The effects of forging strategies on microstructures and mechanical properties of a Ti–5Al–5Mo–5V–1Cr–1Fe near β-titanium alloy
Xianghong Liu, Xiaolong Ren, Xinglong An, Yu Chen, Tao Wang, Song Ni, Min Song, Hao Zhang, Yuxuan Du
Abstract
The present study systematically investigated the influence of forging strategies on the microstructures and deformation behaviors of a Ti–5Al–5Mo–5V–1Cr–1Fe (Ti-55511) near β-titanium alloy. Microstructure analysis revealed that the as-cast alloy exhibited a basket-weave structure predominantly comprised of lamellar α phase. Three different forging methods were used to adjust the morphology of the primary α phase during the final two forging steps: 1) dual-phase (825 °C) + dual-phase forging (DD sample), 2) dual-phase + β single-phase (900 °C) forging (DS sample), and 3) β single-phase + dual-phase forging (SD sample). After standard heat treatment, the DD samples exhibited equiaxed α p due to sufficient deformation in dual-phase region, while DS samples transformed into lamellar shape due to α p reforming during the cooling process of the final β single-phase forging. In contrast, the SD samples displayed short-rod α p due to reforming in the single-phase region and insufficient deformation in the dual-phase region. All these α p and β t phases can hinder dislocation motion to enhance the strength. The DS sample exhibited the best combination of strength, ductility, and impact toughness. During tensile deformation, planar dislocation slip and { 10 1 ‾ 1 } twinning were dominant in the α p , while wave slip occurred in the β t phase. The fracture behavior transitioned from brittle to ductile after forging and heat treatment. Overall, this study offers a practical and effective method for optimizing the mechanical properties of the Ti-55511 alloy.