Achieving superior ductility and toughening in as-cast 2055 Al–Li alloy through single-pass rolling with a small reduction ratio for homogenization

Single/double-step conventional homogenization and pre-rolling homogenization treatments were employed to solve the problems of severe dendritic segregation of as-cast 2055 Al-Li alloy, large grain size and grain boundary overburning caused by conventional high-temperature long-term homogenization. The results indicate that single-pass rolling with a small reduction ratio can introduce defects such as vacancies and dislocations, providing conditions for the full, rapid and uniform diffusion of alloying elements. At 470°C/2h + FR27.5% (Flat Rolling, reduction ratio is 27.5%) + 520°C/8h, the dendritic segregation of as-cast alloy is effectively eliminated in a short time, showing high tensile strength and plasticity, which can reach 352 MPa and 11.4% respectively. Compared with the conventional homogenization treatments, the average grain size decreases from 78.45 μm to 36.47 μm, and the volume fraction of secondary phase reaches a minimum of 0.33%. The results of diffusion kinetics analysis also indicate that the deformation promotes diffusion and further shortens the homogenization time, which is consistent with the microstructural results. Therefore, 470°C/2 h+FR27.5% + 520°C/8 h is determined as optimal homogenization system. This work provides a new idea for the high-temperature short-term homogenization treatment of as-cast 2055 Al-Li alloy.