Correlation of microstructure, texture and intermetallic particles during multi-step cross-rolling and annealing in a strip-cast AA8011 alloy

Abstract

In multi-step cross rolling (MSCR), twin roll cast (TRC)/strip-cast AA8011 aluminum sheet was cold-rolled up to 72 % thickness reduction by rotating +/- 90º with respect to normal direction (ND) after each rolling pass. The intermetallics particle size after MSCR got reduced to ∼ 0.5–3 µm compared to unidirectional cold rolling (UCR) ∼ 1.5 – 4.5 µm (Kumar et al. 2018) after the same thickness reduction of 72 %. Subsequently, it was annealed at 375 ºC for varying times (1–240 min). Both investigations (UCR/MSCR) showed no removal of centerline segregation (CLS) of Al-Fe-Si intermetallics. After 72 % cold rolling (UCR/MSCR), deformation texture (i.e., Brass (Bs) {110} < 112 > , copper (Cu) {112} < 111 > , Goss {110} < 011 > and S {123} < 634 > ) strengthened at the expense of Cube {100} < 001 > . However, cube improves during annealing at 375 ºC after MSCR than UCR. Moreover, it was observed that particle-stimulated nucleation (PSN) (intermetallics particle size ≥ 2 µm) played an important role in promoting random texture. For instance, the % volume fraction of Brass, Copper, Goss, S, Cube were 6.1 %, 5.3 %, 3.7 %, 9.0 %, 4.8 % (Kumar et al. 2018) and 6.5 %, 3.6 %, 1.9 %, 7.7 %, 5.3 % for UCR and MSCR, respectively. Hence, MSCR effectively reduces intermetallic particles size, decreases the overall anisotropy and improves the recrystallization texture (especially Cube component of texture) of TRC AA8011 aluminum alloy.