5 Jul Alloy 22 is a Ni-Cr-Mo alloy (Nickel-Chromium-Molybdenum) and is one of the most versatile corrosion resistant alloys used in industry today. ABSTRACT It is common practice to perform intergranular corrosion testing in accordance with ASTM (1) G28 on solid solution nickel alloys, e.g. UNS N . 13 Apr ASTM G – Designation: G 28 – 02 Standard Test Methods of Detecting Susceptibility to Inter.

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Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not asm as part of the standard. Warning statements are given in 5. Proceedings of an international conference Subsea Controls and Data Acquisition ‘ ISO is specifically for duplex and all austenitic stainless steels, and recommends ageing at two different temperatures: ISO is the most rigorous in terms of defining test methods, and says which alloys should use which test methods as follows: Alternatively, astmm welded test-piece in ashm as-welded condition may be tested.

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. All bend tests require a tensile test machine or similar, with suitable grips and sufficient strength to bend the strongest alloy.

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About us Contact us Help Terms of use. Peer reviewed only Published between: R Baboian, Corrosion Tests and Standards: 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. However, the ASTM standards acknowledge that the environments that the material will experience in service are likely to differ from those of the test methods, in which case the corrosion performance could be different.


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Why were these tests designed? Where no specific test is g82, Table 5 suggests the most appropriate alongside a second choice, if the first is declined. 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.

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. Advanced search Show search help.

These environments are typically oxidizing and acidic e. There are a number of recognised tests when it comes to the intergranular corrosion testing of corrosion resistant alloys CRA. The susceptibility to intergranular corrosion in wrought, nickel-rich and chromium-bearing alloys can be detected by measuring the mass loss of the test pieces.

Make an Enquiry Notice: The Tests Table 1 below shows the various methods aastm four common standards: The ASTM G28 test methods A and B are utilized in many industries as quality control tests in order to assess the resistance to intergranular corrosion of various stainless steels and nickel-based alloys, such as Alloy and Alloy It does not say what to do about duplex or super austenitic alloys.

Asm B and E are suggested for all grades of series austenitic alloys, while method F is suggested for cast type alloys.

Link to Active This link will always route to the current Active version of the standard. ASTM G28 does not require samples to be awtm treated.

Corrosion Materials – ASTM G28 test

The test method is not applicable to cast products. The specifications for bend testing are shown in Table 4. JavaScript is required for this content. Some standards require the test sample to be aged prior to testing, to simulate the precipitation that might occur during welding. The most convenient size is often a cylinder 10mm diameter by mm long, but other dimensions are possible to suit particular product forms.


Resistance to Intergranular Corrosion of Nickel Rich Chromium Bearing Alloys

The exception to this is ASTM G28 method A, where rates for the onset of intergranular corrosion are described in reference 1. Some suggested criteria for astn listed alloys are zstm in Table asrm, below. The uniform corrosion rate obtained by this test method, which is a function of minor variations in alloy composition, may easily mask the intergranular corrosion components of the overall corrosion rate on alloys N, N, N, and N SEP method 3 is a special environment only suitable for the Ni-Mo alloys, as described below, in section 4.

Figure 1 shows a sensitized microstructure, where the darker etched grain boundaries have a decoration of precipitates.

Both of these tests should be followed by water quenching. Good material should have a corrosion rate substantially less than the threshold value.

It can be seen that some alloys fall into two categories, and no guidelines are given for selecting the most appropriate. Nickel-rich, chromium-bearing alloys to intergranular corrosion may be subjected to intergranular corrosion, due to severe service conditions.

For many alloys, the onset is at 0. Wstm 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 satm a microsection in any suspicious areas. These tests were introduced when the carbon content in CRAs typically hit 0.