Effect of direct energy deposition parameters on morphology, residual stresses, density, and microstructure of 1.2709 maraging steel.

In this study, one-dimensional beads and three-dimensional cubes of 1.2709 maraging steel were printed using a laser additive manufacturing (AM) technology. The direct energy deposition (DED) was firstly employed to evaluate the optimal conditions of the single-bead deposition. High-energy (> 64.9 J/mm2) and low-energy (< 64.9 J/mm2) groups of beads were deposited according to a full factorial design of experiment (DOE) and analyzed regarding the optimal aspect ratio between 3 and 5. The low-energy DED was evaluated as the optimal one regarding the required morphology with large process window. The effect of DED process parameters on density/porosity, microstructure, and residual stresses of the cubic specimens was then analyzed. It was found that by reducing the laser energy and print overlap, it is possible to drastically reduce the residual stresses as well as by increasing the powder density. Scanning strategies do not have a strong influence on residual stresses but affect the porosity. Moreover, the porosity is increased with increasing laser energy and print overlap. The best compromise between porosity, residual stresses, and productivity was obtained with a surface energy of 35 J/mm2, a 30% overlap, and a bidirectional-rotation scanning strategy. The presented work highlights the essential experimental data for an upcoming DED of large parts and their characterization suitable for industrial injection molding applications. [ABSTRACT FROM AUTHOR]