PSI - Issue 61

Aptullah Karakaş et al. / Procedia Structural Integrity 61 (2024) 42 – 46 Aptullah Karakas / Structural Integrity Procedia 00 (2019) 000 – 000

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On the other hand, cold plastic deformation does not have an effect on coating hardness, because there is not any difference between specimens in different conditions. As for morphology of coatings, it could be observed that Kirkendall porosity increased more after diffusion annealing processes. It must be emphasized that Kirkendall porosity is observed on FF 4140 HDA-DA much more than 4140 HDA. This might be attributed to the increased lattice defects of the flow formed sample by cold plastic deformation such as dislocations. 4. Conclusion 1. Hot dip aluminizing process was successfully applied to an AISI 4140 steel in a molten Al7020 bath without any crack, porosity and delamination at the interface. The flow-formed specimens have a higher coating thickness, and it is seen that cold plastic deformation plays an important role on the coating thickness. 2. Kirkendall porosities were observed on the coatings of both specimens after the diffusion annealing. However, the flow formed samples have higher porosity, possibly increasing diffusional activity due to cold deformation of the flow forming. 3. Since cold plastic deformation has a remarkable effect on coating thickness, hot-dip aluminizing process parameters such as temperature and time can be adjusted. In this context, it suggests that a lower dipping temperature or shorter time for a flow formed specimen might produce the same thickness as non-flow formed specimen. 4. Surface condition is very important for hot dip processes because of wettability. Surface preparation with 180 grit sandpaper and cleaning with ethanol for 2 minutes in ultrasonic bath results in a successful wetting of molten aluminum during hot dip aluminizing. Al 7020 alloy has a sufficient fluidity at 750  C for a good components.

Acknowledgements The authors would like to thank Repkon Machine and Tool Industry and Trade Inc. which financially supported this study.

References

Bahadur, A., 1996, Aluminum Coatings for Steel, Materials and Manufacturing Processes, 11, 225- 232. Dey, P., Shrishty, S., Partha, S.B., and Manojit, G. 2023. A Review on Metallurgical Features of Hot-Dip Aluminized Steel. Engineering Research Express 5,1-38. Erdogan, C., Vural, H. Karakaş, A., Fenercioğlu, T.O., Yalçinkaya, T. 2023. Ductile Failure of Inconel 718 during Flow Formin g Process and Its Numerical Investigation. Engineering Failure Analysis 152. Karakaş, A., Fenercioğlu, T.O, and Yalçinkaya, T. 2021. The Influence of Flow Forming on the Precipitation Characteristics of Al2024 Alloys. Materials Letters 299. Springer, H., Kostka, A., Payton, E. J., Raabe, D., Kaysser-Pyzalla, A., and Eggeler, G. 2011. On the Formation and Growth of Intermetallic Phases during Interdiffusion between Low-Carbon Steel and Aluminum Alloys. Acta Materialia 59, 1586 – 1600. Verhoeven, J.D. “ Fundamentals of Physical Metallurgy ”. John Wiley & Sons, New York, 1989. Yazgan, E., Mutlu, M., Aydin, G., Karakaş, A., Fenercioglu, T.O., and Baydoğan , M. 2023. Mechanical and Microstructural Properties of AISI 4140 after Flow-Forming Process. Materials Research Proceedings 1029, 35. Yu, L., Jiang, W., An, X., Ni, S., Bo, G., Li, W., Song, M., Introducing both chemical and structural gradients in AISI 321 stainless steel via aluminizing and laser shock peening for superior properties. Surface and Coating Technology 472. Yürektürk, Y., and Baydoğan, M., 2018. Characterization of Ferritic Ductile Iron Subjected to Successive Aluminizing and Aust empering. Surface and Coatings Technology 347, 142 – 49.