Retrogression on corrosion behavior of spray formed Al-7075

The effects of retrogression and re-aging (RRA) treatment on intergranular corrosion (IGC), exfoliation corrosion (EXCO), stress corrosion cracking (SCC) behavior and microstructure of spray formed Al-7075 were investigated by a scanning electron microscope, a transmission electron microscope, slow strain rate test, and EXCO and IGC test. The results show that the precipitates are redissolved in the matrix of the alloy after retrogression at 200 °C for a suitable time (8 min), and the grain boundary precipitates are discrete and the obvious precipitate free zones are left at the grain boundaries. After RRA with suitable retrogressed time, thin homogeneous dispersive precipitates are separated out again in the matrix. After retrogression at 200 °C for 8 min and re-aging, the ultimate tensile strength, elongation, IGC depth, EXCO rating, and SCC index of spray formed Al-7075 are 791 MPa, 8.5%, 29.8 μm, EA, and 0.155, respectively.