Effects of Annealing Time on Microstructure and Properties of Al-Mg-Mn-Zr-Er Alloy Cold Rolled Sheet

The cold rolled Al-4.5Mg-0.7Mn-0.2Zr-0.2Er alloy sheet was prepared. After annealing at different recrystallization temperatures, the plates with different degrees of recrystallization were obtained. The mechanical properties and corrosion stability of the recrystallized sheet were tested and the microstructure of the alloy was analyzed by metallographic microscope, TEM and EBSD. The results show that, when the cold rolled alloy is annealed at 275 ℃for 45 min, the optimum match of mechanical properties and corrosion properties is obtained. With the increase of recrystallization degree, the original continuous grain boundary in cold rolled alloy is destroyed, and the β phase changes from continuous distribution along grain boundary to intermittent distribution, and the corrosion resistance of the alloy increases. The addition of Er and Zr in the alloy can form fine dispersed Al₃(Er, Zr) particles, which can block the migration of grain boundary, inhibit the recrystallization of the alloy and raise the recrystallization temperature.