Effects of solution-aging treatments on microstructure features, mechanical properties and damage behaviors of additive manufactured Ti-6Al-4V alloy

摘要

Hot isostatic pressing (HIPing) treatment was generally carried out to eliminate possible defects and to homogenize the microstructure for Ti-6Al-4V alloy fabricated by the Electron beam rapid manufacturing (EBRM) process. But the HIPed alloy with relative coarse lamellar microstructure exhibited a low strength compared to the as-built one. Post solution-aging treatments were necessary to optimize the HIPed alloy's tensile properties. So far, the relationship between the heat-treated microstructure features and corresponding mechanical properties of EBRM-produced Ti-6A1-4V has not been completely understood. Therefore, in the present work, solution-aging treatments under various solution temperatures (930 °C-990 °C) were applied to the HIPed Ti-6A1-4V produced by the EBRM, and the corresponding microstructures and mechanical properties were investigated. The results showed that solution-aging treatments could increase the HIPed alloy's tensile strength but decrease its ductility. With increasing solution temperature, the tensile strength presented an upward tendency until to 980 °C, whereas a decrease after 990 °C solution treatment. The variation in tensile properties was caused by the microstructures evolved with solution temperatures. In-situ tensile results showed that the deformation and damage behaviors of the alloy were also highly affected by the solution temperatures. Owning to a decrease of content of the α_p with increase of solution temperature, the alloy at high solution temperature presented superior resistance of crack initiation but inferior resistance of crack growth than that at low solution temperature.