Find the most up-to-date version of ISO at Engineering ISOpdf – Download as PDF File .pdf) or read online. ASTM A method E is sometimes called the Strauss test, and is the same as ISO method A, except for the duration. As 15 hours is a difficult test period .
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As 15 hours is a difficult test period in practice, and is only a minimum, conducting the test for 20 hours overnight means that the two tests are equivalent. Where no specific test is specified, Isi 5 suggests the most appropriate alongside a second choice, if the first is declined. SEP also gives guidance on which of its methods apply to which alloys: None of these are identical and cross substitution of results is not possible.
Intergranular Corrosion Tests for CRAs
Where a bend test is required, the sample must be bent over a mandrel of a diameter related to the specimen diameter, without any cracking, as determined by inspection under a low power microscope and a microsection in any suspicious areas. There are a number of recognised tests when it comes to the intergranular corrosion testing of corrosion resistant alloys CRA.
This document describes all three of these tests for four common standards, and describes the differences. R Baboian, Corrosion Tests and Standards: Why were these tests designed? Hence, it is normally only used for stainless steels intended for nuclear service, or another application involving nitric acid.
Get in Touch Contact us by Phone or Email to find out how we can help your industry. Alternatively, a welded test-piece in the as-welded condition may be tested. ISO is specifically for duplex and all austenitic stainless steels, and recommends ageing at two different temperatures:.
It has been used for the duplex stainless steel UNS Swhich has been used for nitric acid cooler tubes. Contact us by Phone or Email to find out how we can help your industry. Test Samples Samples may be rectangular or cylindrical to suit the test vessel, but where a bend test is required, it is suggested that the sample be a minimum of mm long.
Both of these tests should be followed by water quenching.
Some standards require the test sample to be aged prior to testing, to simulate the precipitation that might occur during welding. When a test has been isp, follow the detailed directions in that standard for making up the test solution, the preparation of test samples and the finish to be used.
The Tests Table 1 below shows the various methods for four common standards: Bend test criteria for several standards. ASTM G28 lists alloys and specifies the test exposure for each.
Just remember that these tests were devised for specific groups of alloys and should not be applied to all CRAs! The most convenient size is often a cylinder 10mm diameter by mm long, but other dimensions are possible to suit particular product forms.
There ios other requirements in these standards over details that are not discussed in this document, and these should be followed, 3615-2 as conducting bend tests.
This document also points out which alloys the tests are intended for, and recommends the most appropriate test when none is specified. Where a standard is included in a purchase specification, this must be followed, although it is advised that unsuitable tests, such as the Huey test for duplex and super austenitic stainless steels, are queried.
ISO is the most rigorous in terms of defining test methods, and says which alloys should use which test methods as follows:. ASTM G28 method B is a more aggressive test than method A and is intended for more corrosion resistant alloys, as listed in the document. ASTM A was designed for austenitic stainless steels, specifically the series alloys.
All bend tests require a tensile test machine or similar, lso suitable grips and sufficient strength to bend the strongest alloy. For alloys not listed in this standard, it will be necessary to carry out some tests on material in various conditions to determine the threshold.
ASTM G28 was designed for nickel-based alloys, and a list of applicable alloys for methods A and B is in sio standard.
For an alloy that is not listed, look for an alloy with a similar composition to a listed alloy to determine the most suitable test. For many alloys, the onset is at 0. ISO is the most rigorous in terms of defining test methods, and says which alloys should use which test methods as follows: