## 3 Results and Discussions
### Effect of Aging Heat Treatment  
Figure 6 shows the deformations of the cantilever specimens while cutting the supporter legs, after the aging heat treatments. The heat treatments of the cantilevers were carried out for the specimens with the artificial supporter (i.e., shown in Figure 1b), thus both the cantilevers and the supporters were made by the LPBF-processed maraging steel in this case. Figure 6a shows the deformations caused by cutting each supporter leg of the cantilevers, heat treated with direct aging at 500 \({}^{\circ}\)C for 6 h, without the solution heat treatment. Unlike the case of the as-built state in which the thin cantilevers showed significant downward distortions, the heat-treated cantilevers showed upward distortions regardless of the thickness of the cantilever, as shown in Figure 6a. It can be seen that the upward distortion tends to increase with increasing the thickness of the cantilever. Figure 5: Comparisons of deformations caused by cutting supporter legs, between FEM simulations and experiments. (**a**) Deformation changes caused by cutting each leg and (**b**) Final deformation after cutting all supporter legs. Figure 6b shows the final deformations after cutting all the supporter legs for the managing steel cantilevers in three different heat treatment states, as-built, direct aging without solution heat treatment, and aging followed by the solution heat treatment. The aging heat-treated cantilevers showed negligible deformations when the thickness of the cantilevers were 0.5 mm. The deformations increased slightly and continuously with increasing cantilever thickness. The final deformations for the cantilevers with various thicknesses were nearly identical between the aging heat-treated specimens with and without solution heat treatment at 850 \({}^{\circ}\)C for 2 h, indicating that the solution heat treatment does not have any influence on the residual stress state of the cantilever after the aging heat treatment. This means that the aging heat treatment at 500 \({}^{\circ}\)C for 6 h is able to almost completely relieve the residual stress that occurred during the LPBF process. This result indicates that solution heat treatment is not necessary for the purpose of residual stress relief for the managing 18 Ni-300 steel components produced by the LPBF. Due to the limited number of samples used for the investigation, only one cantilever sample for each condition was subjected to the test. Thus, possible deviations associated with experimental error have not been accessed. However, when considering the nearly identical final deformation behaviors between the cantilevers in two different aging heat treatment states of direct aging and aging followed by the solutioning, the deformations that occurred in the aging heat-treated cantilever specimens were probably not a result of experimental error. These near-identical deformations obtained from differently heat-treated samples also reflect the fairly good reproducibility of the cantilever method used for this study. One possible cause of the upward deformations in the heat-treated cantilevers is the small amount of residual stress that cannot be completely removed by the heat treatment. Another possible cause of the upward deformation could be the precipitations and lattice distortions occurring in the aging heat treatment. As shown in the authors' previous work [9], the managing steel incurs fine intermetallic compounds as precipitates during the aging which can cause a volumetric change in the managing steel by the lattice distortion near the precipitate or by the lattice parameter change in the matrix due to the change in solute concentration. Nevertheless, the number of upward distortions after the heat treatment was trivial when comparing them with the downward distortions observed in the thin cantilevers in the as-built state.