also be expressed in other units of magic corrosion rate, but it needs to be explained in the report. 8.5 The corrosion rate is reported as the average value of all parallel samples tested: When the relative deviation between the corrosion rate of a parallel sample and the average value exceeds 10%, a new sample should be taken for repeated testing and the second test result should be reported. When the requirements are not met again, the average value of all samples in the two tests and the corrosion rate of each sample should be reported at the same time. However, this is not the case when the corrosion rate is less than 0.1mm/a. At this time, the corrosion rate of all samples should be reported.
8.6 The corrosion rate obtained in this test can only be used to evaluate the corrosion resistance of the tested material in a certain test medium, and cannot be used to refer to the corrosion resistance of this material in other media.
8.7 When the measured and calculated values need to be rounded off, they shall be handled in accordance with the relevant provisions of GB/8170. 9 Test report
The test report should include the following:
The brand (code), chemical composition and state of the sample material; the composition, temperature and test time of the test solution; the phenomena and corrosion rate that occurred during the test; the cleaning method of the corrosion products on the sample;
Corrosion rate or weight gain corrosion rate:
Remarks for situations that need to be noted;
The signature of the operator and reviewer;
Report date.
A1 Test purpose
JB/T7901—1999
Appendix A
(Suggestive appendix)
Planned intermittent corrosion test method
To examine the effect of test time on solution corrosivity and metal corrosion rate, and to select the best test cycle based on this. A2 Test method
A2.1 Take four groups of samples, each with at least two pieces. The four groups of samples are placed in the medium of the same container for testing. If the container is not large enough, one sample can be taken from each group and placed in one container for testing, or two containers can be used for parallel testing under the same conditions. A2.2 The test time of the four groups of samples is arranged according to Figure AI: Group I
Test time (h)
That is, Groups I, II, and III start the test at the same time, Group I is a full-time test (test time is! + α), Group II is a long-term test (test time is t), and Group III is a short-term test (test time is.). When the test is carried out to:, the sample of Group IV is placed in the above solution to start the test, and the test time is b (b=a).
A2.3 All tests are carried out in accordance with this standard, and the corrosion losses (weight loss per unit area) of the four groups of samples are used as the basis for evaluation. A2.4 Evaluation
A2.4.1 Let R., R,, R. and R. be the corrosion losses of the samples of Groups I, II, III, and N, respectively, and R. =R,+. -R.A2.4.2
The conditions during the test are determined according to Table A1 and Table A2. Table A1 Conditions during the corrosion test
Corrosivity of the solution
Metal corrosion rate
No change
No change
Corrosivity of the solution
No change
No change
JB/T7901-1999
Table A2 Comprehensive evaluation table
Metal turbidity rate
No change
No change
No change
R.
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