PSI - Issue 77

M. Turhan et al. / Procedia Structural Integrity 77 (2026) 543–549 M.Turhan et al. / Structural Integrity Procedia 00 (2026) 000 – 000

547

5

Alloy HX 2 Vert HX 2 Hor HX 2 Alloy HX 3 Vert HX 3 Alloy HX 4 Vert HX 4 Hor HX 4 Alloy HX 5 Vert HX 5 Hor HX 5

386 407 442 360 381 299 427 460 280 392 424

720 749 836 688 706 733 780 877 667 732 796

25 35 26 37 37 43 32 18 30 34 15

23 36 28 32 35 49 33 17 23 34 18

209 200 183 199 199 184 197 181 390 224 185

Air Air Air Air Air

900 900 900 900 900 900 900 900 900 900 900

1000 1000 1000 5000 5000 1000 1000 1000 5000 5000 5000

Nitrogen Nitrogen Nitrogen Nitrogen Nitrogen Nitrogen

The ductility of tensile test samples was decreased while they were exposed to air and nitrogen at 900 ° C at 1000 hours and 5000 hours of durations. The horizontally printed samples were experienced the lowest reduction of area values, but the conventional HX had the highest change in embrittlement especially at 5000 hours duration during nitrogen exposure. This may have caused due to horizontal samples having rougher surfaces because of large amount of support structures were placed to hold horizontal samples during printing process. The microstructural observations showed that conventional HX had strong precipitation. On the other hand, vertically printed samples had gradual decrease in ductility unlike other samples. The horizontal samples had almost in all cases the highest ultimate tensile strength values [17]. 3.2. Fatigue tests High-cycle fatigue tests were conducted on a RUML Testronic machine with a 100 kN force capacity. The tests followed the ASTM E486-23a standard at room temperature, using stress ratio of R=0. The failure criterion was defined as either the frequency dropped to 10 Hz or getting to 10 7 cycles.

High Cyle Fatigue

100 150 200 250 300

conventional HX vertical EOS HX

0 50

Stress Amplitude(MPa)

1.00E+04

1.00E+05

1.00E+06

1.00E+07

1.00E+08

Cycles

Figure 3 S-N curves of conventional Alloy HX and vertically 3D printed EOS HX materials

Based on the S-N (Wöhler) curve data, the conventional HX samples have better high-cycle fatigue resistance than the vertically printed EOS HX samples. The Figure 3 shows that the fatigue strength of the vertically printed EOS HX