The influence of thermomechanical treatment on recrystallization of AlMg4.5Cu0.5 alloy

Abstract

Recrystallization behavior of an Al-Mg-Cu alloy (4.5 wt. %Mg and 0.45 wt %Cu) subjected to different thermomechanical treatments (TMTs) have been studied by means of light optical microscopy and hardness measurements. In order to provide controlled precipitation of Cu-Mg intermetallic particles two-stage annealing at 565°C/6h + 450°C/4h was applied. Then the tested alloy was cold rolled with 20, 40 and 60% reductions, and finally annealed for 3h at 250, 280 and 350°C, with slow and rapid heating rate (0.6 and 25°C/min). After annealing at 250°C/3h recovered grains were dominated in the structure. New recrystallized grains were revealed only in a few grains when r=40 and 60%. At 280°C a mixture of unrecrystallized and small new recrystallized grains (dav=20μm) was observed while after annealing at 350°C with high reductions a recrystallization process was completed. These observations were in agreement with hardness measurements. The heating rate was found also affecting the homogeneity of grain size distribution.