Dynamic recrystallization and deformation mechanism of Ti6Al4V-0.55Fe alloy under different compression modes

Isothermal single-pass and non-isothermal multi-pass hot compression tests were conducted on Ti-6Al-4V-0.55Fe alloy at 890–990°C and 0.01s −1 to investigate dynamic recrystallization (DRX) and deformation mechanism. Compared with single-pass compression, multi-pass deformation in the α+β region (890°C) promotes enhanced dynamic spheroidization and significant microstructural refinement, transforming lamellar α into spheroidized and equiaxed α. At 950°C and ε = 0.4, multi-pass produces a higher fraction of C-type ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mo stretchy="false">[</mml:mo> <mml:mo>−</mml:mo> <mml:mn>7</mml:mn> <mml:mspace width="0.25em"/> <mml:mn>12</mml:mn> <mml:mspace width="0.25em"/> <mml:mo>−</mml:mo> <mml:mn>5</mml:mn> <mml:mspace width="0.25em"/> <mml:mn>3</mml:mn> <mml:mo stretchy="false">]</mml:mo> </mml:math> / 60.83°) α/α boundaries, indicating deformation-path-dependent variant selection during phase transformation. Single-pass deformation is mainly associated with CDRX-related substructure evolution, whereas multi-pass promotes localized DDRX-like features in high stored-energy regions, with DRV/CDRX-related evolution remaining important. At 920°C and ε = 0.6, the recrystallized fraction is lower under multi-pass conditions, reflecting deformation-path-controlled recrystallization mechanisms and strain heterogeneity effects.