Effect of solution treatment process on microstructure and properties of 7175 aluminum alloy was investigated through tensile property testing,hardness testing,optical microscope(OM),scanning electron microscope(SEM)and transmission electron microscope(TEM).The results show that when the 7175 aluminum alloy is solution treated at 485 ℃ for 3.5 h,the second phase contont gradually decreases,and there is a tendency for grain coarsening.When the 7175 aluminum alloy is solution treated at 475 ℃ for 2.5 h,MgZn2 phase will rely on the Cr containing phase to nucleate at the grain boundary,playing a role in pinning the grain boundary and inhibiting grain growth.At the same time,with the increase of solution temperature and time,the tensile strength and microhardness of the alloy after aging at 120 ℃ for 12 h and 165 ℃ for 5.5 h show a trend of first increasing and then decreasing.When the solution treatment process is 475 ℃ ×2.5 h,the tensile strength is 631.2 MPa,the yield strength is 555.7 MPa and the elongation is 12.5％,with the optimal comprehensive mechanical properties.
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