Recrystallization behavior of high-strength AA 7075 alloy processed by new short-cycled thermo-mechanical processing

摘要

Recrystallization behavior under different conditions (different temperatures and times) of AA 7075 alloy processed by new short-cycled thermo-mechanical processing was investigated to design a suitable recrystallization schedule. With acquiring recrystallization activation energy by DSC, the recrystallization behavior was successfully verified by theoretical calculation. Experimental results of recrystallization response and re-dissolution of precipitates during isothermal annealing reveal excellent agreement with DSC prediction. The results show that the obtained activation energy of recrystallization can be used to establish the relationship between recrystallization temperatures and times. It is proposed that an appropriate recrystallization treatment (703-753 K/1-5 min) could be used to acquire completely recrystallized grains with size ＜ 10 μm, contributing to better formability/ductility. The coarsening rate of these fine recrystallized grains is fairly low even though extending the solution treatment times at 753 K. Therefore, it indicates that the recrystallization dynamical equation would be a useful method to adjust recrystallization temperatures and times to satisfy various requirements of structures and properties.