The Microstructure and Texture Evolution of Large-Sized Metastable β-Titanium Alloy Bar during Forging Processes

To weaken texture and homogenize microstructure, the evolution of microstructure and texture of large-sized metastable beta-titanium alloy Ti55511 in industrial scale during multiple rounds of forging was studied by electron backscatter diffraction. The forging process, including alternate upsetting and stretching was used. However, the microstructure and texture change much from the center to the edge of the large-sized bar after different forging passes. The volume fraction of alpha increases from the center to the edge of the sample, and with decrease in forging temperature. The spherical alpha phase forms until the ninth forging pass. The texture characteristics are basically fixed in the first forging pass in (alpha + beta)-phase (the fourth pass). The texture of the sample after forging passes is characterized by the formation of <001> fiber at the edge of the sample. In the center of the large-sized bar, there are strong <110> and <111> fiber textures after the fourth pass. The volume faction of <100> fiber texture keeps increasing trend from central areas to areas at the edge, whereas the <110> fiber texture keeps decreasing trend from central areas to areas at the edge from the fourth pass.