Tube-spinning microstructure and preferential orientation of BT20 alloy

In order to investigate the evolution of microstructure and texture of titanium material in power spinning, backward spinning of BT20 alloy was carried out, and the evolution of surface microstructure and preferential orientation were analyzed using optical microscopy and X-ray diffraction (XRD). Results show that the microstructure in the outer surface of as-spun component is complicated and non-uniform due to repeated actions of tension, compression and shearing. Microstructure inhomogeneity is reduced by multi-pass and large-deformation spinning, and uniform axial fiber microstructure across thickness is obtained. Basal plane {0002} of α grain of titanium alloy is preferred to align with tube surface for radial compression in spinning process. The degree of basal preferential orientation in the inner surface is stably enhanced with the increased deformation. However, the degree in outer surface rapidly increases with deformation within a certain amount, and then decreases to a certain extent.