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 . 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. Intergranular Attack Susceptibility For Nickel Alloys.

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SEP method 3 is a special environment only suitable for the Ni-Mo alloys, as described below, in section 4. Both of these tests should be followed by water quenching. Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard.

Someone would have experience in this matter. ASTM A was designed for austenitic stainless steels, specifically the series alloys.

Technical Resources

In my f28 the samples shows damage only at six hours. Bend test criteria satm several standards. Sensitization or undesirable intergranular precipitation may occur due to deleterious thermal cycles, because of welding or heat treatment, for example.

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. This document describes all three of these tests for four common standards, and describes the differences.

It is possible to have grain boundary precipitation without the presence of chromium-depleted zones, and indeed such a microstructure has been shown to be beneficial in avoiding intergranular stress corrosion cracking IGSCC in high temperature water in nuclear industry applications, although clearly this cannot be generalized.


ISO is specifically for duplex and all austenitic stainless steels, and recommends ageing g2 two different temperatures:.

ISO is specifically for duplex and all austenitic stainless steels, and recommends ageing at two different temperatures: 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.

Contact us by Phone or Email to find out how we can help your industry. Hello everybody, My query is as follows: It does not say what to do about duplex or super austenitic alloys.

ASTM G28 test

There are a number of recognised tests when it comes to the intergranular corrosion testing of corrosion resistant alloys CRA. About us Contact us Help Terms of use.

Proceedings of an international conference Oceanology: Figure 1 shows a sensitized microstructure, where the darker etched grain boundaries have a decoration of precipitates. The Tests Table 1 asgm shows the various methods for four common standards: Alternatively, a welded test-piece in the as-welded condition may be tested.

Why were these tests designed?

Applicability of ASTM G28 Testing – OnePetro

The precipitation of such chromium-rich or molybdenum-rich particles often carbides usually also leads to regions depleted g8 Cr or Mo surrounding the precipitates. Hence, it is normally only used for stainless steels intended for nuclear service, or another application involving nitric acid.


These tests were introduced when the carbon content in CRAs typically hit 0. Incoloy will fail and not suitable for dilute sulfuric acid. SEP does not require ageing, although it might be required in a specification calling up this standard. The most convenient size is often a cylinder 10mm diameter by mm long, but other dimensions are possible to suit particular product forms.

Intergranular Attack Testing – ASTM G28 – Colorado-Metallurgical-Services

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 When migrating the old forums over to our new forums we were unable to retain the identity of the authors, so the old posts will show up as “anonymous”. R Baboian, Corrosion Tests and Standards: 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.

All NEW posts will show up credited to their authors. These regions will exhibit a lower resistance to the initiation of corrosion in the ASTM tests, and this is where the intergranular corrosion begins. Materials shown to be susceptible may or may not be intergranularly corroded in other environments.