Intergranular Corrosion Test (IGC) per ASTM A At TCR Engineering Services, several methods exist for the testing of intergranular corrosion. To conduct. Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels. ASTM A is the specification which governs five practices used to determine if the. Abstract. A detailed study of AISI and stainless steels (SSs) has been conducted to correlate the degree of sensitization (DOS) measured by the.

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Intergranular Corrosion Tests for CRAs

If you are not sure, please contact us for assistance. Classification of structure then provides either acceptance or further testing required, which typically moves you to one of the next practices. Typical examination magnification is X to X. Like what you saw? The latter is a German test, but it is often called up in European projects. The samples are weighed at each interval to determine mass loss and degree of susceptibility to intergranular attack.

If the structure is acceptable no additional testing is required.

Intergranular Attack – ASTM A – Colorado-Metallurgical-Services

R Baboian, Corrosion Tests and Standards: This practice includes boiling the sample for 24 to hours in the solution above, and measures the materials performance quantitatively.

Wilson Hardness Conversion Chart. Work Item s – proposed revisions of this standard. For example, in highly oxidizing solutions, intergranular attack can occur due to intermetallic phases, while attack of carbides may occur somewhat satm oxidizing solutions. Please share this page: Methods for preparing a26 test specimens, rapid screening tests, apparatus setup and testing procedures, and calculations and report contents are described for each testing practice.

This method is a hour boiling test for “as received” specimens of stainless steel. 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.

The samples are etched after metallographic preparation for cross-sectional examination which is thoroughly viewed with a traverse from inside to outside diameters of rods and tubes, from face to face on plates, and across all zones such as weld metal, weld-affected zones, and base plates on specimens containing welds. There are a number of recognised tests when it comes to the intergranular corrosion testing of corrosion resistant alloys CRA.


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All austenitic stainless steels should meet this requirement, if proper annealing took place. Table 1 below shows the various methods for four common standards: Just remember that these tests were devised for specific groups of alloys and should not be applied to all CRAs!

It depends on which Practice is selected, but typically ranges from to days for different tests. Our knowledgeable scientists have the experience and expertise necessary to determine the most appropriate intergranular attack testing methods for your material while providing actionable results you can rely on.

See Appendix X1 asstm information regarding test selection. All five methods within this specification involve exposing specimens to a chemical mixture a226 to encourage corrosive behavior. The most convenient size is often a a2662 10mm diameter by mm long, but other dimensions are possible to suit particular product forms. Intergranular corrosion occurs as a result of precipitation of nitrides a2662, carbidesand other intermetallic phasessuch as sigma phase, that occurs along the grain boundaries.

Historical Version s – view previous versions of standard. The chart below aa262 from the ASTM A standard for selection of the appropriate test by alloy type:. 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.

Methods B and E are suggested for all grades of series austenitic alloys, while method F is suggested for cast type alloys. The oxalic acid test is commonly used before the Strauss test to determine if a sample is susceptible; samples that pass method A will generally show low corrosion rates in the Strauss test.

This abstract is a brief summary of the referenced standard. 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.

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Intergranular simply means that the corrosion is taking place between the grains or crystals, which is where sigma phase or chromium carbides are going to form which makes the material susceptible to IGA. The test uses a visual inspection of the surface of the bent specimen to determine pass or fail.


These practices include five intergranular corrosion tests, namely: 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.

For example, many low-carbon and stabilized stainless steels e. We provide intergranular corrosion evaluation, salt spray testing, stress corrosion, and various other methods to simulate exposure of your products or materials to corrosive environments.

SEP method 3 is a special environment only suitable for the Ni-Mo alloys, as described below, in section 4. This method is preferable for chromium depletions and corrosion in intermetallic phases. Please specify the maximum allowable corrosion rate and any available data on the sensitizing heat treatment performed.

This means that carbide formation during welding is highly unlikely, and modern CRAs should easily pass one of these tests. The test is generally performed for acceptance of materials, but not sufficient for rejection of materials. The Oxalic Acid test is only used to ensure that no corrosion exists; samples are labeled either “Acceptable” or “Suspect”. The inch-pound equivalents are in parentheses and may be approximate.

Intergranular Corrosion Testing: An Overview of ASTM A262

This specification covers the standard practices for detecting susceptibility to intergranular attack in austenitic stainless steels. How do you select the right ASTM corrosion testing method for your material? ASTM G28 lists alloys and specifies the test exposure for each. Carbon and Sulfur Analysis. The Huey test works well to analyze chromium depleted regions and intermetallic precipitates, such as sigma phase, and is also used for materials in strongly oxidizing environments such as nitric acid.

This specification is for detecting astn to intergranular attack IGA.