## 3 Results  
### MSS Measurements  
Multiple (>5) MSS measurements were conducted on each of the eight SLM samples, with approximately 20 unloading segments in each test. Recall that each unloading produces one data point on the indentation stress-strain curve. Therefore, a total of roughly 20 data points on the indentation stress-strain curve were obtained for each SLM sample. [PERSON] and [PERSON] [17] explored and validated scaling factors used to convert MSS stress-strain curves to UTT stress-strain curves have been established in their prior work using a combination of FE models and experiments. The authors of this work demonstrated that these scaling factors account for the inherent heterogeneity of the deformation induced in the indentation experiments as well as the differences in the stress (and strain) states compared to the uniaxial tests. In this same work, they established equations which can be used to convert indentation stress-strain curves to uniaxial stress-strain curves, and they are summarized below:  
\[\varepsilon_{eMSS}=\frac{\sigma_{MSS}}{E_{eff}} \tag{10}\]  
\[\varepsilon_{PMSS}=\varepsilon_{TMSS}-\varepsilon_{eMSS} \tag{11}\]  
\[\varepsilon_{TUTT}=\left(\frac{\varepsilon_{eMSS}}{2}\right)+\left(\frac{ \varepsilon_{PMSS}}{1.3}\right) \tag{12}\]  
\[\sigma_{UTT}=\frac{\sigma_{MSS}}{2.2} \tag{13}\]  
where \(\varepsilon_{eMSS}\) is the elastic strain from MSS analysis, \(\varepsilon_{PMSS}\) is the plastic strain from MSS analysis, \(\varepsilon_{TMSS}\) is the total strain from MSS analysis, \(\sigma_{MSS}\) is the stress from MSS analysis, \(E_{eff}\) is the indentation modulus of the sample, \(\varepsilon_{TUTT}\) is the total strain in UTT, and \(\sigma_{UTT}\) is the stress in UTT. In the linear elastic portion of the UTT stress-strain curve, only the first term in Equation (9) is used (i.e., the plastic strain in this regime is assumed to be zero). A comparison of the UTT stress-strain points estimated from MSS measurements using Equations (10)-(13) is compared with the direct measurement of UTT stress-strain curves for Sample number 8 in Figure 5.  
It is seen that the data points extracted from MSS measurements are in good agreement with large portions of the measurements obtained directly from UTT protocols. The highest discrepancy between these curves was seen in the elastic-plastic transition. These observations are consistent with results presented by [PERSON] and [PERSON] [17] in their indentation simulations, and the authors have concluded that these differences are likely a consequence of the differences in the elastic-plastic transition in the MSS and UTT test methods. Due to the differences in geometry between UTT and MSS, the transition from elastic deformation to constant hardening behavior in the material occurs at a different rate. In UTT, load is applied over a constant cross-sectional area, so there is a bilinear stress-strain response where the first linear segment represents the elastic response of the material while the second linear segment represents the plastic response of the material where strain hardening is constant. In MSS, the elastic-plastic transition region is nonlinear because the contact radius between the indenter and sample is continuously changing as load increases. [PERSON] et al. [18] have demonstrated that the values of [PERSON]'s moduli of the samples can be estimated using Equation (3) and the MSS measurements of \(E_{eff}\) obtained from the initial elastic portions of the indentation stress-strain curves. These estimated values for the Inconel 718 samples in this study are compared against their corresponding direct measurements from UTT in Figure 6.  
For seven of the eight samples, the discrepancy between the MSS and UTT measurements was \(\leq\)8%. Sample number 4 exhibited a higher difference in the modulus values between these two tests and is considered to be an outlier. The reasons for this discrepancy are not yet clear, but may reflect a higher level of heterogeneity or anisotropy in this AM sample. [PERSON] et al.