Low temperature superplasticity through grain refinement in Ti-6Al-4V by a novel route of quench-roll-recrystallise

Abstract

A ‘quench+roll+recrystallise’ method was simulated through compression testing of initially ‘water quenched’ Ti-6Al-4V alloy at a temperature of 973K and rolling strain-rate 100s−1 in order to achieve superplasticity at lower temperature through grain refinement, with a view to increase die life. Subsequent annealing of wire-cut specimens of a rolled sheet at temperatures 1023, 1073, 1123, and 1173K revealed that, the structures became finer and equi-axial in the range of 1–2μm, when annealed at 1073 and 1123K. In compliance to this behavior, a tensile sample from industrially ‘quenched+rolled’ sheet at 973K could produce an elongation of 740% at a temperature of 1073K under a strain-rate of 10−3s−1. Significant elongation of 652% was obtained at further lower temperature of 1023K under a strain-rate of 10−3s−1. Quench-roll-recrystallise technique pushes down superplastic forming temperature to 1023K.