β-Texture Evolution During α Precipitation in the Two-Step Forging Process of a Near-β Titanium Alloy

Abstract

β-Texture evolution during consecutive forgings at the single β and (α + β) regions, i.e., two-step forging, was investigated in Ti-6Al-2Sn-4Zr-6Mo alloy. Grain-boundary (GB) α-phase initially formed during forging in the (α + β) region, and interior α-phase subsequently penetrated the β grains. The greater the (α + β) deformation under a constant total forging ratio, the stronger the promotion of interior α precipitation and growth. The {001} β fiber texture intensity increased with increasing forging ratio before the precipitation of interior α. This increase was promoted as the prior-β forging ratio was increased under a constant (α + β) forging ratio. However, the {001} β texture was weakened during the precipitation and growth of interior α. The higher α fraction led to enhanced weakening of the {001} texture. The precipitated α phase had strong $\left\{ {11\bar{2}0} \right\}$ α texture, and the $\left\{ {10\bar{1}1} \right\}\left\langle {11\bar{2}0} \right\rangle$ pyramidal slip system was the most active system in the α phase. The {001} β texture intensity was moderated by a dominant α slip that predominantly activated {110}〈111〉 β slip under the Burgers orientation relationship.