Correlative Study on Plastic Response and Formability of Ti-6Al-4V Sheets under Hot Forming Conditions

Abstract In this study, the formability behavior of Ti-6Al-4V alloy sheets under uniaxial and multi-axial loading conditions at 923 K (650 °C), which has received less attention till now, has been extensively investigated by experiments and numerical modeling. Uniaxial tension tests at various strain rates and limit dome height (LDH) tests at the elevated temperature, covering the uniaxial stretch, plane strain, and biaxial stretch deformation modes, were conducted, and the corresponding constitutive models were constructed. Based on the experimentally characterized mechanical properties and associated constitutive laws, finite element simulations of the LDH tests were conducted, and the formability of the investigated material was analyzed using the Marciniak-Kuczyinski theory by employing the von-Mises isotropic yield function and Voce hardening law, including strain-rate sensitivity. At the elevated temperature, a strong positive rate sensitivity effect was observed. Finally, the predicted load-displacement responses of the LDH tests were in good agreement with the measured data. The corresponding formability analysis can contribute to the design of optimal hot forming processes for Ti-6Al-4V sheets.