Effect of Cu concentration on the semi-solid formability and mechanical properties of Ti-Cu alloy

Abstract:

The formability during semi-solid deformation of Ti-Cu alloys and its mechanical properties after semi-solid forging are investigated. The formability is evaluated by upsetting and die forging tests. Tensile test is also performed to study the mechanical properties of Ti-Cu alloy after semi-solid forging. The results show that low upsetting force can be obtained in the semi-solid state ranging from 1000 °C to 1150°C, which is better than by conventional processing. Die forging tests show excellent workability with a forging ratio of 75% at the temperatures ranging from 1000 °C to 1050°C. The Ti2Cu phase increases with the increase of Cu concentration, and more liquid precipitates during semi-solid deformation at higher temperatures and Cu concentrations, which relaxes the stress concentration caused by solid deformation and improves the formability. Tensile test reveals that semi-solid forged Ti-Cu alloy exhibits higher strength and lower ductility than conventional forged alloy. The Ti-Cu alloy has lower ductility and higher strength with the increasing of Cu concentration. The difference in tensile properties is attributed to the varieties of Ti2Cu precipitates at different Cu concentration and semi-solid forging temperature.