Influence of build orientation on microstructure, mechanical and corrosion behavior of Inconel 718 processed by selective laser melting

In this work we studied the influence of incline angle on the microstructure, tensile and corrosion response of Inconel 718 (IN 718) samples fabricated via selective laser melting (SLM) with build directions ranging from 0 degrees to 45 degrees. Results reveal that the fraction of Laves phase increases with increasing incline angle and the < 100 > - direction of crystals align along the vertical direction in the samples fabricated with different incline angles. Tensile tests of the printed samples were performed at room temperature and the results showed that the yield strength and ultimate tensile strength increase with increasing incline angle. The highest strength was obtained for the sample with an incline angle of 45 degrees. However, the ductility remains relatively independent of the incline angle. The dependence of microstructure and tensile behavior on the incline angle was rationalized in terms of the temperature gradient during deposition and the ensuing anisotropy in the crystal orientation. The corrosion resistance of SLMed IN 718 in 3.5% NaCl solution increased slightly with increasing incline angle, and this behavior was attributed to the changes in crystallization texture and grain boundary density.