## 3 Results and Discussion
Therefore, the 316 LLS part, which contains a higher amount of austenite (as seen in Figure 8 for \"316 LLS\"), has a higher hardness than the 316 LHS part, which contains more ferrite (as seen in Figure 8 for \"316 LHS\"). Moreover, the presence of annealing twins in the 316 LLS part (Figure 7b) can also be considered another reason for the increased hardness [38]. The obtained hardness values are consistent with those obtained for 316 L material produced by other methods [39; 40; 41]. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & & & & & & & & & & \\ \hline
**Point** & **O** & **Al** & **Si** & **S** & **Cr** & **Mn** & **Fe** & **Ni** & **Cl** \\ \hline c-1 & 3.38 & 0.14 & 1.26 & 1.43 & 15.23 & 0.85 & 68.60 & 9.09 & **–** \\ \hline c-2 & 2.50 & 0.18 & 1.39 & 1.14 & 16.84 & **–** & 69.90 & 8  
Based on the obtained data, the study continued with the parameters that gave the best results, and the effect of layer thickness was investigated. For this purpose, parts were produced under the LLS conditions that yielded better results, and the mechanical characterization of these parts was performed. The decrease in porosity affects the mechanical properties and yield strength of 316L stainless steel parts. The density of 316L stainless steel parts produced by the FDM method generally depends on the chemical components of the filament used and the production parameters. During the production of 316L stainless steel by FDM, weaknesses in the bonding between layers or microscopic voids (porosity) can affect the material's density. These types of microstructural defects can disrupt the homogeneity of the material during production, leading to a lower density compared to traditional casting methods. During the processing of the filament, heating and cooling rates are a significant factor that can considerably affect the density [12; 42]. In this study, the highest density value was achieved in parts produced with a 100 \(\upmu\)m layer thickness, with the highest theoretical density value reaching 96%. A yield strength of 262 MPa was obtained at 96% density. [PERSON] et al. [43] reported that decreasing layer thickness increases the contact area between layers, thus increasing the density, which is consistent with the current study, where lower layer thicknesses resulted in lower porosity values. In a similar study, a porosity value of 4% was achieved after sintering at 1350 \({}^{\circ}\)C [44]. [PERSON] et al. [9] achieved a density higher than 95%. The obtained results are consistent with the studies reported in the literature. Figure 10 shows the graph of the density variation based on layer thickness. It is clearly observed that as the layer thickness increases, the density value decreases. It is believed that the lower density observed in the sample with a 200 \(\upmu\)m thickness, compared to the sample with a 300 \(\upmu\)m thickness, is due to the inhomogeneous structure. The porosity distribution at 100 \(\upmu\)m (best) and 400 \(\upmu\)m (worst) layer thicknesses was statistically analyzed and presented in a graph. An average porosity size of 7 \(\upmu\)m was observed at 100 \(\upmu\)m layer thickness, while at 400 \(\upmu\)m, the average porosity size was 9 \(\upmu\)m. The maximum porosity size measured was 25 \(\upmu\)m at 100 \(\upmu\)m and 35 \(\upmu\)m at 400 \(\upmu\)m. These results are consistent with those reported in the literature [7; 43]. Additionally, the density data further validate this result, with 96.36% (3.64% porosity) for the 100 \(\upmu\)m layer and 91.22% (8.78% porosity) for the 400 \(\upmu\)m layer (Figure 11). Figure 9: Hardness values of the samples. The microstructural images obtained from the samples (Figure 12) corroborate the density measurements. In the microstructure of the part produced with a lower layer thickness (Figure 12a), equiaxed austenite grains and a limited number of grain boundary porosities are observed, while in the microstructure of the part produced with a higher layer thickness (Figure 12b), a non-uniform pore size distribution is evident.