PSI - Issue 77

V. Kroužecký et al. / Procedia Structural Integrity 77 (2026) 161 – 169 Vít Kroužecký / Structural Integrity Procedia 00 (2026) 000 – 000

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Table 3 DOE - process parameters and calculated VED for downskin samples

Sample P [W] Hatch distance [mm] VED [J/mm3] Sample P [W] Hatch distance [mm] VED [J/mm3]

1 2 3 4 5 6

100 100 100 100 150 150

0,055

≈47,8 ≈37,6 ≈32,9 ≈29,2 ≈71,7 ≈56,4

7 8 9

150 150 200 200 200 250

0,08 0,09 0,07 0,08 0,09 0,09

≈49,4 ≈43,8 ≈75,2 ≈65,8 ≈58,4 ≈74,1

0,07 0,08 0,09

10 11 12

0,055

0,07

The surface roughness test specimens were distributed across the build platform along the direction of the protective gas flow. However, the laser scanning strategy was oriented against the gas flow. This arrangement was chosen to minimize the risk of spatter particles, generated during melting, interfering with the laser beam and causing a loss of focus. To ensure repeatability and account for potential spatial variability across the platform, each specimen was fabricated three times at different positions on the build plate. he layout of the specimens on the platform is illustrated in Figure 2 Layout of surface roughness test specimens on the build platform (left) Surface roughness specimen (right)

Recoate

(Ar)

Flow

Figure 2 Layout of surface roughness test specimens on the build platform (left) Surface roughness specimen (right)

Figure 3 Effect of volumetric energy density on down surface quality at different inclination angles illustrates the relationship between surface roughness (Sz) and volumetric energy density (VED) for down surfaces manufactured at inclination angles of 35°, 30°, and 25°. A general trend can be observed, whereby increasing VED results in reduced surface roughness, indicating an improvement in down surface quality with higher energy input. For the 35° inclination, all twelve parameter sets were evaluated, whereas for the more challenging inclination angles of 30° and 25°, only the five best-performing parameter sets (identified from the 35° experiments) were tested. The results