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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ASTM G28 does not require samples to be heat treated. It does not say what to do about isoo or super austenitic alloys. The test solutions and exposures for some common intergranular corrosion tests.
For many alloys, the onset is at 0.
Intergranular Corrosion Tests for CRAs
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. This test should be avoided for most CRAs, except in the circumstances described below, in section 4. ASTM A was designed for austenitic stainless steels, specifically the series alloys.
These tests were introduced when the carbon content in CRAs typically hit 0. SEP also gives guidance on which of its methods apply to which alloys: There are other requirements in these standards over details that are not discussed in this document, and these should be followed, such as conducting bend tests.
Why were these tests designed? 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. The test methods in Table 1 were designed with specific alloys in mind, but the proliferation of new CRAs has meant that the selection of a suitable test method is difficult.
The Huey test method C is only for molybdenum-free grades, such as L, as alloys with molybdenum show high rates of attack in this test. This document describes all three of these tests oso four common standards, and describes the differences. Hence, it is normally only used for stainless steels intended for nuclear service, or another application involving nitric isso. None of these are identical and cross substitution of results is not possible. ISO is the most rigorous in terms of defining test methods, and says which alloys should use which test methods as follows:.
The latter is a German test, but it is often called up in European projects.
The Tests Table 1 below shows the various methods for four common standards: More suitable alternatives are offered in Table 5, below. Both of these tests should be followed by water quenching. ISO is specifically for duplex and jso austenitic stainless steels, and recommends ageing at two different temperatures:. Methods B and E are suggested for all grades of series austenitic alloys, while method F is suggested for cast type alloys.
Conducting the Tests When a test has been selected, 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 specifications for bend testing are shown in Table 4. Contact us by Phone or Email to find out how we can help your industry.
Where isp 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. 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.
The exception to this is ASTM G28 method A, where rates for the onset of intergranular corrosion are described in reference 1. It has been used for the duplex stainless steel UNS Swhich has been used for nitric acid cooler tubes. 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.
Selection of a Test Method The test methods in Table 1 were designed with specific alloys in mind, but the proliferation of new CRAs has meant that the selection of a suitable test method is difficult.
ISO is the most rigorous in terms of defining test methods, and says which alloys should use which test methods as follows: There are a number of recognised tests when it comes to the intergranular corrosion testing of corrosion resistant alloys CRA.
ISO is specifically for duplex and all austenitic stainless steels, and recommends ageing at two different temperatures: Table 1 below shows the various methods for four common standards: SEP does not require ageing, although it might be required in a specification calling up this standard.
Good material should have a corrosion rate substantially less than the threshold value. The effect of post weld surface treatments on the corrosion resistance of super duplex stainless steel welds in sea water Bend test criteria for several standards.
Make an Enquiry Notice: Just remember that these tests were devised for specific groups of alloys and should not be applied to all CRAs! All bend tests require a tensile test machine or similar, with suitable grips and sufficient strength to bend the strongest alloy.