Effect of secondary α-phase precipitation on high-strain-rate deformation and shear band evolution in metastable β-titanium alloy

This work characterizes the dynamic response and failure evolution in a metastable β-Ti alloy under high-strain-rate deformation. Two microstructural states were prepared: annealing (ANN) and solution treatment plus aging (STA). The effects of secondary α-phase (α s ) precipitation and dynamic recrystallization (DRX) on mechanical properties were systematically analyzed for the STA and ANN specimens. Results indicated that the STA specimen exhibited higher yield strength (YS) and ultimate tensile strength (UTS) than the ANN specimen. However, this strength enhancement was accompanied by a 32.5% reduction in ductility and a 43.3% decline in impact toughness. Under high-strain-rate deformation, the STA specimen demonstrated higher flow stress and exhibited greater plastic strain. These improvements in dynamic performance are attributed to the precipitation of α s phase along grain boundaries, which stabilizes the microstructure and delays the onset of shear localization. In contrast, the ANN specimen, which undergoes limited dynamic recrystallization and phase transformation, exhibits more severe strain localization compared to the STA specimen. Consequently, strain localization triggers crack nucleation and propagation within adiabatic shear band (ASB) regions. These microstructural and mechanical differences underscore the critical importance of microstructural control and highlight the essential role of secondary α s phase precipitation and dynamic recrystallization (DRX) in enhancing the dynamic performance of titanium alloys.