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

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:732

Article

Zhang, Wenjing¹  Ding, Hua¹  Pereira, Pedro Henrique R.^2,3  Huang, Yi^2,4  Langdon, Terence G.² 

[1] Northeastern Univ, Sch Mat Sci & Engn, Shenyang 110819, Liaoning, Peoples R China

[2] Univ Southampton, Fac Engn & Environm, Mat Res Grp, Southampton SO17 1BJ, Hants, England

[3] Univ Fed Minas Gerais, Dept Met & Mat Engn, BR-31270901 Belo Horizonte, MG, Brazil

[4] Bournemouth Univ, Fac Sci & Technol, Dept Design & Engn, Poole BH12 5BB, Dorset, England

关键词: Grain boundary sliding;    Grain refinement;    High-pressure torsion;    Phase transformation;    Superplasticity;    Ti-6Al-4V alloy;   

DOI  :  10.1016/j.msea.2018.07.010

来源: Elsevier

【 摘 要 】

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 similar to 70 and similar to 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 x 10(-4) s(-1). The associated strain rate sensitivity for this low temperature superplasticity was estimated as m approximate to 0.5 which is consistent with flow by grain boundary sliding.

【 授权许可】

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