Nitric Acid, ASTM A, Practice C, (Huey Test) The specimens are boiled for five periods, each of 48 hours, in a 65 per cent solution of nitric acid. The corrosion. employed to measure the relative susceptibility of austenitic stainless steels to intergranular attack. ASTM A Practice C, boiling nitric acid test is also known . Ferric Sulfate – Sulfuric Acid, ASTM A – Practice B (Stretcher Test). Ferric Sulfate Nitric Acid, ASTM A, Practice C, (Huey Test). Nitric Acid, ASTM A

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Due to the variance of attack in different materials, numerous methods Practices B-F are used to assess intergranular corrosion. In many cases we can reduce that to as little as 24 hours more than the required testing time if you need fast results.

ASTM A Testing: An Overview of Intergranular Corrosion | Element

Intergranular corrosion occurs as a result of precipitation of nitridescarbidesand other intermetallic phasessuch as sigma phase, that occurs along the grain boundaries. How do you select the right ASTM corrosion testing method for your material? The Oxalic Acid test is only used to ensure that pradtice corrosion exists; samples are labeled either “Acceptable” or “Suspect”.

These tests do not provide a basis for predicting resistance to forms of corrosion other than intergranular, such as general corrosion, pitting, or stress-corrosion prractice. A recent publication on intergranular corrosion.

It is informational only and not an official part of the standard; the full text of the standard itself must be referred to for its use and application. ASTM A ptactice a common intergranular corrosion testing method that can quickly screen batches of material to determine corrosion susceptibility. All five methods within this specification involve exposing specimens to a chemical mixture designed to encourage corrosive behavior.

Corrosion Testing

Choosing an Intergranular Corrosion Test Method Since high temperature processing such as heat treatment is a common practice, many manufacturers wish to perform intergranular corrosion qualification testing on each batch, to ensure that the material has been processed correctly and does not show signs of corrosion susceptibility.

The test is generally performed for acceptance of practife, but not sufficient for rejection of materials. A different ASTM A test method must be used to quantify the level of corrosion or to disqualify a material for use.


View more articles about Aerospace Oil and Gas Transportation. The first and fastest step is the ASTM A Practice A, a pdactice same-day screening method in Oxalic acid to determine the susceptibility to intergranular corrosion. For example, many low-carbon and stabilized stainless steels e.

In SEM analysis, intergranular corrosion is clear by the dark lines where the grain boundaries are eaten away. This test is used exclusively to determine corrosion in areas high in chromium carbide formations, and is not as effective for intergranular attack caused by other means.

Oractice abstract is a brief summary of the referenced standard. However, when a material is exposed to high temperatures for long periods of time, a process called sensitization may occur.

Learn more about our laboratories – where they are located; the unique capabilities they have and how they can help you solve your technical and commercial challenges. Duplicate samples from both sides of a sheet sample are evaluated to determine if carburization results in intergranular attack. Sensitization causes the grain boundaries of a material to precipitate, creating carbide deposits and causing the material to be susceptible to intergranular attack.

This method is a hour boiling test for “as received” specimens of stainless steel. If you are not sure, please contact us for assistance. Please refer to the specification for more details.

Contact us now for pricing or a quote! The inch-pound equivalents are in parentheses and may be approximate.

This method is preferable for chromium depletions and corrosion in intermetallic phases. The weight loss is calculated after each step, and reveals if the sample has been properly heat-treated.

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Metals like stainless steels and aluminum contain elements such wstm niobium and chromium, often integrated because of their natural corrosion resistance. The Oxalic Acid test is also only applicable to corrosion associated with chromium carbide precipitates and is only useful for specific material grades.

Aastm ASTM A tests can determine if the proper heat treatment was performed or if the alloys are in danger of intergranular corrosion occurring in use. This website uses cookies to improve user experience.

Testing Services

What is your typical turnaround time? Practice F, is a hour weight-loss based practic that provides a quantitative measure of the materials performance, and is commonly used to analyze as-received stainless steels. The oxalic acid xstm 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.


It is typically used for stainless alloys such as andCr-Ni-Mo stainless alloys, and nickel alloys to evaluate the intergranular attack associated with the precipitation of chromium carbides at grain boundaries. This practice includes boiling the sample for 24 to hours in the solution above, and measures the materials performance quantitatively.

A bend test followed by a visual or micro-examination are used to determine “Pass” or “Fail” of test specimens. The test uses a visual inspection of the surface of the bent specimen to determine pass or fail. Share on Tumblr Print. Because it can be run a62 for screening, we often run this test first.

Discover perspectives, resources, and advice from our world-leading Engaged Experts. The chart below comes from the ASTM A standard for selection of the appropriate test by alloy type:. The Strauss test is commonly used to evaluate the heat-treatment of as-received material, the effectiveness of alloying additions of elements such as Nb and Ti, or the effectiveness of reducing carbon content to resist intergranular attack.

Classification of the structure after A Practice A analysis will determine if the material is acceptable or if additional testing is required. For example, in highly oxidizing solutions, intergranular attack can occur due to intermetallic phases, while attack of carbides may occur somewhat less oxidizing solutions.

This simple etching technique is used as a quick screening method to ensure that a material is free of intergranular corrosion susceptibility. These tests are often run as a qualification test to ensure each batch of stainless steel is properly prepared. Each ASTM A Practice specification includes a list of the grades of stainless steels and the acceptable etch structures for the specific alloys.

Methods for preparing the test specimens, rapid screening tests, apparatus setup and testing procedures, and calculations and report contents are described for each testing practice.

These practices include five intergranular corrosion tests, namely: Since high temperature processing such as heat treatment is a common practice, many manufacturers wish to perform intergranular corrosion qualification testing on each batch, to ensure that the material has been processed correctly and does not show signs of corrosion susceptibility.