# Tensile Properties of As-Built 18 Ni300 Maraging Steel Produced by DED
## 4 Conclusions  
Three distinct samples of 18 Ni300 Maraging steel were successfully manufactured, with the samples subsequently subjected to tensile testing, and the originated fracture surfaces analysed via SEM, as well as a microhardness analysis. The conclusions of these studies are as follows:  
* The yield and ultimate tensile strengths of the horizontal and vertical specimens are similar, with the mean of each property varying 6.27% and 1.71%, respectively, between both samples, with larger values for vertical specimens;
* There is a significant dispersion in the stress-strain curves of the horizontal specimen, ranging from 810.5 to 1029.1 MPa, which may be attributed to the microstructural heetereogeneity resulting from the dendritic and grain size, influenced by remelting and reheating of successive layers;
* The mean of the elongation to failure in the horizontal specimen was 94.7% larger than the vertical specimen (18.3 and 9.4% in the horizontal and vertical, respectively), attributable to larger porosities in the latter specimen, which led to premature failure;
* The bimetallic specimen yielded at stresses in the range of AISI 1045's yield strength. The DIC-computed strain field instantly before fracture indicated that necking and subsequent fracture occurred entirely in the area comprised of AISI 1045, indicating good adhesion between the substrate and the deposited geometry;  
Figure 11: Microhardness graph across the printed wall from the bottom to the topmost region.  
Figure 12: Optical microscopy images: (**a,b**) near the bottom and close to the middle of the printed wall; and (**c**) distribution of dendritic structure in different orientation observed in some neighbouring fused regions.  
* The fracture surface of the specimens was comprised of dimples, although the microprosity size in the vertical specimen was seen to be larger, indicating that the stress concentration in these specimens was larger, leading to premature failure.
* The average microhardness across the deposited wall-like geometry was \(392\pm 21\) HV0.3. The fluctuations along the geometry are attributed to the microporosity distribution.  
Conceptualization, O.E., J.G., R.A. and R.S.; methodology, O.E., R.S. and J.G.; validation, J.G. and O.E.; formal analysis, A.R. and A.D.J.; investigation, J.G. and R.S.; resources, A.R. and A.D.J.; writing--original draft preparation, J.G. and R.S.; writing--review and editing, A.R., A.D.J. and O.E.; visualization, J.G., R.A. and O.E.; supervision, A.R. and A.D.J.; funding acquisition, A.R. and A.D.J. All authors have read and agreed to the published version of the manuscript.  
The authors would like to acknowledge the funding of the PhD scholarship with the reference UI/BD/150684/2021, funded by Fundacao para a Ciencia e Tecnologia (FCT). The authors acknowledge the funding through the Add.Strength project, with reference PTDC/EME-EME/31307/2017, funded by FEDER and FCT. The authors would further acknowledge the funding through the ADDing project, with reference POCI-01-0145-FEDER-030490, funded by FCT and FEDER. The authors would like to acknowledge the funding acquired through the MAMTool project, with reference PTDC/EME-EME/31895/2017, funded by FEDER and FCT. The authors would like to thank the support provided by Fundacao para a Ciencia e a Tecnologia of Portugal (FCT) and IDMEC under LAETA-UIDB/50022/2020.  
The authors declare no conflict of interest.  
The following abbreviations are used in this manuscript:  
AM Additive manufacturing  
DED Directed energy deposition  
SLM Selective laser melting  
SLS Selective laser sintering  
SEM Scanning electron microscopy  
DLS Dynamic light scattering  
PSD Particle size distribution  
OES Optical emission spectroscopy  
DIC Digital image correlation  
wEDM Wire electrical discharge machining