The dynamic softening identification and constitutive equation establishment of Ti-6.5Al-2Sn-4Zr-4Mo-1W-0.2Si alloy with initial lamellar microstructure

The high-temperature deformation behavior of Ti-6.5Al-2Sn-4Zr-4Mo-1W-0.2Si alloy with initial lamellar microstructure was investigated through performing hot compression experiments at temperatures of 940-1,030 & DEG;C and strain rates of 0.001-10 s(-1) on the Gleeble-3500 simulator. Three kinds of typical flow curves corresponding to different strain rates were distinguished. The deformation activation energy and Zener-Hollomon parameter were obtained through kinetic analysis. By comparing saturated dislocation density with the critical density for dynamic recrystallization, dynamic softening behaviors were identified and verified by the Poliak-Jonas criterion. Furthermore, a piecewise physical-based constitutive model incorporating dynamic softening behaviors was constructed. Finally, microstructures deformed under different deformation conditions were analyzed to further verify the softening behaviors determined by identification criterions.