Intergranular Attack (IGA) and its Importance

Better understanding on Intergranular Attack (IGA) 

IGA is most common in sensitized alloys, where the development of chromium carbides or other precipitates occurs at the grain boundaries. Sensitization can occur during manufacturing operations like welding, heat treatment, or an incorrect alloy composition. When a corrosive environment, such as specific chemical solutions or high-temperature conditions, is introduced into the alloy, the grain boundaries become sensitive to corrosion attack.

The fundamental process of intergranular assault is the dissolving or selective attack of grain boundary regions caused by the depletion of certain alloying elements, specifically chromium. The chromium-depleted zones are prone to corrosion, and this localised assault can spread along the grain boundaries, resulting in material degradation.

The fundamental process of intergranular assault is the dissolving or selective attack of grain boundary regions caused by the depletion of certain alloying elements, specifically chromium. The chromium-depleted zones are prone to corrosion, and this localised assault can spread along the grain boundaries, resulting in material degradation.

The intergranular attack can have serious effects since it might undermine the material’s structural integrity and mechanical qualities. In important applications, it can cause material weakening, intergranular cracking, or even catastrophic failure. Preventing or minimising IGA is therefore critical in businesses that rely on corrosion-resistant materials, such as chemical processing, oil and gas, and marine settings.

Different Approaches to Understand IGA 

Depending on the material and application, several methods can be implemented to prevent or minimise intergranular assault. Among the most common approaches are:

• Proper alloy selection entails selecting alloys with higher resistance to intergranular corrosion, such as low carbon grades or alloys with higher chromium content.
• Heat treatment: The use of heat treatments, such as solution annealing or sensitization treatments, to dissolve or eliminate precipitates and restore corrosion resistance to a material.
• Corrosion inhibitors: Using chemical inhibitors or protective coatings to protect the material from corrosive environments.
• Welding procedures, filler materials, and post-weld treatments should all be used to minimise sensitization and prevent an intergranular attack in welded joints.

It is important to note that the susceptibility to intergranular attack differs between alloys and conditions, and particular testing procedures, such as the ASTM G28 standard, can be used to assess material resistance to intergranular corrosion.

To ensure the long-term performance and dependability of metal components in corrosive environments, understanding and mitigating intergranular assault is critical in materials selection, design, and maintenance.