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

• Published in: Advanced engineering materials 2018-01, Vol.20 (1), p.n/a
• Main Authors: Matsumoto, Hiroaki, Nishihara, Takuro, Velay, Vincent, Vidal, Vanessa
• Format: Article
• Language: English
• Subjects: accommodation mechanism; dynamic recrystallization; Engineering Sciences; low‐temperature‐superplasticity; Mechanics; Mechanics of materials; Ti‐6Al‐4V alloy; ultrafine‐grained microstructure
• ISSN: 1438-1656; 1527-2648
• DOI: 10.1002/adem.201700317

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. The ultrafine‐grained Ti–6Al–4V alloy having an optimum fraction of highly‐elongated‐α‐grains exhibits the highest tensile 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.