Abstract: The mechanical properties of rolled sheets are not solely determined by their grain structure but also by their substructure. However, the features that constitute the substructure undergo significant changes throughout the production process, necessitating meticulous high-magnification and high-resolution analysis to properly characterize them. In this study, an in-depth investigation of the substructural evolution of a cold-rolled AAA3104 sheet during recovery and recrystallization thermal treatments was undertaken, with the aim of shedding light on its interplay with the resulting r values and subgrain boundary properties. It was observed that optimal formability behavior is exhibited by the partially recrystallized sample (H28), which is marked by the presence of roughly 14% subgrain angle boundaries featuring 2o–5o of misorientation, and comparable recrystallization and deformation texture components. This insight opens up new avenues for improving the formability and mechanical properties of rolled sheets by considering sub-structural engineering as a vital component of the production process. Thus, this study findings highlight that finely tuned substructural modifications could greatly enhance the mechanical properties of rolled sheets, thereby enabling both material scientists and engineers to better tailor these materials for specific applications in a variety of industries.