What is ASTM A262 Intergranular Corrosion Test IGC

Intergranular corrosion is sometimes also called "intercrystalline corrosion" or "interdendritic corrosion". In the presence of tensile stress, cracking may occur along grain boundaries and this type of corrosion is frequently called "interranular stress corrosion cracking (IGSCC)" or simply "intergranular corrosion cracking".

Intergranular corrosion in stainless steel 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 following tests are carried out by us as per the ASTM A262 specification.

Oxalic Acid Test, ASTM A262, Practice A (Oxalic Acid Etch)

The oxalic acid etch test is a rapid method of screening those specimens of certain stainless steel grades which are essentially free of susceptibility to intergranular attack associated with chromium carbide participates. The test is used for acceptance but not rejection of material.

Ferric Sulfate - Sulfuric Acid, ASTM A262 - Practice B (Streicher Test)

This test is based on weight loss determinations and provides a quantitative measure of the relative performance of the material evaluated. The procedure includes subjecting a specimen to a 24 to 120 hour boil in ferric sulfate - 50% sulfuric acid. This procedure measures the susceptibility of stainless steel and nickel alloys to inter granular attack associated with the precipitation of chromium carbides at grain boundaries.

The specimens are boiled for five periods, each of 48 hours, in a 65 per cent solution of nitric acid. The corrosion rate during each boiling period is calculated from the decrease in the weight of the specimens. Properly interpreted, the results can reveal whether or not the steel has been heat-treated in the correct manner. The customer must specify the maximum permissible corrosion rate and, in applicable cases, data on sensibilizing heat treatment.

The Huey test environment is strongly oxidizing, and, is only used as a check on whether the material has been correctly heat treated. This test is suitable for the detection of chromium depleted regions as well as intermetallic precipitations, like sigma phase, in the material. The Huey test is also used for materials that come into contact with strongly oxidising agents, e.g. nitric acid. This procedure may also be used to check the effectiveness of stabilizing elements and of reductions in carbon content in reducing susceptibility to inter granular attack in chromium-nickel stainless steel.

Copper - Copper Sulfate - 50% sulfuric acid, ASTM A262 - Practice F
This test is based on weight loss determination which provides a quantitative measure of the relative performance of the material evaluated. It measures the susceptibility of "as received" stainless steels to inter granular attack.

Salt Spray (Neutral / Fog), ASTM B117

This is the most commonly used salt spray for testing of inorganic and organic coatings, especially where such tests are used for material or product specifications. Salt Spray testing is a tool for evaluation the uniformity of thickness and degree of porosity of metallic and nonmetallic protective coatings. A number of samples can be tested at once depending upon their size CASS Test, tarnishing test are also done.

Stainless Steel Tubes Intergranular Corrosion

Stainless Steel Tubes Intergranular Corrosion

Pitting Corrosion Test, ASTM Gr 48

This Procedure is used to assist in the selection of test methods that can be used in the identification and examination of pits and in the evaluation of pitting corrosion to determine the extent of its effect. The importance of this evaluation is to be able to determine the extent of pitting, either in a service application where it is necessary to predict the remaining life in a metal structure, or in laboratory test programs that are used to select the most pitting-resistant materials for service. ASTM Gr 48 Method A and ASTM A923 Method C are typical pitting corrosion tests performed.

Hydrogen-Induced Cracking (HIC) Test, NACE TMO284

This test method evaluates the resistance of pipeline and pressure vessel plate steels to Hydrogen Inducted Cracking caused by hydrogen absorption from aqueous sulfide corrosion. An unstressed test specimen is exposed to a solution at ambient temperature and pressure and after a specified time, the test specimen is removed and evaluated.

Sulfide Stress Corrosion Cracking (SSCC), NACE TM 0177

The polythionic acid (sulfurous acid and hydrogen sulfide) environment provides a way of evaluating the resistance of stainless steels and related alloys to inter-granular stress corrosion cracking. This practice can be applied to wrought products, castings, weld metal of stainless steels or other materials to be used in environments containing sulfur or sulfides

Chloride Stress Corrosion Test as per ASTM Gr 36 Specification

Stainless Steel Tubes Intergranular Corrosion