Multi-scale characterization of deformation features and precipitation behavior in a near β-Ti alloy

Abstract

In this paper, the Ti-55511 (Ti-5Al-5Mo-5 V-1Cr-1Fe) alloy was cross-rolled in β field with various rolling reductions, following by short-time aging at 600 °C. The evolution of microstructures and mechanical properties during cross rolling was investigated, and the effect of the deformation features on the precipitation behavior of α phase was elucidate. The results indicated that cross rolling can effectively promote the grain refinement of the β phase, which results in increased tensile strength and weakened texture. Kink bands, stress/strain-induced martensite phases and β-twins were activated in the cross-rolled β matrix, which have a positive influence on the increase of ductility. Besides, the β twin was observed near the β grain boundaries where a high density of dislocations was developed, and the formation of β twins was dependent on the local element content. As a result of soaking in the α + β field, the α phase prefers to precipitate from the pre-existing dislocation structures and martensite phase.