Coordinated deformation mechanisms of high formability Al-Mg-Si-Cu-Zn-Fe alloys via coupling control of thermomechanical processes

Both the high formability and strengths are greatly important for the automotive application of Al-Mg-Si-Cu alloys. In the present work, four novel thermomechanical processing routes were designed to improve the comprehensive properties of Al-Mg-Si-Cu-Zn-Fe alloys. The results show that, the interspace between Fe-rich particles and Fe/Mn-containing dispersoids can be significantly reduced by an optimized thermomechanical processing route. This enhanced the interaction between them during subsequent cold rolling process, resulting in increased number density and uniform distribution level of multi-scale Fe-rich particles, which further substantially improve both the recrystallization microstructure and mechanical properties, i.e., higher bendability, average r value of 0.72 (0.59 for traditional sheet) and tensile strength of 302 MPa (283 MPa for traditional sheet). The microstructure evolution of alloy sheets was schematically illustrated, and in-depth analysis on the mechanism of high formability was proceeded from the aspects of grain boundary misorientations and recrystallization texture.