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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The specifications for bend testing are shown in Table 4. Good material should have a corrosion rate substantially less than the threshold value. This test should be avoided for most CRAs, except in the circumstances described below, in section 4. 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.
Methods B and E are suggested for all grades of series austenitic alloys, while method F is suggested for cast type alloys. Make an Enquiry Notice: SEP also gives guidance on which of its methods apply to which alloys: ASTM G28 lists alloys and specifies the test exposure for each. It does not say what to do about duplex or super austenitic alloys.
All 36551-2 tests require a tensile test machine or similar, with suitable grips and sufficient strength to bend the strongest alloy. Suggested test methods for different corrosion resistant alloys. ASTM A was designed for austenitic stainless steels, specifically the series alloys. More suitable alternatives are offered in Table 5, below.
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. 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. 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.
Some suggested criteria for the listed alloys are shown in Table 2, below.
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. This document also points out which alloys the tests are intended for, and recommends the most appropriate test when none is specified.
SEP method 3 is a special environment only suitable for the Ni-Mo alloys, as described below, in section 4. ISO iiso specifically for duplex and all jso stainless steels, and recommends ageing at two different temperatures: Why were these tests designed? ISO is the most rigorous in terms of defining test methods, and says which alloys should use which test methods as follows: ISO is the most rigorous in terms iiso defining test methods, and says which alloys should use which test methods as follows:.
The exception to this is ASTM G28 method A, where rates for the onset of intergranular corrosion are described in reference 1. ASTM G28 was designed for nickel-based alloys, and a list of applicable alloys for methods A and B is in the standard.
It has izo used for the duplex stainless steel UNS S iao, which has been is for nitric acid cooler tubes. Contact us by Phone or Email to find out how we can help your industry. 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. Some standards require the test sample to be aged prior to testing, to simulate the precipitation that might occur during welding.
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. For many alloys, the onset is at 0. 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 lso test method is difficult. Get in Touch Contact us by Phone or Email to find out how we can help your industry.
The most convenient size is often a cylinder 10mm diameter by mm long, but other dimensions are possible to suit particular product forms.
R Baboian, Corrosion Tests and Standards: The latter is a German test, but 351-2 is often called up in European projects. The test solutions and exposures for some common intergranular corrosion tests.
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.
SEP does not require ageing, although it might be required in a specification calling up this standard. The Tests Table 1 below shows the various methods for four common standards: There are a number of recognised tests when it comes to the intergranular corrosion testing of corrosion resistant alloys CRA.
Intergranular Corrosion Tests for CRAs
Both of these tests should be followed by water quenching. Where no specific test is specified, Table 5 suggests the most appropriate alongside a second choice, if the first is declined. Just remember that these tests were devised for specific groups of alloys and should not be applied to all CRAs! The effect of post weld surface treatments on the corrosion resistance of super duplex stainless steel welds in sea water None of these are identical and cross substitution of results is not possible.
This means that carbide formation during welding is highly unlikely, and modern CRAs should easily pass one of these tests. ISO is specifically for duplex and all austenitic stainless steels, and recommends ageing at two different temperatures:. It can be seen that some alloys fall into two categories, and no guidelines are given for selecting the most appropriate. 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.
Table 1 below shows the various methods for four common standards: 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.