PSI - Issue 53

S. Senol et al. / Procedia Structural Integrity 53 (2024) 12–28 Author name / Structural Integrity Procedia 00 (2019) 000–000

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utilized; 42 W, 500 mm/s, 0.07 mm, 30 ns, 100 kHz, as PW average laser power, scan speed, hatch spacing, pulse duration, and pulse repetition rate, respectively, and 300 W, 800 mm/s, and 0.07 mm, as CW laser power, scan speed, and hatch distance, respectively.

Fig. 2. Schematic describing the optimized dL-PBF process: (a) part obtained after completion of the L-PBF process, showing, from top to bottom, the focal plane (orange), the AM part covered with powder, the powder bed, and the build platform, (b) build platform is moved 3 mm upwards (DF3) to apply selective powder removal by sequentially scanning the defined areas (1 and 2) with the PW laser, (c) intermediate-step of powder removal: powder in area-1 is removed, then area-2 is scanned with PW, and longitudinal PW scan vector applied for selective powder removal is indicated with white arrows, (d) final step of powder removal: build platform is moved 1 extra mm upwards (DF4) and the full length of the 3PBF sample is scanned bi-directionally with the PW to ensure a powder free surface, (e) re-melting step: build platform is moved downwards (focus in the middle of the curved region) and part is scanned 2 times with 45° tilt scan strategy using the CW laser. The respective final (top) surface conditions, namely, as-built (AB), dL-PBF processed (R), wire electric-discharge machined (EDM), and milled (M), are displayed in Fig. 3.

Fig. 3. Top view (XY) of the 3PBF samples with different surface conditions; (a) as-built (AB), (b) dL-PBF processed (R), (c) wire electric discharge machined (EDM), and (d) milled (M).