## 4 Conclusions  
The fabrication of IN718 samples through LPBF and the effect of support structures on the microstructure, composition, hardness, and fabrication cost of samples were studied. Seven identical samples supported by different types of support and different geometrical parameters were fabricated. Comparison between the properties and fabrication cost of samples revealed the following observations:  
* Despite the presence of the same phases detected by XRD analysis in all the samples, the variation in the position of the diffracted peak angles and thus different lattice sizes were found for the specimens. * Among the samples fabricated on different types of support, samples with pin-type (PT53G80) and angled-type (AT53G80) supports had the lowest and highest lattice size and therefore more and less level of precipitations, respectively. Also, in terms of geometrical parameters, the highest value of lattice size and the least precipitation level belonged to the sample fabricated on the densest support with higher thickness and less gap value (AT80G80). These observations were attributed to the heat transfer and cooling rate conditions among different types of support structures that arises from variation in the contact area between sample and support. * It was revealed that the homogeneous or anisotropic behaviors of samples can be tailored using a proper type of support. In terms of the support type, the sample supported by pin-type (PT53G80) had the highest anisotropic behavior ratio among the samples. It was also found out that increasing the gap value as a geometrical parameter leads to more anisotropic behavior. * The variation of the elements between samples was investigated using EDS Analysis. The lowest and highest Ni percentages were observed for the samples supported by Angled-type (AT53G80) and pin-type support (PT53G80), respectively. Also, increasing the gap increased the Ni content while no specific trend was observed for changing the thickness. * Hardness of the samples varied among the samples fabricated with different types of support. A high microhardness value of 460.5 HV was achieved in the as-fabricated IN718 sample built on top of a pin support structure. The results were comparable with the LPBF IN718 in the literature for as-fabricated LPBF sample (322 HV) [21], heat-treated LPBF (335 HV), heat-treated plus hot isostatic pressing (478 HV) [37], and as-fabricated wrought and cast (353 HV) [37]. * In terms of geometrical parameters, the sample fabricated with lower thickness support (AT33G80) showed a higher hardness value compared to the one fabricated with thicker support (AT80G80), However, it was observed that the gap value doesn't affect the hardness value significantly. This variation in hardness value was mainly attributed to the different levels of secondary phases and precipitations between samples. * Among the samples fabricated with different types of support, the deepest melt pools were observed for the pin-type support (PT53G80). * Regarding the influence of thickness, a converse relationship was found between the depth of the pools and the thickness value. It was also found out that change in the gap value doesn't change the dimension of pools considerably. * Despite the fact that raw material powder seems to be expensive, the actual material cost is less than other consumables as well as machine setup and maintenance. * Adjusting the support shape and geometry have the potential of enhancing the specimen properties without adding extra cost. Also, it is possible to increase the hardness and reduce the cost simultaneously. * Samples fabricated with the same support structure but different geometries (e.g., different thicknesses) demonstrate different levels of hardness and different total support costs while having similar total costs. **Author Contributions:** Conceptualization, N.S.M., A.A. and Y.Y. ; methodology, B.B.R., S.T., A.G.R., B.F., M.H. ; software, B.B.R., S.T., A.G.-R., B.F. and M.H. ; validation, B.B.R., S.T., A.G.-R., B.F. and M.H.