## 3 Results  
The proportion of pores for most parameter combinations was between 0.1 and 2.5%. The relative densities of all samples were measured by processing optical photographs of the sample surface using the Image-Pro Plus software. We made cross-sections on the XY side. The pore percent ratio was calculated via the formula  
\[\mathrm{P}=\frac{S_{\mathrm{H}}}{S_{\mathrm{SA}}};100\% \tag{1}\]  
where P is porosity, %;  
SH--area occupied by the pores on the sample's surface, \(\mathrm{\mu m^{2}}\);  
SSA--area of the sample's surface, \(\mathrm{\mu m^{2}}\). It was visible in this range that as the speed increased, the ratio of pores grew up to its maximum value, depending on the power of the laser used. The most noticeable combinations were the combination of the lowest energy parameters and highest speeds (170 W and 1150 mm/s). At such low input energy, the pore ratio was 2.5%. These observations become clearer if we build a porosity histogram from the values of the researched parameters (Figure  
For the purpose of this research, the authors kept to the following technical specifications:  
Defects (micropores) not exceeding 40 \(\upmu\)m were allowed [15]. The relative density of the material must be at least 99.4%. Based on the above, an optimal melting mode for the metal powder composition was found; this mode was used for the 3D printing of the samples for mechanical tests (laser power of 190 \(\pm\) 20 W and laser scanning speed of 855 \(\pm\) 90 mm/s). The samples were oriented vertically on the build platform. The mechanical tests were performed on the samples not subjected to thermal treatment and on the samples subjected to two types of thermal treatment. One of the treatment types was homogenization with subsequent double aging, which is a standard mode widely used for deformed or cast IN718 alloy [22]: 1065 \({}^{\circ}\)C \(\times\) 1.5 h/air cooled, 760 \({}^{\circ}\)C \(\times\) 10 h/cooled in a furnace to 650 \({}^{\circ}\)C (at the speed of 55 \({}^{\circ}\)C/h) and then kept at room temperature for over 8 h. The other treatment type was homogenization with single aging: homogenization at 1150 \({}^{\circ}\)C over 2 h (air-cooled), aging at 700 \({}^{\circ}\)C over 12 h followed by water cooling [23]. The results of the mechanical tests are provided in Table 2 and Figures 6 and 7. The hardness measurement was prepared on the surface of the sample along the Z-axis. The first and the second types of thermal treatment increased the ultimate strength by \(\sim\)21% and 12%, respectively. Meanwhile, thermal treatment reduced tensile deformation by over two times. We must note that after the TT, the samples' hardness increased by \(\sim\)25% and 28%, respectively. However, the values of the mechanical properties of the samples after two thermal treatment types did not differ significantly. Figure 6: Photographs of the samples after the test. (**a**)—sample without thermal treatment; (**b**)—sample after type 1 thermal treatment; (**c**)—sample after type 2 thermal treatment. Figure 7: A graph of the dependency of the mechanical strength on the travel distance. Figure 8 shows the morphology of the destruction of samples after extension tests. The samples subjected and not subjected to thermal treatment had differing microstructures. The fractures found in the areas of the material not subjected to thermal treatment featured dimples, gradual ridges, sharp edges, and flat ridges whose dimensions ranged from 100 to 200 \(\upmu\)m. In the area, many large dimples with a diameter of over 120 \(\upmu\)m were present. Furthermore, after different treatment types, dimples, gradual ridges, sharp edges, and flat ridges were found on the material surface, and the dimensions of those ranged between 80 and 160 \(\upmu\)m, so they were somewhat smaller as compared to the untreated material. It was supposed that defects, unmelted particles, and pores may cause crack propagation at interface boundaries.