Microstructure evolution of different loading zones during TA15 alloy multi-cycle isothermal local forging

► Microstructure of different loading zones in TA15 multi-cycle local near-β forging. ► A small equiaxial microstructure in first loading zone with more α-phase. ► A tri-modal microstructure in second loading zone with good mechanical property. ► Microstructure in TA15 multi-cycle conventional forging + near-β heat treatment. ► Large bimodal microstructures in both loading zones with poor mechanical property.