Microstructure and Mechanical Properties of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si Alloy Fabricated by Arc Additive Manufacturing with Post Heat Treatment

Wire arc additive manufacturing (WAAM) can achieve low-cost, short-cyclemanufacturing of titanium alloys and has promising application prospects. In this paper, themicrostructure and mechanical properties of both as-deposited and heat-treated Ti-6.5Al-3.5Mo-1.5Zr-0.3Si(TC11) alloys fabricated byWAAM were investigated. The results show that continuousgrain boundary α(αGB) phase and basket-weave microstructure can be observed in the as-depositedTC11 alloy. And the as-deposited alloy exhibits high ductility but low strength. After the annealingtreatment, the microstructure becomes thicker and the strength becomes lower. Accordingly, a duplexheat treatment near β transus was designed. We can observed that the content of α phase in themicrostructure was gradually decreased, and the continuous αGB was broken gradually. As thetemperature increases, the strength and ductility of TC11 alloy increase first and then decrease, andthe best comprehensive mechanical properties are achieved at 970°C.