Compressive creep damage of Ti–6Al–4V ELI alloy with bimodal structure at room temperature

Abstract

The compressive creep performance of Ti alloy is critical for the application of submersibles due to the pressure hull of deep-diving equipment mainly subjected to the seawater pressure during its service. The compressive creep behaviors and the corresponding deformation mechanism of Ti–6Al–4V ELI alloy under different applied stress amplitudes were investigated. It was found that the stress threshold for Ti–6Al–4V ELI alloy produced significant compressive creep damage was 0.8 times yield strength (Rp0.2), and the primary mechanism was {101‾0}⟨112‾0⟩ prismatic slip. Specifically, a large number of prismatic slips were preferentially activated in the αp grains with a relative high Schmid factor when the applied stress amplitude was greater than 0.8Rp0.2. As the applied stress amplitude increases, the prismatic slips were also activated in the αlath. Meanwhile, the Burgers relationship between αlath and βlamellae gradually destroyed due to the dislocation pile-up at the αlath/βlamellae interface. This investigation provides data support for the compressive creep performance evaluation of Ti–6Al–4V ELI pressure hull.

Keywords

• Compressive creep
• Ti–6Al–4V ELI
• Bimodal structure
• Prismatic slip
• Deformation damage