# A Prediction Model for Additive Manufacturing of Inconel 718 Superalloy
It was also concluded that there was a strong correlation between the energy density and the formation of pores, as employing the higher energy density reduced the level of porosity. A detailed study by [PERSON] et al. [33] showed that the laser power and scan speed have different influences on the formation of pores in the IN718 LPBF-fabricated samples. The authors observed a rapid decrease in the level of porosity with an increase in laser power, whereas a linear trend was found by reducing the scan speed. Consequently, a proper combination of laser power and scanning speed was recommended for obtaining a fully dense part. The laser process parameters have an influence on the density and mechanical properties of as-fabricated LPBF samples [34]. In a statistical study performed on LPBF, the laser power values were varied at three different levels to fabricate IN718 samples. It was revealed that increasing the laser power to a specific value (200 W) brings about parts with a lower porosity level. Additionally, in terms of mechanical properties, the highest yield strength of 775 MPa, the ultimate strength of 1055 MPa, and elongation of about 30% were obtained [35]. Lower surface quality and a higher porosity level in the LPBF-processed IN718 samples were observed when the scanning speed was increased [32; 36]. One of the drawbacks of the LPBF process is the relatively poor surface finish and dimensional accuracy of the final parts. Although LPBF is widely utilized for the fabrication of components in aerospace and biomedical industries, it is still challenging to achieve the high level of precision required for some critical parts. Achieving a level of accuracy of up to \(\pm\)20-50 \(\upmu\)m is difficult for the 3D printing components [37]. For this reason, many studies considered dimensional accuracy as one of the main outputs in the optimization of processing parameters [28; 38; 39; 40; 41; 42]. [PERSON] et al. [43] concluded that lowering the layer thickness results in denser parts with higher dimensional accuracy and minor improvements in mechanical properties and microhardness. In another study, the effect of hatch distance on the density of LPBF-fabricated IN718 was revealed. It was found that a higher level of densification occurs by reducing the hatch spacing [44]. [PERSON] et al. [45] investigated the impact of laser power and scanning speed on the geometrical accuracy of the fabricated samples. They found that a lower speed and higher laser power significantly reduced the geometrical accuracy of the fabricated IN718 samples. Similar observations were reportedin another study by [PERSON] et al. In another study performed by [PERSON] et al. [46], the effect of process parameters on the distortion of the LPBF-fabricated IN718 samples was investigated through simulation analysis. Using Simufact Additive (SA), a simulation software, it was found that each set of process parameters have a different effect on the quality of the part. For example, it was seen that as the laser power increased, the distortion effects increased and that the distortion could be reduced by increasing the scan speed. However, no experimental measurements were used in this study to evaluate the output of the simulation model. The distortion analysis and the dimensional accuracy can also be evaluated by investigation of the variation in size of the sample height, as the most affected dimension fabricated along the building direction. The importance of this parameter can be attributed to the fact that the deviation in height of the sample can prevent uniform spreading of the powder, leading to failure in fabrication due to the collision between a part and the recoater. In this case, several studies investigated the effect of processing parameters on the dimensional accuracy; the height of the sample was considered as an important criterion [24; 47; 48; 49]. Similarly, in this study the sample height was selected as an output to represent the dimensional accuracy and the deviation from the designed value.