The primary purpose of intergranular testing is to detect adverse changes that can occur within the internal structure of a material and assess how these changes affect the material's performance. Intergranular corrosion refers to the corrosion or chemical deterioration process that takes place at the interfaces between the particles of the material. This type of corrosion can reduce the material's durability and lead to cracking or wear over time.

Intergranular testing may be performed for the following reasons:

1. Corrosion Assessment: The greater the susceptibility or resistance of a material to corrosion, the higher the risk of intergranular corrosion within its internal structure. Therefore, this test can be conducted to evaluate corrosion resistance based on the environmental conditions in which the material is used.

2. Quality Control: Monitoring and controlling the quality of materials in the manufacturing processes is crucial. Intergranular testing can be used to detect problems in the internal structure of the manufactured material and improve product quality.

3. Material Selection: Material engineers can consider the results of intergranular testing when selecting the most suitable material for a specific application. This can assist them in predicting the long-term performance and durability of the material.

Intergranular tests can be conducted using different methods and standards. For example, sensitization tests or electrochemical tests are some of the common methods used to assess intergranular corrosion. These tests play an important role in identifying changes within the material's internal structure and preventing potential issues.