The quenching sensitivity of high zinc-containing Al-Zn-Mg-Cu alloy was described under different heat treatment conditions.The results show that the hardness retention values of the high zinc-containing Al-Zn-MgCu alloy with end quenching at 120 mm are 91.26% and 96.25% after artificial aging and natural aging

respectively.With the increase of the distance from the quenched end of the specimen after artificial aging

the size of the precipitation-enhancing phase is increased with the decrease of the density

and the non-deposited precipitation band becomes wider

all of which reduce its hardness.The GP zone is the main strengthening phase of the natural aging alloy

and the density difference between the quenched end and the quenched end of the specimen is relatively low after natural aging for 1 680 h

therefore

the high zinc-containing Al-Zn-Mg-Cu alloy in this state has low quenching sensitivity.