Grain refinement and superplastic flow in a fully lamellar Ti-6Al-4V alloy processed by high-pressure torsion.

Zhang, W., Ding, H., Pereira, P.H.R., Huang, Y. and Langdon, T.G., 2018. Grain refinement and superplastic flow in a fully lamellar Ti-6Al-4V alloy processed by high-pressure torsion. Materials Science and Engineering A, 732 (August), 398 - 405.

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DOI: 10.1016/j.msea.2018.07.010

Abstract

A cold-rolled Ti-6Al-4V alloy was subjected to consecutive heat treatments at 1283 K for 1 h and at 823 K for 3 h in order to produce a fully lamellar microstructure. Thereafter, the material was processed by high-pressure torsion (HPT) through various numbers of turns up to a maximum of 30. It is shown that the HPT processing leads to exceptional grain refinement with average grain sizes of ~ 70 and ~ 50 nm after 20 and 30 turns, respectively. Tensile testing was conducted at 873 and 923 K with different initial strain rates using the material processed through 20 turns of HPT and this gave a maximum superplastic elongation of 820% at the relatively low temperature of 923 K when testing with an initial strain rate of 5.0 × 10−4s−1. The associated strain rate sensitivity for this low temperature superplasticity was estimated as m ≈ 0.5 which is consistent with flow by grain boundary sliding.

Item Type:Article
ISSN:0921-5093
Uncontrolled Keywords:Grain boundary sliding; Grain refinement; High-pressure torsion; Phase transformation; Superplasticity; Ti-6Al-4V alloy
Group:Faculty of Science & Technology
ID Code:31195
Deposited By: Unnamed user with email symplectic@symplectic
Deposited On:04 Sep 2018 08:00
Last Modified:04 Sep 2018 08:00

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