## 3 Results
### MSS Measurements
[7] reviewed literature on a wide range of metal AM processes and focused on how the heterogeneity and anisotropy in an AM microstructure can lead to variations in mechanical properties. Since the material volume probed in the MSS is significantly smaller compared to UTT, heterogeneity in the sample is likely to result in some of the differences noted in the modulus values in Figure 6. [PERSON] et al. [34] studied the issue of heterogeneity in spherical indentation load-displacement responses and how to develop a confidence domain using the variation between experimental load-displacement  
Figure 5: An overlay of data collected from five MSS tests conducted on Sample number 8 on the corresponding UTT stress-strain curve. curves. They focused on the error distribution between FE simulations and experimental load-displacement curves and on the average representative strain from multiple experimental tests to determine a confidence domain. It should also be noted that the Equation (3) is based on an isotropic material response. Consequently, any anisotropy in the material response can also contribute to the observed differences in Figure 6.  
The 0.2% offset UTT yield strength can be estimated from the 0.2% offset MSS yield strength by dividing it by a scaling factor of 2.0 as [PERSON] and [PERSON] [17] demonstrated and validated in their FE simulation studies. Figure 7 shows a comparison of the average and standard deviation of the tensile yield strength values extracted from MSS measurements for all samples tested in this work against the yield strength values measured directly from the UTT. Figure 6: Estimated values of Young’s modulus obtained from MSS tests presented as averages and standard deviations, along with the corresponding UTT measurements. The table summarizes the percent variation between the average of the MSS moduli and the UTT modulus for each sample. \[\varepsilon_{PMSS}=\varepsilon_{TMSS}-\varepsilon_{eMSS} \tag{11}\]0 Estimates of yield strengths from MSS tests presented as averages and standard deviations, along with the corresponding UTT measurements. The table summarizes the percent variation between the average MSS estimated yield strength and the UTT measured yield strength. It is seen that the MSS estimated values are in particularly good agreement with the values measured directly from UTT. In fact, the largest discrepancy in the MSS estimated yield strengths among the eight samples was 10%, and seven samples exhibited an error \(\leq\)6%. These comparisons demonstrate the high reliability of MSS protocols in determining the yield properties of an AM material. The highest difference of 10% was observed in Sample number 4. Given the role of elastic modulus in the estimation of the contact radius, indentation stress, and indentation strain values, it is not surprising that the sample that produced an erroneous estimate of the modulus also produced the highest error in the estimate of yield strength. It was also observed that the scaling factor of 2.0 resulted in a consistent underprediction of yield strength. [PERSON] et al. [19] observed a similar trend in their experimental results on aluminum alloys, where they concluded that a factor of 1.89 resulted in higher accuracy estimates. It is reiterated that the scaling factor of 2.0, used in the present study, was determined based on FE simulations that employed isotropic plasticity material constitutive laws. Therefore, this difference could indicate some degree of anisotropy in the mechanical response of the AM sample. As already described earlier, the heterogeneity of the microstructure in the AM sample at the scale of the indentation zone could also contribute to the observed differences.