Observing the alloy’s microstructural transformation changes during rolling deformation, from as-forged to 75 %, the formation process of multiscale structures was revealed. At 75 % deformation, a preliminary structure of large size αp phases (αp-L) + normal size αp phases (αp-N) formed. EBSD on the 75 % deformed sample proved αp-L results from joined α phases; αp-N emerged during rolling. After heat treatment, αs phases precipitated from β matrix, developing normal size αs phases (αs-N, aspect ratio 16.6) and short size αs phases (αs-S, aspect ratio 4.2), respectively corresponding to the distribution of αp-L and αp-N, respectively, creating the complete multiscale structure. This structure gives the alloy outstanding strength-ductility balance: 1460 MPa tensile strength, 8.7 % elongation, highlighting the importance of the multiscale structure for optimizing the alloy’s mechanical properties.