Evolution of microstructure, texture and formability of Al–Mg–Si alloys at different hot rolling finish temperatures

Abstract

The impact of hot rolling finish temperature (HRFT) on the evolution of microstructure, texture, as well as formability—including deep drawability and bendability—of Al–Mg–Si alloy was studied in present work. The obtained results reveal that HRFT has a notable influence on the dynamic softening and dynamic precipitation behaviors during the hot rolling process of the investigated alloy. This leads to the volume fraction and number density of micro-sized Mg2Si particles increase as the increase of HRFT, those of nano-sized particles decrease, and the dislocation density decrease, in the hot-rolled sheets. These microstructural variations persist in the cold-rolled sheets, subsequently affecting the ultimate microstructure, texture, as well as formability of T4P sheets. The deep drawability improves as the HRFT rises, as indicated by the increase in normal anisotropy (r‾) and decrease in planar anisotropy (Δr). This is attributed to the weakening of texture intensity. The bendability, quantified by the minimum hemming factor (Rmin/t), deteriorates as the HRFT rises from 260 °C to 390 °C, attributed to the strengthening of P component along with the weakening of Cube component. Conversely, with the HRFT rises from 390 °C to 420 °C, the bendability improves dramatically due to the significant reduction in the average grain size. A combination of excellent deep drawability and bendability could be obtained by elevating the HRFT to 420 °C, attributed to the combined effect of weakened texture intensity and fine grains.