Enhancing Superplasticity of Ultrafine‐Grained Ti–6Al–4V without Imposing Severe Plastic Deformation

Abstract

This study proposes a new regime of thermomechanical treatment composed of temperature‐decreasing step rolling (STEP) and subsequent annealing to fabricate ultrafine‐grained Ti–6Al–4V bulk plates with enhanced superplastic properties. This method utilizes fine martensites as an initial structure to assist in effective grain refinement even without imposing severe plastic deformation. The processed STEP alloys exhibit significant elongation of 706–856% at elevated temperatures. In particular, subsequent annealing at 600 °C induces superplasticity comparable to that obtained by high‐pressure torsion. This is attributed to the acceleration of continuous dynamic recrystallization. The developed thermomechanical process has the advantage of mass‐productivity in contrast to the existing SPD techniques.