Microstructural studies on the effect of Si and Cr on the intergranular corrosion in Al---Mg---Si alloys

Microstructural studies on the effect of Si and Cr on the intergranular corrosion of two Al---Mg---Si alloys have been carried out as a function of aging treatment. It was observed that the degree of intergranular attack increases with increasing aging time with a maximum at peak aged condition and then declines. Presence of Si in the alloy has a tendency to segregate at the grain boundary which makes the alloy susceptible to intergranular corrosion. Addition of a small amount of Cr in the alloy improves the resistance to intergranular corrosion.