Effect of Zener-Hollomon parameter on quench sensitivity of 7085 aluminum alloy

The effect of Zener-Hollomon (Z) parameter on quench sensitivity of 7085 aluminum alloy was investigated. With the increase of Z parameter from 2.67E10 to 4.79E16, quench sensitivity relative to hardness tends to decrease first and then increase, and it may be minimised in the range from 2.67E12 to 2.24E13. The reason was discussed mainly on the effect of Z parameter on recrystallization fraction, which changes the amount of nucleation sites of heterogeneous precipitation during slow quenching. Quench-induced η phase with little strengthening effect tends to form preferentially at grain boundaries and on the Al3Zr dispersoids with a size larger than about 23 nm in the recrystallized grains. The increase in the number of recrystallized grains can increase the amount of such grain boundaries and Al3Zr dispersoids, and therefore a larger amount of quench-induced phase; consequently, quench sensitivity increases.