Influence of microstructure (Topic 11010)

Artificial ageing together with high amounts of Si or Cu will increase the susceptibility of intergranular corrosion. This is due to formation of cathodic and anodic areas on the grain boundaries because of precipitation in these areas.

If the cooling rate is too low, especially in the temperature range 400 to 300ƒC , the material may become susceptible to stress corrosion cracking (SCC) because of grain boundary precipitation. This can be more or less restored by artificial ageing. However, this may introduce possibilities for intergranular corrosion.

References [38]