PSI - Issue 52

Tomáš Vražina et al. / Procedia Structural Integrity 52 (2024) 43 – 51 Tomáš Vražina et. al/ Structural Integrity Procedia 00 ( 2022) 000 – 000

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8

Table 4 Estimation of Paris-Erdogan law coefficients from eq. (1). LPBF

HR =0.5 2.96 × 10 -10

=0.5 3.41 × 10 -10

=0.7 0.19 × 10 -10

=0.7 3.4 × 10 -10

Strain amplitude (%)

(-)

(-)

2.52

2.57

2.43

2.19

4. Conclusion An experimental study of the room temperature LCF behavior of alloy 699 XA manufactured by hot rolling and laser powder bed fusion led to the following conclusions: 1) The grain size of both materials is comparable. The microstructure of both material batches shows no preferential orientation. 2) The softening/hardening behavior of LPBF and HR 699 XA material is strain dependent. The character of the stress response of both material batches is the same. Initial cyclic hardening followed by cyclic softening is typical for ε a ≥ 0.35% whereas continuous cyclic hardening till fracture occurred for lower strain amplitudes. 3) Despite the presence of few AM defects (density of 99.87%), LPBF material shows slightly improved fatigue life in both Basquin and Coffin-Manson representation. 4) In both cases, fatigue crack initiation took place at the surface of specimens. In the case of LPBF material, unmelted particles and porosity were found in the close vicinity of fatigue crack initiation sites. 5) Crack growth rate of LPBF material starts to incline much faster to stage III of the da/dN- ∆K curve than in the case of HR material, even the slope characterized by exponent m is slightly higher in the case of LPBF material. The origin of this behavior can be assigned to AM defects. Acknowledgements Authors would like to acknowledge the financial support from European Union ’s Horizon 2020 research and Innovation programme under grant agreement No 958192. References Sanchez, S . , P . Smith, Z . Xu, G . Gaspard, C . J. Hyde, W . W. Wits, I . A. Ashcroft, H . Chen, and A . T. Clare. 2021. “Powder Bed Fusion of Nickel Based Superalloys: A Review.” International Journal of Machine Tools & Manufacture 165 (June): 103729. White, E . , C . Schlereth, M . Lepple, H . Hattendorf, B . Nowak, and M . C. Galetz. 2023. “Influence of Surface Treatment on the Metal Dusting Behavior of Alloy 699 XA.” Materials and Corrosion 74 (2): 190 – 96. Schlereth, C . , C . Oskay, H . Hattendorf, B . Nowak, and M . C. Galetz. 2022. “Influence of Al and Fe Additions on Metal Dusting of NiCr Alloys.” Materials and Corrosion 73 (9): 1346 – 58 Babinský, T., I. Kuběna, I. Šulák, T. Kruml, J. Tobiáš, and J. Polák. 2021. “Surface Relief Evolution and Fatigue Crack Initiation in René 41 Superalloy Cycled at Room Temperature.” Materials Science and Engineering: A 819 (July): 141520. Polák, J., V. Mazánová, M. Heczko, R. Petráš, I. Kuběna, L. Casalena, and J. Man. 2017. “The Role of Extrusions and Intrusions in Fatigue Crack Initiation.” Engineering Fracture Mechanics 185 (November): 46 – 60. Zheng, J . , M . W. Fu, and F. Zeng. 2022. “Design and Development of Multi - Scaled Metallic Parts and Structures.” In Encyclopedia of Materials: Metals and Alloys , edited by Francisca G. Caballero, 3 – 18. Oxford: Elsevier. Chlupová, A . , I . Šulák, I . Kuběna, T . Kruml, J - P . Roth, K . Jahns. 2023. “Comparison of Microstructure and Properties of Nickel - Copper Alloy Prepared by Casting and Laser Powder Bed Fusion Process.” Materials Science Forum 1082 (March): 171 – 76. Zhu, J . , H . Zhou, C . Wang, L . Zhou, S . Yuan, and W . Zhang. 2021. “A Review of Topology Optimization for Additive Manufacturing: Status and Challenges.” Chinese Journal of Aeronautics 34 (1): 91 – 110