Ti6321(Ti-6Al-3Nb-2Cr-1Mo) alloys are widely employed in ships and marine engineering equipment. However, the complex microstructural evolution mechanisms of this alloy during hot deformation present significant challenges for integrated forming and performance-oriented manufacturing. A comprehensive understanding of its flow behavior and deformation mechanisms is essential to provide theoretical guidance for the manufacturing of Ti6321 alloy structural components that satisfy both the forming quality and microstructural performance requirements under complex hot deformation conditions. To clarify the dynamic softening mechanisms of the Ti6321 titanium alloy during hot deformation, isothermal hot compression tests were performed, combined with SEM and EBSD analyses. The flow behavior and microstructural evolution in the α+β phase region (850~950 ℃)were systematically investigated. The results indicate that the flow curves of the alloy display typical alternating work hardening and dynamic softening characteristics. The peak stress increases significantly with decreasing temperature or increasing strain rate. The dynamic recrystallization mechanism

is dominated by discontinuous dynamic recrystallization, characterized by grain nucleation along deformed grain boundaries to form “necklace-like” structures, whereas continuous dynamic recrystallization through subgrain rotation and coalescence makes a relatively minor contribution to flow softening. Higher deformation temperatures promote β phase formation, suppress dynamic recrystallization, and result in grain coarsening. Furthermore, the distribution of grain boundary misorientation angles and phase reconstruction analysis at elevated temperatures confirmes the occurrence of dynamic phase transformation. Finally, the coupled softening mechanisms of dynamic recrystallization and dynamic phase transformation during the hot deformation of the Ti6321 alloy are elucidated.