PSI - Issue 39

Szymon Derda et al. / Procedia Structural Integrity 39 (2022) 441–449 Author name / Structural Integrity Procedia 00 (2019) 000–000

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distinct influence of copper layer thickness and steel type on the fatigue life of the material. 5.3 Fatigue failure mechanism

The most common failure mechanism in the considered composites was the appearance of the distinct fatigue marks in the final stage of their life. First slip bands appeared in the tantalum layer and with time they were visible in the layer of copper. An example of severe fatigue marks were shown in Fig. 7.

Fig. 7. Distinct fatigue marks/streaks observed in Tantalum (left side) and Copper (right side) layers

6. Conclusions The data indicate that for Case 1 primary cracks form exclusively in the tantalum layer, whereas for Case 2 they appear mostly tantalum layer with two exceptions at the steel/copper interface. A wavy interface can be the region of high-stress concentration and the Case 2 composite is characterized by higher values of wave height and length. Moreover, the occurrence of primary cracks at the interface is rather occasional. This can be the result of varying values of wave height within Case 2. No relation between stress values and crack origin was observed. Regarding fatigue life, no distinct difference between both Cases was found. Further investigation on the impact of interface geometry on the fatigue life of explosively welded composites is recommended. Acknowledgments This study was supported by the National Centre for Research and Development, Poland [grant number Techmastrateg2/412341/8/NCBR/2019] . References [1] Y. Zhu, K. Ameyama, P.M. Anderson, I.J. Beyerlein, H. Gao, H.S. Kim, E. Lavernia, S. Mathaudhu, H. Mughrabi, R.O. Ritchie, N. Tsuji, X. Zhang, X. Wu, Heterostructured materials: superior properties from hetero-zone interaction, Mater. Res. Lett. 9 (2021) 1–31. https://doi.org/10.1080/21663831.2020.1796836. [2] Crossland Bernard, Explosive welding of metals and its application, Clarendon Press, Oxford, 1982. [3] F. Findik, Recent developments in explosive welding, Mater. Des. (2011). https://doi.org/10.1016/j.matdes.2010.10.017. [4] M. Prażmowski, D. Rozumek, H. Paul, Static and fatigue tests of bimetal Zr-steel made by explosive welding, Eng. Fail. Anal. 75 (2017) 71–81. https://doi.org/10.1016/j.engfailanal.2016.12.022. [5] A. Karolczuk, H. Paul, Z. Szulc, K. Kluger, M. Najwer, G. Kwiatkowski, Residual Stresses in Explosively Welded Plates Made of Titanium Grade 12 and Steel with Interlayer, J. Mater. Eng. Perform. 27 (2018) 4571–4581. https://doi.org/10.1007/s11665-018-3559-4. [6] A. Karolczuk, K. Kluger, S. Derda, M. Prazmowski, H. Paul, Influence of impact velocity on the residual stress, tensile strength, and structural properties of an explosively welded composite plate, Materials (Basel). 13 (2020). https://doi.org/10.3390/ma13122686.