Study on microstructure, mechanical properties and corrosion behavior of spray formed 7075 alloy

• After T6, UTS up to 760 MPa is obtained because the tiny MPt in matrix.
• For T73, discrete GBP and wide PFZ improved elongation, EXCO and IGC resistance.
• After RRA, UTS is up to 758 MPa and elongation and resistance are close to T73.
• After U–RRA–H, UTS is 791 MPa, elongation and resistance are close to RRA.

Microstructure and properties of the spray formed 7075 alloy with various heat treatments were studied by using tensile tester, transmission electron microscope and scanning electron microscope. The results show that the tiny precipitates distributed homogeneously in matrix can increase the ultimate tensile strength (UTS). The disconnected precipitates at grain boundary and wide precipitate free zones can improve the corrosion resistance of the alloy. Both strength and corrosion resistance of the alloy can be improved by retrogression and re-aging (RRA) processes. Especially, the U–RRA–H process can increase the UTS up to 791 MPa, which is higher than that after T6, T73 and conventional RRA treatments.