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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It has been used for the duplex stainless steel UNS Swhich has been used for nitric acid cooler tubes.
The test methods in Table 1 were designed with specific alloys in mind, but the proliferation of new CRAs has uso that the selection of a suitable test method is difficult. Bend test criteria for several standards. The test solutions and exposures for some common intergranular corrosion tests. This test should be avoided for most CRAs, except in the circumstances described below, in section 4.
ISO is specifically for duplex and all austenitic stainless steels, and recommends ageing at two different temperatures: 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.
For alloys not listed in this standard, it will be necessary 36551-2 carry out some tests on material in various conditions to determine the threshold.
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.
The most convenient size is often a cylinder 10mm diameter by mm long, but other dimensions are possible to suit particular product forms. The Tests Table 1 below shows the various methods for four common standards: 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.
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. SEP also gives guidance on which of its methods apply to which alloys: Some suggested criteria for the listed alloys are shown in Table 2, below.
More suitable alternatives are offered in Table 5, below. All bend tests require a tensile test machine or similar, with suitable grips and sufficient strength to bend the strongest alloy. SEP method 3 is a special environment only suitable for the Ni-Mo alloys, as described below, in section 4.
The specifications for bend testing are shown in Table 4. Get in Touch Contact us by Phone or Email to find out how we can help your industry.
R Baboian, Corrosion Tests and Standards: Contact us by Phone or Email to find out how we can help your industry. SEP does not require ageing, although it might be required in a specification calling up this standard. The latter is a German test, but it is often called up in European projects.
This document describes all three of these tests for four common standards, and describes the differences. It does izo say what to do about duplex or super austenitic alloys. 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.
Alternatively, a welded test-piece in the as-welded condition may be tested. Table 1 below shows the various methods for four common standards: Both of these tests should be followed by water quenching. ASTM Ios lists alloys and specifies the test exposure for each.
The effect of post kso surface treatments on the corrosion resistance of super duplex stainless steel welds in sea water 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.
Some standards require the test oso to be aged prior to testing, to simulate the precipitation that might occur during welding.
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. There are a number of recognised tests when it comes to the intergranular corrosion testing of corrosion resistant alloys CRA. ASTM G28 is designed for nickel-based alloys, and a list of applicable alloys for methods A and B is in the standard.
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.
Intergranular Corrosion Tests for CRAs
ISO is the most rigorous in terms of defining test methods, and says which alloys should use which test methods as follows: 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:. Make an Enquiry Notice: Suggested test methods for different corrosion resistant alloys.
Where a standard is included in a purchase specification, this must be followed, ixo it is advised that unsuitable tests, such as the Huey test for duplex and super austenitic stainless steels, sio queried. ASTM G28 does not require samples to be heat treated. 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.
These tests were introduced when the carbon content in CRAs typically hit 0. The exception to this is ASTM G28 method A, where rates for the onset of intergranular corrosion are described in reference 1. ASTM A was designed for austenitic stainless steels, specifically the series alloys. Just remember that these tests were devised for specific groups of alloys and should not be applied to all CRAs!