The Oxalic Acid test is only used to ensure that no corrosion exists; samples are labeled either "Acceptable" or "Suspect". A different ASTM A test method must be used to quantify the level of corrosion or to disqualify a material for use. The Oxalic Acid test is also only applicable to corrosion associated with chromium carbide precipitates and is only useful for specific material grades. Please refer to the specification for more details. The level of corrosion is determined by mass loss.
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If materials with incorrect heat treatment enter service, they are liable to crack or fail by intergranular corrosion IGC much more rapidly than properly treated materials; ASTM A is a screening test to help find batches that are incorrectly processed. Intergranular corrosion shows up as the dark black lines around the grain boundaries. We provide accurate, repeatable results along with world-class customer service.
We offer ASTM A testing from Houston for customers around the world; with overnight shipping, we can start immediately.
We work with you to select the right method for your steel grade, and then deliver clear results in a reasonable time and budget. How do you select the right ASTM corrosion testing method for your material? The first and fastest step is the ASTM A Practice A, a rapid same-day screening method in Oxalic acid to determine the susceptibility to intergranular corrosion. Classification of the structure after A Practice A analysis will determine if the material is acceptable or if additional testing is required.
If you are not sure, please contact us for assistance. Based on your materials, application, and requirements, the other 4 methods provide specific focuses. In everyday applications, corrosion varies by materials and solutions. For example, in highly oxidizing solutions, intergranular attack can occur due to intermetallic phases, while attack of carbides may occur somewhat less oxidizing solutions.
Due to the variance of attack in different materials, numerous methods Practices B-F are used to assess intergranular corrosion. 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.
For example, many low-carbon and stabilized stainless steels e. The test is generally performed for acceptance of materials, but not sufficient for rejection of materials. Because it can be run quickly for screening, we often run this test first. In SEM analysis, intergranular corrosion is clear by the dark lines where the grain boundaries are eaten away. This practice includes boiling the sample for 24 to hours in the solution above, and measures the materials performance quantitatively.
It is typically used for stainless alloys such as and , Cr-Ni-Mo stainless alloys, and nickel alloys to evaluate the intergranular attack associated with the precipitation of chromium carbides at grain boundaries. The weight loss is calculated after each step, and reveals if the sample has been properly heat-treated. Please specify the maximum allowable corrosion rate and any available data on the sensitizing heat treatment performed.
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. 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.
The test uses a visual inspection of the surface of the bent specimen to determine pass or fail. Duplicate samples from both sides of a sheet sample are evaluated to determine if carburization results in intergranular attack.
The bent samples are examined at low magnification, where the appearance of cracks or fissures indicate intergranular attack. The test evaluates the resistance of extra-low-carbon steels to sensitization and intergranular attack from welding or heat treatment processes. It depends on which Practice is selected, but typically ranges from to days for different tests. In many cases we can reduce that to as little as 24 hours more than the required testing time if you need fast results.
G2MT Labs is one of the few labs to offer all five ASTM A corrosion testing practices, as well as the expertise to help you determine which tests to use, what to do if a test fails, and other corrosion consulting as needed.
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Intergranular Corrosion Testing: An Overview of ASTM A262
If materials with incorrect heat treatment enter service, they are liable to crack or fail by intergranular corrosion IGC much more rapidly than properly treated materials; ASTM A is a screening test to help find batches that are incorrectly processed. Intergranular corrosion shows up as the dark black lines around the grain boundaries. We provide accurate, repeatable results along with world-class customer service. We offer ASTM A testing from Houston for customers around the world; with overnight shipping, we can start immediately. We work with you to select the right method for your steel grade, and then deliver clear results in a reasonable time and budget. How do you select the right ASTM corrosion testing method for your material? The first and fastest step is the ASTM A Practice A, a rapid same-day screening method in Oxalic acid to determine the susceptibility to intergranular corrosion.
To conduct these tests, w e carefully choose a method w hich is suitable for the steel grade and grain boundary composition to be tested. Intergranular corrosion in stainless steels may result from precipitation of carbides, nitrides or intermetallic phases. Only in the most highly oxidizing solutions can intergranular attack be caused by intermetallic phases. When a test is to be restricted to carbides, in a material containing nitrides or intermetallic phases, a less oxidizing solution is chosen. The test is used for acceptance but not rejection of material. This procedure measures the susceptibility of stainless steels and nickel alloys to inter granular attack associated w ith the precipitation of chromium carbides at grain boundaries.
Intergranular Corrosion (IGC) Testing Services
Intergranular corrosion refers to material degradation that occurs along the grain boundaries of metallic materials after exposure to a corrosive environment. The sustainability of certain stainless steels to IGC can be influenced by prior thermal processing and welding, which is referred to as sensitization. While the damage may not be immediately visible, intergranular corrosion can cause loss of strength and integrity in a material, resulting in defects or critical failures. With proven expertise in corrosion testing , failure analysis and material properties testing across industries, we are the partner of choice for your intergranular corrosion testing program. Intergranular Corrosion IGC testing We utilize different chemicals and test conditions to evaluate a range of metallic materials for intergranular corrosion, including stainless steel austenitic, duplex and ferritic grades , nickel alloys and aluminum alloys. Our Engaged Experts have years of experience working with metallic materials and can assist in choosing the most appropriate method for evaluating the intergranular corrosion resistance of your material.