The effect of process parameters on laser-deposited TI-6A1-4V

The purpose of this research is to understand how the process parameters surrounding the Direct Metal Deposition (DMD) process affect the properties of the deposition. The powder used in this research is pre-alloyed titanium powder (Ti-6Al4V), containing 6% wt. aluminum and 4% wt. vanadium. The DMD process involves injecting metallic powder into a weld pool created by a high power industrial laser. As the laser traverses across the substrate in a layer-by-Iayer fashion, a fully dense metal is left in its path. A few process parameters involved with the DMD include the laser power, traverse speed, powder flow rate, and gas flow rates. Due to the detrimental effect of oxygen on titanium, oxygen content is one of the main deposition properties of significance involved with this research. In addition to the oxygen content, the powder efficiency, build rate, and build height per layer are also properties of importance. The experiments varied process parameters such as the laser power, CNC velocity, gas flow rate, powder flow rate, and final deposition geometry. In addition to calculating tool path factors such as the line width and build height per layer, the oxygen content, hardness, density, and mechanical properties were determined for each experiment. From these results, it is concluded that increasing the laser power enhanced the powder efficiency and build rate, but eventually negatively affects the oxygen pickup. Also, it is proven that it is beneficial to the deposition properties to increase the powder flow rate or decrease the gas flow rate. The results verified the repeatability of the DMD process and demonstrated that it can produce depositions with equivalent properties to that of commercial Ti-6Al-4V. A successful model for predicting the build height per