# Tensile Properties of As-Built 18 Ni300 Maraging Steel Produced by DED
## 3 Results and Discussion  
### 18 Ni300 Mechanical Characterisation  
The results of the performed tensile tests are shown in Figure 4(a),b for the engineering stress-engineering strain curves true stress-true strain, respectively. The yield strength, ultimate tensile strength and elongation to fracture of deposited 18 Ni300 are shown in Table 4. The mechanical strength between the horizontal and vertical specimens is relatively similar, with the average yield strength and ultimate tensile strength in both directions varying by 6.27% and 1.71%, respectively. This similarity in material strength between differently orientated specimens is expected, considering that despite the difference in cutting procedure, both specimens are comprised of the same material. The difference in metallurgical features amongst the different specimens is predominately observed in the difference of plastic behaviour, as explained further in this work. Research on the mechanical  
Figure 5: Monotonic tensile test results for the deposited 18 Ni300 specimens: engineering stress-engineering-strain curves (**a**) and true stress–true strain (**b**) curves. \begin{table}
\begin{tabular}{l c c c c} \hline \hline
**Location** & **Specimen** & \begin{tabular}{c} **Thickness** \\ **[mm]** \\ \end{tabular} & \
\begin{tabular}{c} **Width** \\ **[mm]** \\ \end{tabular} &
\begin{tabular}{c} **Section Area** \\ **[mm\({}^{2}\)]** \\ \end{tabular} \\ \hline \multirow{3}{*}{Horizontal} & MH1 & 1.031 & 2.079 & 2.14 \\  & MH2 & 1.034 & 2.088 & 2.16 \\  & MH3 & 0.964 & 2.074 & 1.99 \\ \hline \multirow{3}{*}{Vertical} & MV1 & 1.038 & 2.090 & 2.17 \\  & MV2 & 1.024 & 2.084 & 2.13 \\  & MV3 & 1.019 & 2.084 & 2.12 \\ \hline \multirow{3}{*}{Bimetallic} & MH1 & 1.033 & 2.083 & 2.15 \\  & MI2 & 1.038 & 2.088 & 2.17 \\ \cline{1-1}  & MI3 & 1.026 & 2.075 & 2.13 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Specim dimensions, measured at the gauge length. Three measurements were conducted along gauge length, with presented value being an average of the three values. Section area computed with average thickness and width values. properties of differently oriented DED-produced samples reached similar conclusions, with the yield strength and ultimate tensile strength of DED-W deposited Ti6 Al4V by [PERSON] et al. [36] in the horizontal and vertical directions showing a difference of 2.59 and 6.34% for the yield strength and ultimate tensile strength, respectively. [PERSON] et al. [37] concluded that the build orientation effect on mechanical properties of DED-produced 316 did not have statistical significance, according to the ANOVA method, in the samples' ultimate tensile strength. The disparity in the results within the horizontal direction is considerable, with the yield strength oscillating between 810.5 and 1029.1 MPa. The difference in the total elongation between the horizontal and vertical specimens was also of note, with the horizontal specimen displaying more ductility on average than its vertical counterpart. This is partly expected due to the nature of additive processes, as newly deposited layers require the remelting of previously solidified material, generating microstructural anisotropy that affects the properties of the component, as reported in similar research [38; 39]. Other research reports the presence of weak interfacial layers as a cause for the recorded anisotropy [40]. A comparison regarding the ultimate tensile strength \(\sigma_{uts}\) in the literature for DED-processed 18 Ni300 in its as-built condition was performed, with the results shown in Figure 6. The ultimate strength's larger values for the AM-produced parts is not uncommon [23; 40], considering the fine microstructure that arises from the fast cooling rates associated with AM [23].