Influence of heat treatment on the microstructure and dynamic mechanical properties of laser-melting deposited TC17

The LMD TC17 titanium alloy was subjected to annealing at 800 °C, 850 °C, and 880 °C for 2 hours, followed by furnace cooling. With annealing temperature rising from 800 °C to 850 °C, the α phase width shows an increase. In contrast, the microstructure of the 880 °C treated TC17 is composed of fine lamellar α phases, which form an interwoven basketweave microstructure. The dynamic mechanical properties of the LMD TC17 were evaluated at a strain rate of 3000 s –1 along the parallel (OZ) and perpendicular (OX) building directions. The results indicated that the 880 °C annealed alloy exhibited the best comprehensive mechanical performance, with strength improvements of 158 MPa (OZ) and 168 MPa (OX) compared to forged alloy, while maintaining comparable plasticity. On the one hand, the finest lamellae α contribute to its highest strength; on the other hand, the activation of twins in the loading direction, coupled with the improved deformation uniformity between the α and β phases, enhance the dynamic plasticity of the basketweave microstructure and reduce its adiabatic shear sensitivity. These combined effects explain the superior mechanical performance of the 880 °C annealed materials. This study establishes theoretical foundations for the deployment of additively manufactured TC17 alloy in dynamic service environments.