PSI - Issue 68

Antti Järvenpää et al. / Procedia Structural Integrity 68 (2025) 619–625 Antti Järvenpääa et al. / Structural Integrity Procedia 00 (2025) 000–000

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2.2. Manufacturing of the test samples The specimens (Fig. 2) were fabricated using laser powder bed fusion (LPBF) AM technology (SLM 280 HL). The material used was powdered Ti–6Al–4V ELI (Grade 23) Titanium from SLM Solutions (Lübeck, Germany), with a spherical particle size of 30 μm and a density of 4.43 g/cm3. For the LPBF processing, a laser power of 500 W was employed for contours and 300 W for hatches, utilizing a “Stripes” fill pattern type for external regions and a “Chessboard” pattern for the volume core. Layer thickness of 30 µm was used, and hatching was set with a tolerance of 100 µm and a distance of 120 µm. The theoretical build-up rate was 14.2 cm 3 /h. After LPBF manufacturing, the specimens were vacuum heat treated at 800 ℃ for 2 h.

Fig. 2. LPBF manufactured Ti6Al4V tension (upper samples) and compression (bottom samples) test designs.

2.3. Mechanical testing Axial static tests were performed with a Universal System Machine Zwick 100 KN. The compression strain rate used was 10 −2 s −1 (ISO 13314) and a constant tension displacement rate of 10 mm/min. The compression tests were carried out with two parallel aligned plates located at the top and bottom sides of the specimens. Customized holders were used to align and secure the tensile specimens. Two methods were used to calculate the stresses under axial testing. For the first method (A), the nominal diameter of the specimens was used to calculate the cross-sectional area as a bulk material. For the second method (B), an average of 30 cross-sectional area measurements along the open-cell porous structures was used (Fig. 3).

Fig. 3. Principle of calculating the cross-sectional area.