Laser additive manufacturing of TI-6AL-4V alloy at a high deposition-rate using a rectangular laser spot

Ti-6Al-4V is difficult to machine via milling or turning; therefore, near-net-shape manufacturing offers significant advantages as it can reduce the amount of material to be subtracted down to the final dimension. Additive manufacturing can be used to accomplish near-net-shapes, but its low deposition rate makes it less attractive for industry. In the present study, we investigated how a rectangular laser spot with a top hat intensity distribution can be used to increase the deposition rate of Ti-6Al-4V for powder-based laser direct energy deposition. Deposited single tracks, layers, and solid bodies were built to study the effect of processing parameters on the microstructure evolution. Post-thermomechanical treatment was carried out at different temperatures and strain rates using a deformation dilatometer. Track geometry, bonding defects, and microstructure were analyzed. The high deposition rate was increased up to 5 kg/h, while the process remained stable. Global shielding from the surrounding air is mandatory to prevent oxidation since the deposited volume heats up quickly.