Promotion of texture weakening in magnesium by alloying and thermomechanical processing. II: rolling speed

摘要

In the first part of this two-part paper, the effect of increasing Ce in solid solution on the recrystallization and texture evolution of four Mg–Zn–Ce sheets was investigated in the as-deformed and annealed state. In this second part, the effect of rolling speed on the microstructure and texture development of these alloys is evaluated. The effect of rolling speed on the recrystallization and texture evolution of four Mg–Zn–Ce sheets was investigated at as-deformed and different stages of annealing. The deformation microstructure was obtained through two stages that can be characterised as rough rolling and finish rolling. To study the effect of finish rolling temperature, one rolling pass with a 65 % reduction in thickness was performed at 300 and 450 ℃ and at rolling speeds of 15 and 1000 m/min. The results showed that by increasing the rolling speed, more secondary and compression twins were activated, which leads to the formation of more numerous local shear bands and a more uniform microstructure. Annealing secondary twins (S-twins) and their vicinity were observed to be the preferential sites for nucleation, and it seems that recrystallization on S-twins contributes to basal texture weakening. Therefore, an increasing number of such twins increase the texture weakening. In this way, the combination of these RE additions and HSR resulted in a weaker deformed and annealed texture.