Superplastic Property of the Ti-6Al-4V Alloy with Ultrafine-Grained Heterogeneous Microstructure

Hiroaki Matsumoto (1) , Takuro Nishihara (1) , Vincent Velay (2) , Vanessa Vidal (2)

1 Kagawa University
2 ICA - Institut Clément Ader

Ti–6Al–4V alloy having a heterogeneous microstructure composed of ultrafine-equiaxed-α-grains and fine-lamellar-α-grains is investigated for microstructural changes during superplastic deformation at temperature of 700 °C. The Ti–6Al–4V alloy having an optimum fraction of fine-lamellar-α-grains exhibits an excellent superplastic property and the highest elongation of 583% (tested at 700 °C 10−3 s−1). This is mainly due to the optimized activation of grain-boundary-sliding and additional accommodation mechanism associated with frequent occurrences of dynamic recrystallization and β precipitation at boundaries during deformation of the heterogeneous starting microstructure. The present result suggests the possibility that optimizing the starting microstructure so as to have an optimum heterogeneous-microstructure serves as an additional stress accommodation mechanism and leads to a large superplastic elongation.

Mots clés: Microstructure; Superplasticity

Domaines: Mécanique des matériaux [physics.class-ph]

Hiroaki Matsumoto, Takuro Nishihara, Vincent Velay, Vanessa Vidal. Superplastic Property of the Ti-6Al-4V Alloy with Ultrafine-Grained Heterogeneous Microstructure. Advanced Engineering Materials, 2018, 20 (1), pp.1700317. ⟨10.1002/adem.201700317⟩. ⟨hal-01693763⟩