The corrosion behaviors of Al-7Si cast alloys in 3.5% NaCl aqueous solution were examined by using electrochemical corrosion and immersion corrosion tests.Influence of manganese（Mn）and tin（Sn）on the Tafel curves and electrochemical parameters

such as free corrosion potential and corrosion current densities

of Al-7Si alloys were investigated.Moreover

the weight loss and morphology of the alloys after immersion corrosion were measured and analyzed by analytical balance and scanning electron microscopy（SEM）.The results indicate that all the tested alloys can be passivated rapidly

and their corrosion potential is drifted to negative

meanwhile

their corrosion current density and corrosion weight loss are increased with the addition of alloy elements Mn and Sn

greatly deteriorating the corrosion resistance of the alloy.In addition

the corrosion morphology and corrosion mechanism of Al-7Si cast alloys were described.