## 3 Results and Discussion  
In this study, a full-solid specimen was considered as a specimen with 100% density equivalent. The stress-strain relations of 316L and 17-4 PH stainless steel full-solid specimens obtained from the tensile test are presented in Figure 7. It can be seen that the 17-4 PH specimens have more strength than the 316L specimens. The 316L specimens have ductile behavior, while the 17-4 PH specimens have brittle behavior. The average values of the mechanical properties of the 316L and 17-4 PH full-solid specimens obtained from the tensile test are shown in Table 3. The yield and ultimate strength of the 17-4 PH specimens obviously show more values than the 316L specimens. In contrast, the elastic modulus of both 316L and 17-4 PH specimens shows similar values. The average elongation value of the 316L specimens is greater than that of the 17-4 PH specimens, i.e., 54.63% and 3.32% elongation, respectively. According to a datasheet provided by Desktop Metal, the yield strength and ultimate strength of the 316L specimens are 165 MPa and 494 MPa, respectively. With the same test standard, the yield strength and ultimate strength experimentally obtained in this study are approximately 96.81% and 97.63% of those in the datasheet, respectively. Additionally, the yield strength and ultimate strength of the 17-4 PH specimens are 660 MPa and 1042 MPa, \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Material** & **Elastic Modulus 1 (GPa)** & **Yield Strength 1 (MPa)** & **Ultimate Strength 1 (MPa)** \\ \hline
316L & 167.20 (4.00) & 159.74 (6.95) & 482.31 (14.30) \\
17-4 PH & 160.82 (3.45) & 653.25 (8.72) & 809.89 (16.02) \\ \hline \hline \end{tabular} \({}^{\dagger}\)Standard deviation is depicted in the brackets (SD).  
\end{table} 
Table 3: The mechanical properties of 316L and 17-4 PH stainless steel full-solid specimens. respectively, while the yield strength and ultimate strength experimentally obtained in this study are approximately 98.98% and 77.72% of those in the datasheet, respectively. This discrepancy could have occurred due to various factors in the manufacturing processes. For this reason, an experimental study is vital for assessing the mechanical properties of the AM parts to reflect their actual behavior in different printing contexts. The stress-strain curves of infill specimens made from 316L and 17-4 PH stainless steel are shown in Figures 8 and 9, respectively. The 316L infill specimens show lower strength and behave as a ductile material, while the 17-4 PH infill specimens show more strength and behave as a brittle material. Note that the shift of the curves at a strain value of 2% in Figure 8 is the effect of the test speed change. Meanwhile, the yield point of the 17-4 PH specimens cannot be indicated since the specimens failed near the ultimate strength. The stress-strain curve comparison of the infill and full-solid specimens made from 316L and 17-4 PH stainless steel are illustrated in Figures 10 and 11, respectively, to show the distinctness of material behaviors when the full-solid specimens have their weight reduced using an infill pattern. Moreover, the mechanical properties of 316L and 17-4 PH infill specimens obtained from the tensile test and computed from the analytical method described in Section 2.4 are compared in Table 4. It can be observed that the values of the elastic modulus of the 316L and 17-4 PH infill specimens are similar in each relative density. Figure 7: The stress–strain curves of 316L and 17-4 PH stainless steel full-solid specimens. Figure 8: The stress–strain curves of 316L stainless steel infill specimens. Figure 9: The stress–strain curves of 17-4 PH stainless steel infill specimens. Figure 11: The comparison of stress–strain curves between infill and full-solid specimens made from 17-4 PH stainless steel. Figure 10: The comparison of stress–strain curves between infill and full-solid specimens made from 316L stainless steel.