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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How do you select the right ASTM corrosion testing method for your material? ASTM does not give any aetm express or implied or make any representation that the contents of this abstract are accurate, complete or up to date. Each ASTM A Practice pracitce includes a list of the grades of stainless steels and the acceptable etch structures for the specific alloys. Practice E, the Strauss test, is performed to assess attack associated with chromium-rich carbide formation; it does not detect susceptibility to sigma phase formation.

This specification covers the standard practices for detecting susceptibility to intergranular attack in austenitic stainless steels.

If materials with incorrect heat treatment enter service, they are liable to crack or fail by intergranular corrosion IGC much more rapidly than asttm treated materials; ASTM A is a screening test to help find batches that are incorrectly processed.

The Oxalic Acid test is also only applicable to corrosion associated with chromium carbide precipitates and is only useful for specific material grades. Choosing an Intergranular Corrosion Test Method Since high temperature processing such as heat aztm 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.

Please specify the maximum allowable corrosion rate and any available data on the sensitizing heat treatment performed. A bend test practce by a visual or micro-examination are used to determine “Pass” or “Fail” of test specimens. To understand intergranular corrosion testing or intergranular attack commonly abbreviated as IGC or IGAit is important to understand what causes the process to occur.

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


Duplicate samples from both sides of a sheet sample are evaluated to determine if carburization results in intergranular attack. What is your typical turnaround time? Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard.

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 less oxidizing solutions.

The etch structure types used to classify the specimens are: However, when a material is exposed to high temperatures for long periods of time, a process called sensitization may occur. By using our website you consent to all cookies in accordance with our Cookie Policy. Intergranular corrosion shows up as the dark black lines around the grain boundaries.

ASTM A is a common intergranular corrosion testing method that can quickly screen batches of material to determine corrosion susceptibility. This abstract is a brief summary of the referenced standard. 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. A different ASTM A test method must be used to quantify the asfm of corrosion or to disqualify a material for use.

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. The samples are weighed at each interval to determine mass loss and degree of susceptibility to intergranular attack.

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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. Share on Tumblr Print. It is the responsibility of the user of this standard to establish appropriate safety a26 health practices and determine the applicability of regulatory limitations prior to use.


Practice B, also known as the Streicher test, uses weight loss analysis to provide a quantitative measure of the materials performance. The test pravtice the resistance of extra-low-carbon steels to sensitization and intergranular attack from welding or heat treatment processes. Please refer to the specification for more details. 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.

The chart below comes from the ASTM A standard for selection of the appropriate test by alloy type:.

ASTM A Testing: An Overview of Intergranular Corrosion | Element

All five methods within this specification involve exposing specimens to a chemical mixture designed to encourage corrosive behavior. The 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.

The weight loss is calculated after each step, and reveals if the sample has been properly heat-treated. These tests are often run as a qualification test to ensure each batch of stainless steel is properly prepared. 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.

If you are not sure, please contact us for assistance. Metals like stainless steels and aluminum contain elements such as niobium and chromium, often integrated because of their natural corrosion resistance. For example, many low-carbon and stabilized stainless steels e. These practices include five intergranular corrosion tests, namely: Classification of the structure after A Practice A analysis will determine if the material is acceptable or if additional testing is required.

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. Due to the variance of attack in different materials, numerous methods Practices B-F are used to assess intergranular corrosion.