Effect of laser additive manufacturing parameters on hardness and geometry of Inconel 625 parts manufactured by direct laser metal deposition

This research investigates the effect of process parameters on the geometry and properties of In625 parts, manufactured by the direct laser metal deposition (DLMD) process. For this purpose, eight parts, consisting of 5 layers on top of each other, were manufactured, and the effect of laser power, laser focal plane position, and scanning speed on the height, width, and surface smoothness of each of them was investigated using design of experiment (DOE). The experimental results showed that the height of the parts manufactured by 800 W/mm and 200 W/mm of energy density is 3.69 mm and 6.12 mm, respectively. The thickness of the parts manufactured by 80 W/mm and 200 W/mm of energy density is 1.5 mm and 3.47 mm, respectively, and the mass of powders deposited at the scanning speed of 2.5 mm/s and 1.5 mm/s is 3.4 gr and 5.66 gr, respectively. Also, the combination of experimental and DOE data showed that the effect of laser power and scanning speed on the thickness of the parts is more significant than the effect of laser focal plane position and is inversely related to scanning speed, and directly related to the laser power. Also, the effect of scanning speed and laser focal plane position on the height of the parts is more significant than the effect of laser power. It is also shown that the effect of laser power and laser focal plane position on the surface smoothness is more significant than other parameters.