Microstructure evolution of 7050 aluminum forgings during surface cumulative plastic deformation

Abstract

To elucidate the mechanisms of regulating the microstructure uniformity in 7050 aluminum forgings through surface cumulative plastic deformation (SCPD), the microstructure under different solution treatments was investigated using metallographic observation (OM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The findings demonstrate that the most uniform microstructure in the forgings is achieved with a solution treatment at 470 °C for 30 min. The SCPD process generates a significant number of needle-shaped precipitates, resulting in a higher dislocation density and stored energy. Solution treatments alleviate the pinning effect of second-phase particles and facilitate static recrystallization (SRX) in forgings, leading to a reduction in grain size. Additionally, mechanical testing results demonstrate 7%−13% increase in tensile strength and more uniform elongation of the forgings in different directions.