## 3 Results
Figure 9 summarizes the overall behavior, in terms of force-displacement curves, of barrel-finished and heat-treated samples. For the BF (Figure 9a), only one sample was tested for each combination of building direction and finishing intensity, while for the thermally treated specimens, the median value of three repetitions was reported in Figure 9b. Figure 10 shows the corresponding engineering stress-strain curves for barrel-finished and heat-treated specimens, respectively, calculated using the actual specimen dimensions measured before the tests. The barrel-finished samples exhibited a maximum scatter below 15% in terms of yielding stress, while the thermal-treated specimens showed an improved behavior in terms of repeatability, with the only exception being the samples treated at 482 \({}^{\circ}\)C (TT 482), with a significantly higher yielding value. Their yielding stress, higher than 1050 MPa, resulted in being comparable to that of the barrel-finished samples, which did not receive any thermal treatment. Conversely, both the elongation at break and ultimate tensile strength demonstrated a higher scatter due to the influence by the postprocesses. Their values are reported in Figures 11a and 12a. In this case, for the heat-treated specimens, the mean values of the three repetitions are used. In Figures 11b and 12b, the mean values of ultimate tensile strength, yield stress and elongation at break are summed up for each level of surface finish and each temperature. Finally, the percentage of area reduction at fracture of the barrel-finished specimens, evaluated close to the most critical section, is illustrated in Figure 13.  
samples cured at 482 \({}^{\circ}\)C revealed a yield stress comparable to that typical of untreated samples (around 1050 MPa). All the postprocess treatments had a significant influence on the elongation at break. Both the barrel-finished samples' subsets exhibited an increased fracture elongation of about 25%, while the heat-treatments enhanced the elongation, with respect to their intensity, up to more than 30%. Eventually, the area reduction also showed an increasing trend with the increase of BF velocity. The influence on the ductility of surface finish condition can be interpreted as the effect of high surface roughness, typical of as-built specimens, which might act as a crack initiator. Such roughness, typically in the range of Ra = 5-15 \(\upmu\)m [23], can be regarded as a series of superficial defects, causing a stress intensification in some spots on the surface of the sample, which in turn produce a premature fracture. The interpretation is that, when the first fracture appears, the stress distribution is not yet the typical one of tensile specimens, in which the critical point, where the deformation should be localized, is known to be the one in the middle of the cross-section. Thus, at fracture onset, the expected critical point inside is not more critical than other points on the surface, where conversely the fracture can be triggered by superficial defects causing a local stress intensification. To support these hypotheses, a numerical simulation of a tensile test was performed to assess the plastic strain at the fracture onset. The simulation was carried out, using the commercial finite-element analysis code ANSYS. The material was regarded as isotropic and described with a nonlinear stress-strain law, based on [PERSON]'s formulation. The specimen was discretized, using solid elements with quadratic formulation with an average element length of 0.1 mm. All the possible symmetries were exploited in the modeling, in order to reduce the number of elements required. Surface roughness and residual stresses were neglected. The results, which are reported in Figure 14, show how the total equivalent plastic strain exhibits a nearly homogeneous distribution along the cross-section, showing only a marginal concentration in the inner area.