PSI - Issue 83

Niccolò Vilotta et al. / Procedia Structural Integrity 83 (2026) 246–255

251

(a)

(b) Figure 5: Hardness distribution across weld section (a), zoning throughout the material (b).

Table 1 reports the average hardness and strength values obtained for each of the three regions. The base material is characterized by the highest hardness and strength values, the heat-affected zone exhibits intermediate values, and the weld metal shows the lowest ones. Accordingly, in the welded DMLS AISI 316L investigated in the present work, the local mechanical response decreases progressively from the base material to the weld metal, with the heat-affected zone lying in between. A similar hardness profile for laser-welded additively manufactured AISI 316L, with the fusion zone showing lower hardness than the base material and the heat-affected zone displaying intermediate values, was reported by Mokhtari et al. [17]. This trend differs from what is often reported for conventional AISI 316L welds, where the weld region can exhibit comparable or higher hardness and strength than the base material [12,15]. Table 1. Average HV, HB, yield strength, and ultimate tensile strength values for welded DMLS-manufactured AISI 316L stainless steel. Region HV [-] HB [-] σ y [MPa] σ UTS [MPa] BM 200 190 448 669 HAZ 185 176 407 619 WM 178 169 386 593 The following figure shows the true stress–true strain curves obtained using the Kamaya model (Figure 6(a)) and the Lopez and Fatemi method (Figure 6 (b)). The comparison reported in Table 2 shows that, for the non-welded specimen, the strengths estimated from hardness measurements are in satisfactory agreement with those obtained directly from tensile testing. In particular, the percentage difference is 3.3% for the yield strength and 5.7% for the ultimate tensile strength. Such deviations are limited and indicate that, in the case of the base material, the hardness-based constitutive reconstruction can reproduce the overall resistance level with acceptable accuracy.