Structure, Phase Composition and Mechanical Properties of Hot-Extruded Ti–3Al–2.5V Pipe After Vacuum Annealing

Abstract

The structure and properties of the hot-extruded Ti–3Al–2.5V pipe 90.0 × 20.0 mm in cross section subjected to vacuum annealing are studied using methods of macro-, micro-, X-ray analyses, tensile and Vickers hardness tests. It is shown that during vacuum annealing within the microstructure there is development of α-phase and formation of a more equilibrium (α + β)-condition compared with the condition after hot extrusion, and these changes are reflected in phase parameters, their volume fraction and chemical composition. It is shown that development of recrystallization processes through a pipe cross section also play a specific role in forming the textural condition in different areas of the cross section (outer surface, 1/2 wall thickness, inner surface of the pipe). It is noted that vacuum annealing facilitates a reduction in the scatter of hardness in a pipe cross section and to formation of the combination of mechanical properties with good ductility and a moderate strength level.