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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However, there are necessarily limitations in the potential applicability of standard tests because the mechanism of corrosion in the service environment may be different than that targeted in the standard test, due to the difference between the actual service environment and the test solution.
ASTM G28 does not require samples to be heat treated. The specifications for bend testing are shown in Table 4.
Intergranular Attack Testing – ASTM G28 – Colorado-Metallurgical-Services
ASTM G28 was designed for nickel-based alloys, and a list of applicable alloys for methods A and B is in the standard. ISO is the most rigorous in terms of defining test methods, and says which alloys should use which test methods as follows:.
Advanced search Show search help. Nickel-rich, chromium-bearing alloys to intergranular corrosion may be g82 to intergranular corrosion, due to severe service conditions.
It is common practice to xstm intergranular corrosion testing in accordance with ASTM 1 G28 on solid solution nickel alloys, e. Bend test criteria for several standards.
Peer reviewed only Published between: 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 The Tests Table 1 below shows the various methods for four common standards: ISO is the most rigorous in terms of defining test methods, and says which alloys should use which test methods as follows: Proceedings of an international conference Oceanology: Therefore, the presence of grain boundary precipitation can be elucidated from the occurrence of intergranular corrosion in the test environments.
None of these are identical and cross substitution of results is not possible.
ASTM G28 test
SEP also gives guidance on which of its methods apply to which alloys: Method A requires to immerse the specimens in a ferric sulfate-sulfuric acid solution, while the solution described by Method B consists of mixed acid-oxidating salt including sulfuric astmm, hydrogen chloride, ferric chloride and copper chloride. SEP does asm require ageing, although it might be required in a specification calling up this standard. 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.
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. Suggested test methods for different corrosion resistant alloys.
Applicability of ASTM G28 Testing – OnePetro
There are a number of recognised tests when it comes to the intergranular corrosion testing of corrosion resistant alloys CRA. 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. Corrosion, caused by grain boundary precipitation phenomena, could be related to the chemical composition or the thermomechanical processing of the material.
It can be seen that some alloys fall into two categories, and no guidelines are given for selecting the most appropriate. This document describes all three of these tests for four common standards, ast describes the differences.