Enrique Alabort, Engineering Science Department, Oxford University

Studying Superplasticity in Ti-6Al-4V
When Feb 16, 2015
from 02:00 PM to 03:00 PM
Where LR8, IEB Building, Engineering Science
Contact Name
Contact Phone 01865-273925
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Superplasticity is vital in many industrial fields — medical, defense, aerospace, transport and sports among others — for the fabrication of metallic components of complex geometry. The inherent peculiarity of the effect has kept theorists fascinated for many years. But significant controversy exists concerning the deformation mechanism which is operative. In particular, unequivocal evidence that supports precise details of the accommodation process — whether it is diffusion, dislocation accommodated, a combination of both or some sort of cooperative grain boundary — is unavailable. Traditionally, surface studies have been used to characterise superplasticity. These studies have relied in post-mortem observations. However, novel in-situ testing techniques are potentially significantly more powerful for the study of high-temperature deformation mechanisms. In this talk, the mechanisms of superplasticity in Ti-6Al-4V are discussed. In addition, superplasticity is studied under constant strain-rate conditions; this has allowed the regime of superplasticity to be pinpointed. For design purposes, this understanding is translated into validated material laws which are accurate and which capture the relevant phenomena. Microstructurally explicit material laws are proposed based upon the micromechanical modes of deformation which are shown to be operating. In the final part of the presentation, modelling is used to simulate an industrially-relevant manufacturing process which is important for the construction of hollow, lightweight structures which are of significant practical importance for the aerospace sector.