Mechanical behavior and constitutive modeling of Ti-5553 alloy considering strain rate, temperature, and stress state effects

The effects of strain rate, temperature and stress state on the plastic flow and failure behavior of Ti-5553 (Ti-5Al-5Mo-5V-3Cr) alloy are studied separately. The results indicate that the alloy exhibits strong sensitivity to strain rate and temperature, with the yield and flow stresses increasing as strain rate rises, but its strength and work-hardening capacity weakened at elevated temperatures. The material shows the highest flow stress in uniaxial tension but the lowest in simple shear, due to the stress state effect induced by the evolution of dislocation density and grain boundary migration. Fractographic analysis reveals that under different stress states, the failure behavior gradually transitions with increasing strain rates from ductile fracture to different fracture modes involving dimples, shear facets or adiabatic shear bands. To capture these behaviors for engineering design and calculation, two phenomenological and one physically-based constitutive models are revised to incorporate the effects of strain rate, temperature, and stress state simultaneously. The performance of the models in capturing work hardening, thermal sensitivity, and strain rate effects of the material is analyzed comprehensively.