In aluminum alloy parts, intergranular corrosion:

In aluminum alloy parts, intergranular corrosion can often occur in a way that is not immediately visible on the surface. This type of corrosion happens along the grain boundaries of the metal, which may not produce any detectable surface indications such as pitting or discoloration that are common with other types of corrosion. Instead, it tends to affect the internal structure of the material, making it more insidious.

Detection of intergranular corrosion typically requires more sophisticated inspection methods, such as non-destructive testing techniques or microscopic examination, rather than relying solely on visual surface inspection. This characteristic highlights the importance of understanding the nature of intergranular corrosion, especially in critical components where integrity is essential.