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G48 contains six different test methods for evaluating the pitting and crevice corrosion resistance of stainless and nickel alloys.
These are:. However, these parameters can be modified to suit individual test needs. Note that these are not acceptance tests as written in G48 as there are no acceptance criteria.
They can be used as acceptance tests if criteria e. Methods C through F are designed as incremental tests and require multiple specimens. These tests identify the minimum critical temperature needed to initiate pitting or crevice corrosion.
There are no acceptance criteria for any alloys. These tests offer a means to evaluate and compare the expected performance of various alloys. Because of the extensive testing required and time consuming nature, these tests are generally not used for production testing, even when acceptance criteria are provided.
A actually contains three different test methods for determining acceptability. Test Method C in A is a ferric chloride pitting test. Alloy material tested in a 6 wt.
The pH is adjusted to 1. However, since the tests are slightly different, material tested in accordance with one method cannot be certified to the other without re-testing. Because of the wide experience in the production testing of duplex alloys, testing in accordance with A is recommended. Return to Blog List. CCT L Our Company. North America Asia Europe. United States P. All Rights Reserved.
Pitting and Crevice Corrosion Testing
Historical Version s - view previous versions of standard. More G The results may be used for ranking alloys in order of increasing resistance to pitting and crevice corrosion initiation under the specific conditions of these methods. Methods A and B are designed to cause the breakdown of Type at room temperature. No statement can be made about resistance of alloys in environments that do not contain chlorides. Consequently, the degree of corrosion damage that occurs during testing will generally be greater than that in natural environments in any similar time period.
When using stainless and duplex steels, ASTM G48 is widely used to ensure the quality of the material and resistance to pitting and crevice corrosion. ASTM G 48 is a relatively severe test, but lack of definition in the standard can lead to variation of data. We follow a standard practice we have developed to minimize these variations and provide consistent data. However, the G48 test is meant for ranking or qualification, and not as designed for determining a corrosion rate over time. There are 6 Methods: A and B are for qualification of alloys to pitting and crevice corrosion at specific temperatures, C and D are for determining the critical pitting and crevice corrosion temperatures of chromium and nickel alloys, and E and F are for stainless alloys. Which one do you need? The answer is: it depends.