PSI - Issue 79

Saveria Spiller et al. / Procedia Structural Integrity 79 (2026) 176–181

178

Table 1: chemical composition of the IN625 powder that was used in the L-PBF process.

wt% C

Al

Si

Ti

Mn

Cr

Fe

Ni

Nb

Mo

IN625 powder

0.1

<0.4

<0.5

<0.4

<0.4

20.00-23.00

<5.00

Bal.

3.15-4.15 8.00-10.00

Fig. 1: schematic of the printing layout of the L-PBF plate that was welded.

Table 2: laser welding parameters adopted to weld the BoP.

Mode

P avg [W]

v [mm/s]

R

PW

1920

25

0.6

3. Results and Discussion 3.1. Investigation on the L-PBF parent material

The quality obtained via the AM process was assessed through the microscopical investigation on the parent material (PM) reported in Fig. 2. The EBSD technique was used to obtain an Inverse Pole Figure map to investigate the microstructure of the PM considering a region sufficiently far from the fusion zone (FZ) and the possible alteration that the welding process induces, as depicted in the schematic in Fig. 2a. The map, Fig. 2b shows a very fine microstructure, with elongated grains along the building direction (BD). SEM pictures, taken on the etched cross-section, revealed the so-called ‘melting pools’ that represent the laser tracks (Fig. 2c). Overall, the material presents a very limited number of defects, with one example reported in Fig. 2d: the picture shows unmelted powder trapped in a wide cavity (Tian et al., 2020). This is a typical defect of L-PBF components.

Fig. 2: investigation on the parent material. a) schematic of the observed region; b) EBSD analysis map of the observed region; c) characteristic melting pool traces; d) a typical L-PBF defect, trapped unmelted powder