Enhancement of superplasticity of the Ti-6Al-4V alloy via ultrafine grained heterogeneous microstructural control and metastable microstructural control

Abstract : Ti-6Al-4V alloy (hereafter designated as Ti-64 alloy) is widely used in aerospace applications due to high specific strength and high formability associated with superplasticity. This work presents new type of microstructural control for the enhancement of superplasticity; it focuses on an ultrafine grained heterogeneous microstructural control and a metastable microstructural control. This concept of microstructural control is for increasing the grain boundary sliding activity associated with the enhancement of stress accommodation mechanism. With respect to the Ti-64 alloy having a heterogeneous microstructure composed of ultrafine-equiaxed-α-grains and fine-lamellar-α-grains, it is found that the optimization of fraction of fine-lamellar-α-grain results in the highest elongation to fracture as compared to the case of the ultrafine-grained-homogeneous microstructure, indicating that the enhancement of superplasticity is achieved by heterogeneous microstructural formation. On the other hand, regarding the deformation of the Ti-64 alloy having a metastable microstructure containing an α′-martensite phase, it is interestingly found that discontinuous dynamic recrystallization (DDRX) frequently occurs during high temperature deformation, leading to an additional accommodation mechanism. Thus, the present results suggest the possibility that optimizing the starting microstructure so as to have an optimum heterogeneous microstructure and a metastable microstructure containing an α′-martensite phase serves as an additional stress accommodation mechanism and leads to a large superplastic deformation.
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https://hal-mines-albi.archives-ouvertes.fr/hal-02384925
Contributor : Vanessa Vidal <>
Submitted on : Thursday, November 28, 2019 - 3:42:30 PM
Last modification on : Friday, January 10, 2020 - 9:09:48 PM

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  • HAL Id : hal-02384925, version 1

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Hiroaki Matsumoto, Vincent Velay, Vanessa Vidal. Enhancement of superplasticity of the Ti-6Al-4V alloy via ultrafine grained heterogeneous microstructural control and metastable microstructural control. Ti2019 - The 14th world conference on titanium, Jun 2019, Nantes, France. ⟨hal-02384925⟩

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