The ASTM G31-21 standard, published by the American Society for Testing and Materials (ASTM), describes the factors affecting laboratory immersion corrosion tests, especially mass loss tests. These factors include apparatus, sampling, test specimen, test conditions (such as test solution composition, temperature, gas scattering, fluid movement, solution volume, method of supporting test specimens, test time), methods of cleaning test specimens, interpretation of results, and corrosion. calculation of rates. This standard also emphasizes the importance of recording all relevant data and provides a checklist for reporting test data. Specific assessment of the effects of localized attack, environment-assisted cracking and solution flow is not covered by this standard.
The ASTM G31-21 standard is intended for use by those who design laboratory immersion tests who are unfamiliar with all the variables to consider. Corrosion tests, by their very nature, preclude full standardization. In this regard, this standard is presented as a guideline so that some of the pitfalls of such tests can be avoided, rather than a standard procedure.
Experience shows that not all metals and alloys respond in the same way to many factors that affect corrosion, and accelerated corrosion tests are only indicative or even completely misleading. Therefore, one purpose of this standard is to encourage better correlation of results in the future and the reduction of conflicting reports through more detailed recording of significant factors and conditions.
The immersion corrosion test is used to determine the resistance of a material to an aqueous environment. It is based on determining the weight loss due to corrosion. The test method described in ASTM G31 normalizes corrosion rates to time units, typically in mm/year. The test temperature and oxygen availability variables are specific to the test being performed. Results are generally achieved within a 24-hour, 10-day, or 20-day exposure cycle. After testing, gravimetric analysis provides the corrosion weight. Surface analysis can also be performed to further investigate the post-test morphology.
Among the numerous test, measurement, analysis and evaluation studies it provides for businesses in various sectors, our organization also provides standard testing services for immersion corrosion testing of metals in the laboratory, within the scope of ASTM G31-21 standard, with its trained and expert staff and advanced technological equipment.
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