PSI - Issue 77

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

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

(the blue line and dots) drops off much more steeply than the conventional HX (the red line and dots) samples. This indicates that the conventional HX samples have better fatigue life compared to vertically printed EOS HX samples. In fact, the fatigue strength of the 3D-printed material decreases 59.3% faster for the same number of cycles compared to the conventional HX [17]. 3.3. Creep tests Creep tests were done on conventional HX, vertically printed EOS HX, and horizontally printed EOS HX samples at 800°C, 900°C, and 1000°C. Outputs of the tests were evaluated according to Larson-Miller parameter as seen in Figure 4. The outputs of the tests show that fracture stresses at high temperature for manufactured by the L-PBF technology in the vertical direction have very similar results in terms of high strength properties with conventional HX samples. On the other hand, horizontally printed EOS HX test samples have noticeable decrease in the high temperature strength, particularly at higher test parameters. However, vertically printed EOS HX, and horizontally printed EOS HX samples have remarkably lower ductility values compared to conventional HX samples [17], [19].

Creep-rupture properties

1000

conventional HX vertical EOS HX horizontal EOS HX

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10

Fracture stress [MPa]

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22000

24000

26000

28000

30000

32000

Larson-Miller Parameter, T(20 +log t), T in °K, t in hours

Figure 4 Creep-rupture properties of conventional HX, vertically printed EOS HX, and horizontally printed EOS HX samples

Besides mechanical tests, some test coupons were subjected to high temperature oxidation tests in supercritical water environment. The test coupons were held at 650°C and 300 bars with 1000 hours of exposure time. Material losses were observed. The absolute values of changes were very low that they were not necessarily to be considered [17]. 4. Conclusions The printability and mechanical properties of Hastelloy X (HX) powder by Laser Powder Bed Fusion (L-PBF) technology was investigated in this work. The following conclusions can be drawn from this investigation: • The results of tensile show that all test samples have experienced embrittlement when they were exposed to air and nitrogen at high temperatures for long periods. • The fatigue life of conventional HX samples were better than vertically printed EOS HX samples which had more than 50 percent decrease in fatigue life.