Evolution of Microstructure and Mechanical Properties of TB9 Alloy Bar and Wire during Production Process

The evolution of microstructures and mechanical properties of TB9 titanium alloy bar and wire during the production process is systematically studied by means of optical microscope, scanning electron microscope and electron backscattered diffraction. The results show that the TB9 titanium alloy bar and wire with good surface quality, consistent cross-section microstructures and properties can be prepared by vacuum consumable arc melting, forging, rolling and drawing. The as-forged microstructure is composed of randomly oriented coarse β grains and very few dynamic recrystallization(DRX) grains, with an average grain size of more than 1 000 μm. The radial forged microstructure is mainly composed of β grains with the size of about 400 μm, and the increase of cumulative deformation increases the DRX fraction. The microstructure of ϕ10 mm wire rod obtained by multi-pass hot deformation is composed of fine grains of 15 μm, which has obvious hot deformation characteristics. Compared with air cooling, the water cooling of solid solution treatment can obviously uniform the microstructure and obtain distortionless β grains. The hot drawing deformation can further refine the grains and improve the strength of TB9 titanium alloy up to more than 1 100 MPa, while reduces the plasticity.