Abstract
Laser powder bed fused (LPBF) near-beta Ti-5Al-5Mo-5V-3Cr (Ti-5553) titanium alloy offers an attractive combination of high strength and heat-treatability. However, capturing the evolution of deformation stability under coupled high strain-rate and thermal loading remains a central challenge for additively manufactured metastable Ti-5553 alloy. Given the critical role of adiabatic shear band (ASB) formation in governing plastic instability and failure under impact loading, this study focuses on identifying temperature-dependent deformation pathways and the onset of localization under near-adiabatic conditions. High-temperature dynamic compression experiments revealed that localized shear progressively dominates the deformation response with increasing temperature, accompanied by enhanced recovery activity and pronounced grain shape evolution outside the shear zones. Under the most extreme combination of high strain rate and elevated temperature, well-defined adiabatic shear bands formed and were characterized by fully recrystallized ultrafine equiaxed microstructures, indicating severe localized strain and temperature rise. In contrast, regions remote from the shear bands exhibited extensive grain pancaking together with partial recrystallization, reflecting bulk thermal softening rather than localized instability. Micro-texture analysis further revealed the rotation of β grains away from the LPBF-inherited ⟨100⟩ texture toward alternative preferred orientations under dynamic loading. Together, these observations provide a framework for understanding how thermal conditions govern deformation localization in LPBF-made Ti-5553 and offer experimentally grounded insight into the mechanisms controlling impact-induced failure in additively manufactured β-titanium alloys.