Abstract
This paper reports the response of microstructure and mechanical properties of a near-β Ti-4Al-1Sn-2Zr-5Mo-8V-2.5Cr (wt.%) alloy after thermomechanical processing. Microstructure observation shows that the precipitation of the primary α phase depends on solution temperature. The highest volume fraction and the smallest size of the secondary α phase precipitated after solution treatment near the phase transition point plus aged treatment at 480 °C. Schematic illustration of the microstructure evolution after different heat treatments was described. Compared with the alloy after solution treatment at β phase region, the alloy has higher ultimate tensile strength after solution treatment at α/β phase region owing to the alloy precipitates primary α phase. It was found that the alloy after solution treatment at 720 °C plus aging treatment at 440 °C has a better ultimate tensile strength of about 1611 MPa, the elongation of about 2.53 %. The main reason is that the precipitation of the secondary α phase contributed to tensile properties substantially.

Key words
near-β titanium alloy, thermomechanical processing, microstructure, tensile properties

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