Dynamic precipitation and recrystallization in Al-12.5 wt%Si-0.6 wt%Mg-0.1 wt%Ti alloy during hot-rolling and their impacts on mechanical properties

Abstract

Dynamic precipitation and recrystallization behaviors in Al-12.5 wt%Si-0.6 wt%Mg-0.1 wt%Ti alloy during hot-rolling and their impacts on mechanical properties were investigated by microstructure characterization and tension test. The results show that higher temperature suppresses the dynamic precipitation of Mg2Si phase to a great extent, however, larger reduction ratio enhances this behavior. Phase distribution maps by EBSD strongly indicate that rolling above 500 °C leads to significant dynamic recrystallization. Increasing either the rolling temperature or reduction ratio favors dynamic recrystallization and refines the recrystallized grains. The reduction ratio has more distinguished effect than the temperature. Though dynamic recrystallization occurs remarkably, the deformation textures are dominant in the hot-rolled microstructure. Increasing either the temperature or reduction ratio make the texture intensity enhance. After rolling, the yield strength (YS) of all samples is improved compared with as-homogenized state except for the sample rolled at 500 °C with 33% reduction. At the same rolling reductions, the increment in strength by increasing the rolling temperature is resulted from the combination of diminished Mg2Si precipitation and refined recrystallized grains. At the same rolling temperatures, the increment in strength by increasing the rolling reduction is mainly attributed to the high intensity of deformation texture and high density of dislocations retained in recrystallized grains.